draft-ietf-taps-transports-07.txt   draft-ietf-taps-transports-08.txt 
Network Working Group G. Fairhurst, Ed. Network Working Group G. Fairhurst, Ed.
Internet-Draft University of Aberdeen Internet-Draft University of Aberdeen
Intended status: Informational B. Trammell, Ed. Intended status: Informational B. Trammell, Ed.
Expires: April 9, 2016 M. Kuehlewind, Ed. Expires: June 10, 2016 M. Kuehlewind, Ed.
ETH Zurich ETH Zurich
October 07, 2015 December 08, 2015
Services provided by IETF transport protocols and congestion control Services provided by IETF transport protocols and congestion control
mechanisms mechanisms
draft-ietf-taps-transports-07 draft-ietf-taps-transports-08
Abstract Abstract
This document describes services provided by existing IETF protocols This document describes transport services provided by existing IETF
and congestion control mechanisms. It is designed to help protocols. It is designed to help application and network stack
application and network stack programmers and to inform the work of programmers and to inform the work of the IETF TAPS Working Group.
the IETF TAPS Working Group.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 9, 2016. This Internet-Draft will expire on June 10, 2016.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Existing Transport Protocols . . . . . . . . . . . . . . . . 5 3. Transport Service Features . . . . . . . . . . . . . . . . . 4
3.1. Transport Control Protocol (TCP) . . . . . . . . . . . . 5 3.1. Congestion Control . . . . . . . . . . . . . . . . . . . 5
3.1.1. Protocol Description . . . . . . . . . . . . . . . . 5 4. Existing Transport Protocols . . . . . . . . . . . . . . . . 6
3.1.2. Interface description . . . . . . . . . . . . . . . . 6 4.1. Transport Control Protocol (TCP) . . . . . . . . . . . . 6
3.1.3. Transport Features . . . . . . . . . . . . . . . . . 7 4.1.1. Protocol Description . . . . . . . . . . . . . . . . 6
3.2. Multipath TCP (MPTCP) . . . . . . . . . . . . . . . . . . 8 4.1.2. Interface description . . . . . . . . . . . . . . . . 8
3.2.1. Protocol Description . . . . . . . . . . . . . . . . 8 4.1.3. Transport Features . . . . . . . . . . . . . . . . . 8
3.2.2. Interface Description . . . . . . . . . . . . . . . . 8 4.2. Multipath TCP (MPTCP) . . . . . . . . . . . . . . . . . . 9
3.2.3. Transport features . . . . . . . . . . . . . . . . . 8 4.2.1. Protocol Description . . . . . . . . . . . . . . . . 9
3.3. Stream Control Transmission Protocol (SCTP) . . . . . . . 9 4.2.2. Interface Description . . . . . . . . . . . . . . . . 9
3.3.1. Protocol Description . . . . . . . . . . . . . . . . 9 4.2.3. Transport features . . . . . . . . . . . . . . . . . 10
3.3.2. Interface Description . . . . . . . . . . . . . . . . 12 4.3. Stream Control Transmission Protocol (SCTP) . . . . . . . 10
3.3.3. Transport Features . . . . . . . . . . . . . . . . . 14 4.3.1. Protocol Description . . . . . . . . . . . . . . . . 11
3.4. User Datagram Protocol (UDP) . . . . . . . . . . . . . . 15 4.3.2. Interface Description . . . . . . . . . . . . . . . . 13
3.4.1. Protocol Description . . . . . . . . . . . . . . . . 15 4.3.3. Transport Features . . . . . . . . . . . . . . . . . 15
3.4.2. Interface Description . . . . . . . . . . . . . . . . 16 4.4. User Datagram Protocol (UDP) . . . . . . . . . . . . . . 16
3.4.3. Transport Features . . . . . . . . . . . . . . . . . 16 4.4.1. Protocol Description . . . . . . . . . . . . . . . . 16
3.5. Lightweight User Datagram Protocol (UDP-Lite) . . . . . . 17 4.4.2. Interface Description . . . . . . . . . . . . . . . . 17
3.5.1. Protocol Description . . . . . . . . . . . . . . . . 17 4.4.3. Transport Features . . . . . . . . . . . . . . . . . 18
3.5.2. Interface Description . . . . . . . . . . . . . . . . 18 4.5. Lightweight User Datagram Protocol (UDP-Lite) . . . . . . 18
3.5.3. Transport Features . . . . . . . . . . . . . . . . . 18 4.5.1. Protocol Description . . . . . . . . . . . . . . . . 18
3.6. Datagram Congestion Control Protocol (DCCP) . . . . . . . 19 4.5.2. Interface Description . . . . . . . . . . . . . . . . 19
3.6.1. Protocol Description . . . . . . . . . . . . . . . . 19 4.5.3. Transport Features . . . . . . . . . . . . . . . . . 19
3.6.2. Interface Description . . . . . . . . . . . . . . . . 20 4.6. Datagram Congestion Control Protocol (DCCP) . . . . . . . 20
3.6.3. Transport Features . . . . . . . . . . . . . . . . . 21 4.6.1. Protocol Description . . . . . . . . . . . . . . . . 20
3.7. Lightweight User Datagram Protocol (UDP-Lite) . . . . . . 21 4.6.2. Interface Description . . . . . . . . . . . . . . . . 21
3.7.1. Protocol Description . . . . . . . . . . . . . . . . 21 4.6.3. Transport Features . . . . . . . . . . . . . . . . . 22
3.7.2. Interface Description . . . . . . . . . . . . . . . . 22 4.7. Internet Control Message Protocol (ICMP) . . . . . . . . 22
3.7.3. Transport Features . . . . . . . . . . . . . . . . . 22 4.7.1. Protocol Description . . . . . . . . . . . . . . . . 23
3.8. Internet Control Message Protocol (ICMP) . . . . . . . . 23 4.7.2. Interface Description . . . . . . . . . . . . . . . . 24
3.8.1. Protocol Description . . . . . . . . . . . . . . . . 23 4.7.3. Transport Features . . . . . . . . . . . . . . . . . 24
3.8.2. Interface Description . . . . . . . . . . . . . . . . 24 4.8. Realtime Transport Protocol (RTP) . . . . . . . . . . . . 24
3.8.3. Transport Features . . . . . . . . . . . . . . . . . 24 4.8.1. Protocol Description . . . . . . . . . . . . . . . . 24
3.9. Realtime Transport Protocol (RTP) . . . . . . . . . . . . 25 4.8.2. Interface Description . . . . . . . . . . . . . . . . 25
3.9.1. Protocol Description . . . . . . . . . . . . . . . . 25 4.8.3. Transport Features . . . . . . . . . . . . . . . . . 26
3.9.2. Interface Description . . . . . . . . . . . . . . . . 26 4.9. File Delivery over Unidirectional Transport/Asynchronous
3.9.3. Transport Features . . . . . . . . . . . . . . . . . 26
3.10. File Delivery over Unidirectional Transport/Asynchronous
Layered Coding Reliable Multicast (FLUTE/ALC) . . . . . . 26 Layered Coding Reliable Multicast (FLUTE/ALC) . . . . . . 26
3.10.1. Protocol Description . . . . . . . . . . . . . . . . 27 4.9.1. Protocol Description . . . . . . . . . . . . . . . . 27
3.10.2. Interface Description . . . . . . . . . . . . . . . 29 4.9.2. Interface Description . . . . . . . . . . . . . . . . 29
3.10.3. Transport Features . . . . . . . . . . . . . . . . . 29 4.9.3. Transport Features . . . . . . . . . . . . . . . . . 29
3.11. NACK-Oriented Reliable Multicast (NORM) . . . . . . . . . 30 4.10. NACK-Oriented Reliable Multicast (NORM) . . . . . . . . . 30
3.11.1. Protocol Description . . . . . . . . . . . . . . . . 30 4.10.1. Protocol Description . . . . . . . . . . . . . . . . 30
3.11.2. Interface Description . . . . . . . . . . . . . . . 31 4.10.2. Interface Description . . . . . . . . . . . . . . . 31
3.11.3. Transport Features . . . . . . . . . . . . . . . . . 32 4.10.3. Transport Features . . . . . . . . . . . . . . . . . 31
3.12. Transport Layer Security (TLS) and Datagram TLS (DTLS) as 4.11. Transport Layer Security (TLS) and Datagram TLS (DTLS) as
a pseudotransport . . . . . . . . . . . . . . . . . . . . 32 a pseudotransport . . . . . . . . . . . . . . . . . . . . 32
3.12.1. Protocol Description . . . . . . . . . . . . . . . . 33 4.11.1. Protocol Description . . . . . . . . . . . . . . . . 32
3.12.2. Interface Description . . . . . . . . . . . . . . . 34 4.11.2. Interface Description . . . . . . . . . . . . . . . 33
3.12.3. Transport Features . . . . . . . . . . . . . . . . . 34 4.11.3. Transport Features . . . . . . . . . . . . . . . . . 34
3.13. Hypertext Transport Protocol (HTTP) over TCP as a 4.12. Hypertext Transport Protocol (HTTP) over TCP as a
pseudotransport . . . . . . . . . . . . . . . . . . . . . 35 pseudotransport . . . . . . . . . . . . . . . . . . . . . 35
3.13.1. Protocol Description . . . . . . . . . . . . . . . . 36 4.12.1. Protocol Description . . . . . . . . . . . . . . . . 35
3.13.2. Interface Description . . . . . . . . . . . . . . . 37 4.12.2. Interface Description . . . . . . . . . . . . . . . 36
3.13.3. Transport features . . . . . . . . . . . . . . . . . 37 4.12.3. Transport features . . . . . . . . . . . . . . . . . 37
4. Transport Service Features . . . . . . . . . . . . . . . . . 38 5. Transport Service Features . . . . . . . . . . . . . . . . . 37
4.1. Complete Protocol Feature Matrix . . . . . . . . . . . . 40 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 7. Security Considerations . . . . . . . . . . . . . . . . . . . 41
6. Security Considerations . . . . . . . . . . . . . . . . . . . 42 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 41
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 42 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 42
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 43 10. Informative References . . . . . . . . . . . . . . . . . . . 42
9. Informative References . . . . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52
1. Introduction 1. Introduction
Most Internet applications make use of the Transport Services Internet applications make use of the Services provided by a
provided by TCP (a reliable, in-order stream protocol) or UDP (an Transport protocol, such as TCP (a reliable, in-order stream
unreliable datagram protocol). We use the term "Transport Service" protocol) or UDP (an unreliable datagram protocol). We use the term
to mean the end-to-end service provided to an application by the "Transport Service" to mean the end-to-end service provided to an
transport layer. That service can only be provided correctly if application by the transport layer. That service can only be
information about the intended usage is supplied from the provided correctly if information about the intended usage is
application. The application may determine this information at supplied from the application. The application may determine this
design time, compile time, or run time, and may include guidance on information at design time, compile time, or run time, and may
whether a feature is required, a preference by the application, or include guidance on whether a feature is required, a preference by
something in between. Examples of features of Transport Services are the application, or something in between. Examples of features of
reliable delivery, ordered delivery, content privacy to in-path Transport Services are reliable delivery, ordered delivery, content
devices, and integrity protection. privacy to in-path devices, and integrity protection.
The IETF has defined a wide variety of transport protocols beyond TCP The IETF has defined a wide variety of transport protocols beyond TCP
and UDP, including SCTP, DCCP, MP-TCP, and UDP-Lite. Transport and UDP, including SCTP, DCCP, MP-TCP, and UDP-Lite. Transport
services may be provided directly by these transport protocols, or services may be provided directly by these transport protocols, or
layered on top of them using protocols such as WebSockets (which runs layered on top of them using protocols such as WebSockets (which runs
over TCP), RTP (over TCP or UDP) or WebRTC data channels (which run over TCP), RTP (over TCP or UDP) or WebRTC data channels (which run
over SCTP over DTLS over UDP or TCP). Services built on top of UDP over SCTP over DTLS over UDP or TCP). Services built on top of UDP
or UDP-Lite typically also need to specify additional mechanisms, or UDP-Lite typically also need to specify additional mechanisms,
including a congestion control mechanism (such as NewReno, TFRC or including a congestion control mechanism (such as NewReno, TFRC or
LEDBAT). This extends the set of available Transport Services beyond LEDBAT). This extends the set of available Transport Services beyond
those provided to applications by TCP and UDP. those provided to applications by TCP and UDP.
[GF: Ledbat is a mechanism, not protocol - hence use the work
"support" in para below.]
Transport protocols can also be differentiated by the features of the
services they provide: for instance, SCTP offers a message-based
service providing full or partial reliability and allowing to
minimize the head of line blocking due to the support of unordered
and unordered message delivery within multiple streams, UDP-Lite and
DCCP provide partial integrity protection, and LEDBAT can support
low-priority "scavenger" communication.
2. Terminology 2. Terminology
The following terms are defined throughout this document, and in The following terms are defined throughout this document, and in
subsequent documents produced by TAPS describing the composition and subsequent documents produced by TAPS describing the composition and
decomposition of transport services. decomposition of transport services.
[EDITOR'S NOTE: we may want to add definitions for the different
kinds of interfaces that are important here.]
[GF: Interfaces may be covered by Micahel Welzl's companion
document?]
Transport Service Feature: a specific end-to-end feature that a Transport Service Feature: a specific end-to-end feature that a
transport service provides to its clients. Examples include transport service provides to its clients. Examples include
confidentiality, reliable delivery, ordered delivery, message- confidentiality, reliable delivery, ordered delivery, message-
versus-stream orientation, etc. versus-stream orientation, etc.
Transport Service: a set of transport service features, without an Transport Service: a set of transport service features, without an
association to any given framing protocol, which provides a association to any given framing protocol, which provides a
complete service to an application. complete service to an application.
Transport Protocol: an implementation that provides one or more Transport Protocol: an implementation that provides one or more
different transport services using a specific framing and header different transport services using a specific framing and header
format on the wire. format on the wire.
Transport Protocol Component: an implementation of a transport Transport Protocol Component: an implementation of a transport
service feature within a protocol. service feature within a protocol.
Transport Service Instance: an arrangement of transport protocols Transport Service Instance: an arrangement of transport protocols
with a selected set of features and configuration parameters that with a selected set of features and configuration parameters that
implements a single transport service, e.g. a protocol stack (RTP implements a single transport service, e.g., a protocol stack (RTP
over UDP). over UDP).
Application: an entity that uses the transport layer for end-to-end Application: an entity that uses the transport layer for end-to-end
delivery data across the network (this may also be an upper layer delivery data across the network (this may also be an upper layer
protocol or tunnel encapsulation). protocol or tunnel encapsulation).
3. Existing Transport Protocols 3. Transport Service Features
This section provides a list of known IETF transport protocol and Transport protocols can be differentiated by the features of the
transport protocol frameworks. services they provide.
3.1. Transport Control Protocol (TCP) One fundamental feature is whether a transport offers a service that
divides the data into transmission units based on network packets
(known as a Datagram service), or whether it combines and segments
data across multiple packets (e.g., the Stream service provided by
TCP).
Another fundamental feature is whether a transport requires a control
exchange across the network at setup (e.g., TCP), or whether it
connection-less (e.g., UDP).
A transport service can also offer reliability, for instance, SCTP
offers a message-based service providing full or partial reliability
and allowing to minimize the head of line blocking due to the support
of unordered and unordered message delivery within multiple streams,
UDP-Lite and DCCP provide partial integrity protection.
A transport service can provide congestion control (see Section 3.1).
TCP and SCTP provide congestion control for use in the Internet,
whereas UDP leaves this function to the upper layer protocol that
uses UDP. DCCP offers a range of congestion control approaches and
LEDBAT can support low-priority "scavenger" communication, intending
to defer use of capacity to other Internet flows sharing a congested
bottleneck.
Transport services may be unidirectional or bidirectional, to a
single a single endpoint, to one of multiple endpoints, or multicast
simultaneously to multiple endpoints.
The service offered by transport protocols and frameworks can also be
differentiated in many other ways.
3.1. Congestion Control
Congestion control is critical to the stable operation of the
Internet, applications and other protocols that choose to use a
datagram protocol (e.g., UDP or UDP-Lite) need to employ mechanisms
to prevent congestion collapse and to establish some degree of
fairness with concurrent traffic.
A variety of techniques are used to provide congestion control in the
Internet. Each technique requires that the protocol provide a method
for deriving the metric the congestion control algorithm uses to
detect congestion and the property of a packet it uses to determine
when to send. Given these relatively wide constraints, the
congestion control techniques that can be applied by different
transport protocols are largely orthogonal to the choice of transport
protocols themselves. This section provides an overview of the
congestion control techniques available to the protocols described in
Section 4.
Most commonly deployed congestion control mechanisms use one of three
mechanisms to detect congestion:
o detection of loss, which is interpreted as a congestion signal;
o Explicit Congestion Notification (ECN) [RFC3168] to provide
explicit signaling of congestion without inducing loss (see
[I-D.ietf-aqm-ecn-benefits]); and/or
o a retransmission timer with exponential back-off.
Protocols such as SCTP and TCP [RFC5681] that use sliding-window-
based receiver flow control commonly use a separate congestion window
for congestion control. Each time congestion is detected, this
separate congestion window is reduced. Data in flight is capped to
the minimum of the two windows. This approach is also used by DCCP
CCID-2 for datagram congestion control.
Rate-based methods have also been defined based on the loss ratio and
observed round trip time, such as TFRC [RFC5348] and TFRC-SP
[RFC4828]. These methods utlise a throughput equation to determine
the maximum acceptable rate. Such methods are used with DCCP CCID-3
[RFC4342] and CCID-4 [RFC5622], WEBRC [RFC3738], and other
applications.
In addition, a congestion control mechanism may react to changes in
delay as an indication for congestion. Delay-based congestion
detection methods tend to induce less loss than loss-based methods,
and therefore generally do not compete well with them across shared
bottleneck links. However, such methods, such as LEDBAT [RFC6824],
are are deployed in the Internet for scavenger traffic, which will
use unused capacity but readily yield to presumably interactive or
otherwise higher-priority, loss-based congestion-controlled traffic.
4. Existing Transport Protocols
This section provides a list of known IETF transport protocols and
transport protocol frameworks. It does not make an assessment about
whether specific implementations of protocols are fully compliant to
current IETF specifications.
4.1. Transport Control Protocol (TCP)
TCP is an IETF standards track transport protocol. [RFC0793] TCP is an IETF standards track transport protocol. [RFC0793]
introduces TCP as follows: "The Transmission Control Protocol (TCP) introduces TCP as follows: "The Transmission Control Protocol (TCP)
is intended for use as a highly reliable host-to-host protocol is intended for use as a highly reliable host-to-host protocol
between hosts in packet-switched computer communication networks, and between hosts in packet-switched computer communication networks, and
in interconnected systems of such networks." Since its introduction, in interconnected systems of such networks." Since its introduction,
TCP has become the default connection-oriented, stream-based TCP has become the default connection- oriented, stream-based
transport protocol in the Internet. It is widely implemented by transport protocol in the Internet. It is widely implemented by
endpoints and widely used by common applications. endpoints and widely used by common applications.
3.1.1. Protocol Description 4.1.1. Protocol Description
TCP is a connection-oriented protocol, providing a three way TCP is a connection-oriented protocol, providing a three way
handshake to allow a client and server to set up a connection and handshake to allow a client and server to set up a connection and
negotiate features, and mechanisms for orderly completion and negotiate features, and mechanisms for orderly completion and
immediate teardown of a connection. TCP is defined by a family of immediate teardown of a connection. TCP is defined by a family of
RFCs [RFC4614]. RFCs [RFC4614].
TCP provides multiplexing to multiple sockets on each host using port TCP provides multiplexing to multiple sockets on each host using port
numbers.] A similar approach is adopted by other IETF-defined numbers. A similar approach is adopted by other IETF-defined
transports. An active TCP session is identified by its four-tuple of transports. An active TCP session is identified by its four-tuple of
local and remote IP addresses and local port and remote port numbers. local and remote IP addresses and local port and remote port numbers.
The destination port during connection setup is often used to The destination port during connection setup is often used to
indicate the requested service. indicate the requested service.
TCP partitions a continuous stream of bytes into segments, sized to TCP partitions a continuous stream of bytes into segments, sized to
fit in IP packets. ICMP-based PathMTU discovery [RFC1191][RFC1981] fit in IP packets. ICMP-based Path MTU discovery [RFC1191][RFC1981]
as well as Packetization Layer Path MTU Discovery (PMTUD) [RFC4821] as well as Packetization Layer Path MTU Discovery (PMTUD) [RFC4821]
are supported. have been defined by the IETF.
Each byte in the stream is identified by a sequence number. The Each byte in the stream is identified by a sequence number. The
sequence number is used to order segments on receipt, to identify sequence number is used to order segments on receipt, to identify
segments in acknowledgments, and to detect unacknowledged segments segments in acknowledgments, and to detect unacknowledged segments
for retransmission. This is the basis of the reliable, ordered for retransmission. This is the basis of the reliable, ordered
delivery of data in a TCP stream. TCP Selective Acknowledgment delivery of data in a TCP stream. TCP Selective Acknowledgment
[RFC2018] extends this mechanism by making it possible to identify [RFC2018] extends this mechanism by making it possible to identify
missing segments more precisely, reducing spurious retransmission. missing segments more precisely, reducing spurious retransmission.
Receiver flow control is provided by a sliding window: limiting the Receiver flow control is provided by a sliding window: limiting the
amount of unacknowledged data that can be outstanding at a given amount of unacknowledged data that can be outstanding at a given
time. The window scale option [RFC7323] allows a receiver to use time. The window scale option [RFC7323] allows a receiver to use
windows greater than 64KB. windows greater than 64KB.
All TCP senders provide Congestion Control [RFC5681]: This uses a TCP provides congestion control [RFC5681], described further in
separate window, where each time congestion is detected, this Section 3.1 below.
congestion window is reduced. Most of the used congestion control
mechanisms use one of three mechanisms to detect congestion: A
retransmission timer (with exponential back-up), detection of loss
(interpreted as a congestion signal), or Explicit Congestion
Notification (ECN) [RFC3168] to provide early signaling (see
[I-D.ietf-aqm-ecn-benefits]). In addition, a congestion control
mechanism may react to changes in delay as an early indication for
congestion.
A TCP protocol instance can be extended [RFC4614] and tuned. Some TCP protocol instances can be extended [RFC4614] and tuned. Some
features are sender-side only, requiring no negotiation with the features are sender-side only, requiring no negotiation with the
receiver; some are receiver-side only, some are explicitly negotiated receiver; some are receiver-side only, some are explicitly negotiated
during connection setup. during connection setup.
By default, TCP segment partitioning uses Nagle's algorithm [RFC0896] By default, TCP segment partitioning uses Nagle's algorithm [RFC0896]
to buffer data at the sender into large segments, potentially to buffer data at the sender into large segments, potentially
incurring sender-side buffering delay; this algorithm can be disabled incurring sender-side buffering delay; this algorithm can be disabled
by the sender to transmit more immediately, e.g., to reduce latency by the sender to transmit more immediately, e.g., to reduce latency
for interactive sessions. for interactive sessions.
TCP provides a push and a urgent function to enable data to be TCP provides an "urgent data" function for limited out-of-order
directly accessed by the receiver wihout having to wait for in-order delivery of the data. This function is deprecated [RFC6093].
delivery of the data. However, [RFC6093] does not recommend the use
of the urgent flag due to the range of TCP implementations that
process TCP urgent indications differently.
A checksum provides an Integrity Check and is mandatory across the A mandatory checksum provides a basic integrity check against
entire packet. This check protects from delivery of corrupted data misdelivery and data corruption over the entire packet. Applications
and miselivery of packets to the wrong endpoint. This check is that require end to end integrity of data are recommended to include
relatively weak, applications that require end to end integrity of a stronger integrity check of their payload data. The TCP checksum
data are recommended to include a stronger integrity check of their does not support partial corruption protection (as in DCCP/UDP-Lite).
payload data. The TCP checksum does not support partial corruption
protection (as in DCCP/UDP-Lite).
TCP only supports unicast connections. TCP supports only unicast connections.
3.1.2. Interface description 4.1.2. Interface description
A User/TCP Interface is defined in [RFC0793] providing six user A User/TCP Interface is defined in [RFC0793] providing six user
commands: Open, Send, Receive, Close, Status. This interface does commands: Open, Send, Receive, Close, Status. This interface does
not describe configuration of TCP options or parameters beside use of not describe configuration of TCP options or parameters beside use of
the PUSH and URGENT flags. the PUSH and URGENT flags.
[RFC1122] describes extensions of the TCP/application layer interface [RFC1122] describes extensions of the TCP/application layer interface
for 1) reporting soft errors such as reception fo ICMP error for:
messages, extensive retransmission or urgent pointer advance, 2)
providing a possibility to specify the Type-of-Service (TOS) for o reporting soft errors such as reception of ICMP error messages,
segments, 3) providing a fush call to empty the TCP send queue, and extensive retransmission or urgent pointer advance,
4) multihoming support.
o providing a possibility to specify the Differentiated Services
Code Point (DSCP) (formerly, the Type-of-Service, TOS) for
segments,
o providing a flush call to empty the TCP send queue, and
o multihoming support.
In API implementations derived from the BSD Sockets API, TCP sockets In API implementations derived from the BSD Sockets API, TCP sockets
are created using the "SOCK_STREAM" socket type as described in the are created using the "SOCK_STREAM" socket type as described in the
IEEE Portable Operating System Interface (POSIX) Base Specifications IEEE Portable Operating System Interface (POSIX) Base Specifications
[POSIX]. The features used by a protocol instance may be set and [POSIX]. The features used by a protocol instance may be set and
tuned via this API. However, there is no RFC that documents this tuned via this API. There are current no documents in the RFC Series
interface. that describe this interface.
3.1.3. Transport Features 4.1.3. Transport Features
The transport features provided by TCP are: The transport features provided by TCP are:
[EDITOR'S NOTE: expand each of these slightly]
o unicast transport o unicast transport
o connection setup with feature negotiation and application-to-port o connection setup with feature negotiation and application-to-port
mapping, implemented using SYN segments and the TCP option field mapping, implemented using SYN segments and the TCP option field
to negotiate features. to negotiate features.
o port multiplexing: each TCP session is uniquely identified by a o port multiplexing: each TCP session is uniquely identified by a
combination of the ports and IP address fields. combination of the ports and IP address fields.
o Uni-or bidirectional communication o Uni-or bidirectional communication.
o stream-oriented delivery in a single stream o stream-oriented delivery in a single stream.
o fully reliable delivery, implemented using ACKs sent from the o fully reliable delivery, implemented using ACKs sent from the
receiver to confirm delivery. receiver to confirm delivery.
o error detection: a segment checksum verifies delivery to the o error detection: a segment checksum verifies delivery to the
correct endpoint and integrity of the data and options. correct endpoint and integrity of the data and options.
o segmentation: packets are fragmented to a negotiated maximum o segmentation: packets are fragmented to a negotiated maximum
segment size, further constrained by the effective MTU from PMTUD. segment size, further constrained by the effective MTU from PMTUD.
o data bundling, an optional mechanism that uses Nagle's algorithm o data bundling, an optional mechanism that uses Nagle's algorithm
to coalesce data sent within the same RTT into full-sized to coalesce data sent within the same RTT into full-sized
segments. segments.
o flow control using a window-based mechanism, where the receiver o flow control using a window-based mechanism, where the receiver
advertises the window that it is willing to buffer. advertises the window that it is willing to buffer.
o congestion control: a window-based method that uses AIMD to o congestion control: a window-based method that uses Additive
control the sending rate and to conservatively choose a rate after Increase Multiplicative Decrease (AIMD) to control the sending
congestion is detected. rate and to conservatively choose a rate after congestion is
detected.
3.2. Multipath TCP (MPTCP) 4.2. Multipath TCP (MPTCP)
Multipath TCP [RFC6824] is an extension for TCP to support multi- Multipath TCP [RFC6824] is an extension for TCP to support multi-
homing. It is designed to be as transparent as possible to middle- homing. It is designed to be as transparent as possible to middle-
boxes. It does so by establishing regular TCP flows between a pair boxes. It does so by establishing regular TCP flows between a pair
of source/destination endpoints, and multiplexing the application's of source/destination endpoints, and multiplexing the application's
stream over these flows. stream over these flows.
3.2.1. Protocol Description 4.2.1. Protocol Description
MPTCP uses TCP options for its control plane. They are used to MPTCP uses TCP options for its control plane. They are used to
signal multipath capabilities, as well as to negotiate data sequence signal multipath capabilities, as well as to negotiate data sequence
numbers, and advertise other available IP addresses and establish new numbers, and advertise other available IP addresses and establish new
sessions between pairs of endpoints. sessions between pairs of endpoints.
3.2.2. Interface Description 4.2.2. Interface Description
By default, MPTCP exposes the same interface as TCP to the By default, MPTCP exposes the same interface as TCP to the
application. [RFC6897] however describes a richer API for MPTCP- application. [RFC6897] however describes a richer API for MPTCP-
aware applications. aware applications.
This Basic API describes how an application can This Basic API describes how an application can:
o enable or disable MPTCP; o enable or disable MPTCP.
o bind a socket to one or more selected local endpoints; o bind a socket to one or more selected local endpoints.
o query local and remote endpoint addresses; o query local and remote endpoint addresses.
o get a unique connection identifier (similar to an address-port o get a unique connection identifier (similar to an address-port
pair for TCP). pair for TCP).
The document also recommends the use of extensions defined for SCTP The document also recommends the use of extensions defined for SCTP
[RFC6458] (see next section) to support multihoming. [RFC6458] (see next section) to support multihoming.
3.2.3. Transport features 4.2.3. Transport features
As an extension to TCP, MPTCP provides mostly the same features. By As an extension to TCP, MPTCP provides mostly the same features. By
establishing multiple sessions between available endpoints, it can establishing multiple sessions between available endpoints, it can
additionally provide soft failover solutions should one of the paths additionally provide soft failover solutions should one of the paths
become unusable. In addition, by multiplexing one byte stream over become unusable. In addition, by multiplexing one byte stream over
separate paths, it can achieve a higher throughput than TCP in separate paths, it can achieve a higher throughput than TCP in
certain situations (note however that coupled congestion control certain situations. Note, however, that coupled congestion control
[RFC6356] might limit this benefit to maintain fairness to other [RFC6356] might limit this benefit to maintain fairness to other
flows at the bottleneck). When aggregating capacity over multiple flows at the bottleneck. When aggregating capacity over multiple
paths, and depending on the way packets are scheduled on each TCP paths, and depending on the way packets are scheduled on each TCP
subflow, an additional delay and higher jitter might be observed subflow, an additional delay and higher jitter might be observed
observed before in-order delivery of data to the applications. observed before in-order delivery of data to the applications.
The transport features provided by MPTCP in addition to TCP therefore The transport features provided by MPTCP in addition to TCP therefore
are: are:
o congestion control with load balancing over mutiple connections. o congestion control with load balancing over multiple connections.
o endpoint multiplexing of a single byte stream (higher throughput). o endpoint multiplexing of a single byte stream (higher throughput).
o address family multiplexing: sub-flows can be started over IPv4 or o address family multiplexing: sub-flows can be started over IPv4 or
IPv6 for the same session. IPv6 for the same session.
o resilience to network failure and/or handover. o resilience to network failure and/or handover.
[AUTHOR'S NOTE: it is unclear whether MPTCP has to provide data 4.3. Stream Control Transmission Protocol (SCTP)
bundling.]
3.3. Stream Control Transmission Protocol (SCTP) SCTP is a message-oriented IETF standards track transport protocol.
The base protocol is specified in [RFC4960]. It supports multi-
homing and path failover to provide resilience to path failures. An
SCTP association has multiple streams in each direction, providing
in-sequence delivery of user messages within each stream. This
allows it to minimize head of line blocking. SCTP supports multiple
stream scheduling schemes controlling stream multiplexing, including
priority and fair weighting schemes.
SCTP is a message-oriented standards track transport protocol. The SCTP is extensible. Currently defined extensions include mechanisms
base protocol is specified in [RFC4960]. It supports multi-homing to for dynamic re-configuration of streams [RFC6525] and IP addresses
handle path failures. It also optionally supports path failover to
provide resilliance to path failures. An SCTP association has [RFC5061]. Furthermore, the extension specified in [RFC3758]
multiple unidirectional streams in each direction and provides in- introduces the concept of partial reliability for user messages.
sequence delivery of user messages only within each stream. This
allows it to minimize head of line blocking. SCTP is extensible and
the currently defined extensions include mechanisms for dynamic re-
configurations of streams [RFC6525] and IP-addresses [RFC5061].
Furthermore, the extension specified in [RFC3758] introduces the
concept of partial reliability for user messages.
SCTP was originally developed for transporting telephony signalling SCTP was originally developed for transporting telephony signalling
messages and is deployed in telephony signalling networks, especially messages and is deployed in telephony signalling networks, especially
in mobile telephony networks. It can also be used for other in mobile telephony networks. It can also be used for other
services, for example in the WebRTC framework for data channels and services, for example in the WebRTC framework for data channels. It
is therefore deployed in all WEB-browsers supporting WebRTC. is therefore deployed in all Web browsers supporting WebRTC.
3.3.1. Protocol Description 4.3.1. Protocol Description
SCTP is a connection-oriented protocol using a four way handshake to SCTP is a connection-oriented protocol using a four way handshake to
establish an SCTP association and a three way message exchange to establish an SCTP association, and a three way message exchange to
gracefully shut it down. It uses the same port number concept as gracefully shut it down. It uses the same port number concept as
DCCP, TCP, UDP, and UDP-Lite, and only supports unicast. DCCP, TCP, UDP, and UDP-Lite. SCTP only supports unicast.
SCTP uses the 32-bit CRC32c for protecting SCTP packets against bit SCTP uses the 32-bit CRC32c for protecting SCTP packets against bit
errors and miselivery of packets to the wrong endpoint. This is errors and misdelivery of packets to an unintended endpoint. This is
stronger than the 16-bit checksums used by TCP or UDP. However, a stronger than the 16-bit checksums used by TCP or UDP. However,
partial checksum coverage, as provided by DCCP or UDP-Lite is not partial checksum coverage as provided by DCCP or UDP-Lite is not
supported. supported.
SCTP has been designed with extensibility in mind. Each SCTP packet SCTP has been designed with extensibility in mind. Each SCTP packet
starts with a single common header containing the port numbers, a starts with a single common header containing the port numbers, a
verification tag and the CRC32c checksum. This common header is verification tag and the CRC32c checksum. This common header is
followed by a sequence of chunks. Each chunk consists of a type followed by a sequence of chunks. Each chunk consists of a type
field, flags, a length field and a value. [RFC4960] defines how a field, flags, a length field and a value. [RFC4960] defines how a
receiver processes chunks with an unknown chunk type. The support of receiver processes chunks with an unknown chunk type. The support of
extensions can be negotiated during the SCTP handshake. extensions can be negotiated during the SCTP handshake.
SCTP provides a message-oriented service. Multiple small user SCTP provides a message-oriented service. Multiple small user
messages can be bundled into a single SCTP packet to improve the messages can be bundled into a single SCTP packet to improve
efficiency. For example, this bundling may be done by delaying user efficiency. For example, this bundling may be done by delaying user
messages at the sender similar to the Nagle algorithm used by TCP. messages at the sender, similar to Nagle's algorithm used by TCP.
User messages which would result in IP packets larger than the MTU User messages which would result in IP packets larger than the MTU
will be fragmented at the sender and reassembled at the receiver. will be fragmented at the sender and reassembled at the receiver.
There is no protocol limit on the user message size. ICMP-based path There is no protocol limit on the user message size. ICMP-based path
MTU discovery as specified for IPv4 in [RFC1191] and for IPv6 in MTU discovery as specified for IPv4 in [RFC1191] and for IPv6 in
[RFC1981] as well as packetization layer path MTU discovery as [RFC1981] as well as packetization layer path MTU discovery as
specified in [RFC4821] with probe packets using the padding chunks specified in [RFC4821] with probe packets using the padding chunks
defined the [RFC4820] are supported. defined in [RFC4820] are supported.
[RFC4960] specifies a TCP friendly congestion control to protect the [RFC4960] specifies TCP-friendly congestion control to protect the
network against overload. SCTP also uses a sliding window flow network against overload; see Section 3.1 for more. SCTP also uses
control to protect receivers against overflow. Similar to TCP, SCTP sliding window flow control to protect receivers against overflow.
also supports delaying acknowledgements. [RFC7053] provides a way Similar to TCP, SCTP also supports delaying acknowledgments.
for the sender of user messages to request the immediate sending of [RFC7053] provides a way for the sender of user messages to request
the corresponding acknowledgements. the immediate sending of the corresponding acknowledgments.
Each SCTP association has between 1 and 65536 uni-directional streams Each SCTP association has between 1 and 65536 uni-directional streams
in each direction. The number of streams can be different in each in each direction. The number of streams can be different in each
direction. Every user-message is sent on a particular stream. User direction. Every user message is sent on a particular stream. User
messages can be sent un-ordered or ordered upon request by the upper messages can be sent un- ordered, or ordered upon request by the
layer. Un-ordered messages can be delivered as soon as they are upper layer. Un-ordered messages can be delivered as soon as they
completely received. Ordered messages sent on the same stream are are completely received. Ordered messages sent on the same stream
delivered at the receiver in the same order as sent by the sender. are delivered at the receiver in the same order as sent by the
For user messages not requiring fragmentation, this minimises head of sender. For user messages not requiring fragmentation, this
line blocking. minimizes head of line blocking.
The base protocol defined in [RFC4960] does not allow interleaving of The base protocol defined in [RFC4960] does not allow interleaving of
user-messages, which results in sending a large message on one stream user- messages. Large messages on one stream can therefore block the
can block the sending of user messages on other streams. sending of user messages on other streams.
[I-D.ietf-tsvwg-sctp-ndata] overcomes this limitation. Furthermore, [I-D.ietf-tsvwg-sctp-ndata] overcomes this limitation. This draft
[I-D.ietf-tsvwg-sctp-ndata] specifies multiple algorithms for the also specifies multiple algorithms for the sender side selection of
sender side selection of which streams to send data from supporting a which streams to send data from, supporting a variety of scheduling
variety of scheduling algorithms including priority based methods. algorithms including priority based methods. The stream re-
The stream re-configuration extension defined in [RFC6525] allows configuration extension defined in [RFC6525] allows streams to be
streams to be reset during the lifetime of an association and to reset during the lifetime of an association and to increase the
increase the number of streams, if the number of streams negotiated number of streams, if the number of streams negotiated in the SCTP
in the SCTP handshake becomes insufficient. handshake becomes insufficient.
Each user message sent is either delivered to the receiver or, in Each user message sent is either delivered to the receiver or, in
case of excessive retransmissions, the association is terminated in a case of excessive retransmissions, the association is terminated in a
non-graceful way [RFC4960], similar to TCP behaviour. In addition to non-graceful way [RFC4960], similar to TCP behaviour. In addition to
this reliable transfer, the partial reliability extension [RFC3758] this reliable transfer, the partial reliability extension [RFC3758]
allows a sender to abandon user messages. The application can allows a sender to abandon user messages. The application can
specify the policy for abandoning user messages. Examples for these specify the policy for abandoning user messages. Examples of these
policies defined in [RFC3758] and [RFC7496] are: policies defined in [RFC3758] and [RFC7496] are:
o Limiting the time a user message is dealt with by the sender. o Limiting the time a user message is dealt with by the sender.
o Limiting the number of retransmissions for each fragment of a user o Limiting the number of retransmissions for each fragment of a user
message. If the number of retransmissions is limited to 0, one message. If the number of retransmissions is limited to 0, one
gets a service similar to UDP. gets a service similar to UDP.
o Abandoning messages of lower priority in case of a send buffer o Abandoning messages of lower priority in case of a send buffer
shortage. shortage.
SCTP supports multi-homing. Each SCTP endpoint uses a list of IP- SCTP supports multi-homing. Each SCTP endpoint uses a list of IP-
addresses and a single port number. These addresses can be any addresses and a single port number. These addresses can be any
mixture of IPv4 and IPv6 addresses. These addresses are negotiated mixture of IPv4 and IPv6 addresses. These addresses are negotiated
during the handshake and the address re-configuration extension during the handshake and the address re-configuration extension
specified in [RFC5061] in combination with [RFC4895] can be used to specified in [RFC5061] in combination with [RFC4895] can be used to
change these addresses in an authenticated way during the livetime of change these addresses in an authenticated way during the livetime of
an SCTP association. This allows for transport layer mobility. an SCTP association. This allows for transport layer mobility.
Multiple addresses are used for improved resilience. If a remote Multiple addresses are used for improved resilience. If a remote
address becomes unreachable, the traffic is switched over to a address becomes unreachable, the traffic is switched over to a
reachable one, if one exists. Each SCTP end-point supervises reachable one, if one exists. [I-D.ietf-tsvwg-sctp-failover]
continuously the reachability of all peer addresses using a heartbeat specifies a quicker failover operation reducing the latency of the
mechanism. failover.
For securing user messages, the use of TLS over SCTP has been For securing user messages, the use of TLS over SCTP has been
specified in [RFC3436]. However, this solution does not support all specified in [RFC3436]. However, this solution does not support all
services provided by SCTP (for example un-ordered delivery or partial services provided by SCTP, such as un-ordered delivery or partial
reliability), and therefore the use of DTLS over SCTP has been reliability. Therefore, the use of DTLS over SCTP has been specified
specified in [RFC6083] to overcome these limitations. When using in [RFC6083] to overcome these limitations. When using DTLS over
DTLS over SCTP, the application can use almost all services provided SCTP, the application can use almost all services provided by SCTP.
by SCTP.
[I-D.ietf-tsvwg-natsupp] defines methods for endpoints and [I-D.ietf-tsvwg-natsupp] defines methods for endpoints and
middleboxes to provide support NAT for SCTP over IPv4. For legacy middleboxes to provide support NAT for SCTP over IPv4. For legacy
NAT traversal, [RFC6951] defines the UDP encapsulation of SCTP- NAT traversal, [RFC6951] defines the UDP encapsulation of SCTP-
packets. Alternatively, SCTP packets can be encapsulated in DTLS packets. Alternatively, SCTP packets can be encapsulated in DTLS
packets as specified in [I-D.ietf-tsvwg-sctp-dtls-encaps]. The packets as specified in [I-D.ietf-tsvwg-sctp-dtls-encaps]. The
latter encapsulation is used within the WebRTC context. latter encapsulation is used within the WebRTC context.
SCTP has a well-defined API, described in the next subsection. SCTP has a well-defined API, described in the next subsection.
3.3.2. Interface Description 4.3.2. Interface Description
[RFC4960] defines an abstract API for the base protocol. This API [RFC4960] defines an abstract API for the base protocol. This API
describes the following functions callable by the upper layer of describes the following functions callable by the upper layer of
SCTP: Initialize, Associate, Send, Receive, Receive Unsent Message, SCTP: Initialize, Associate, Send, Receive, Receive Unsent Message,
Receive Unacknowledged Message, Shutdown, Abort, SetPrimary, Status, Receive Unacknowledged Message, Shutdown, Abort, SetPrimary, Status,
Change Heartbeat, Request Heartbeat, Get SRTT Report, Set Failure Change Heartbeat, Request Heartbeat, Get SRTT Report, Set Failure
Threshold, Set Protocol Parameters, and Destroy. The following Threshold, Set Protocol Parameters, and Destroy. The following
notifications are provided by the SCTP stack to the upper layer: notifications are provided by the SCTP stack to the upper layer:
COMMUNICATION UP, DATA ARRIVE, SHUTDOWN COMPLETE, COMMUNICATION LOST, COMMUNICATION UP, DATA ARRIVE, SHUTDOWN COMPLETE, COMMUNICATION LOST,
COMMUNICATION ERROR, RESTART, SEND FAILURE, NETWORK STATUS CHANGE. COMMUNICATION ERROR, RESTART, SEND FAILURE, NETWORK STATUS CHANGE.
An extension to the BSD Sockets API is defined in [RFC6458] and An extension to the BSD Sockets API is defined in [RFC6458] and
covers: covers:
o the base protocol defined in [RFC4960]. The API allows to control o the base protocol defined in [RFC4960]. The API allows control
the local addresses and port numbers and the primary path. over local addresses and port numbers and the primary path.
Furthermore the application has fine control about parameters like Furthermore the application has fine control about parameters like
retransmission thresholds, the path supervision parameters, the retransmission thresholds, the path supervision parameters, the
delayed acknowledgement timeout, and the fragmentation point. The delayed acknowledgment timeout, and the fragmentation point. The
API provides a mechanism to allow the SCTP stack to notify the API provides a mechanism to allow the SCTP stack to notify the
application about event if the application has requested them. application about event if the application has requested them.
These notifications provide Information about status changes of These notifications provide Information about status changes of
the association and each of the peer addresses. In case of send the association and each of the peer addresses. In case of send
failures that application can also be notified and user messages failures, including drop of messages sent unreliably, the
can be returned to the application. When sending user messages, application can also be notified and user messages can be returned
the stream id, a payload protocol identifier, an indication to the application. When sending user messages, the stream id, a
whether ordered delivery is requested or not. These parameters payload protocol identifier, an indication whether ordered
can also be provided on message reception. Additionally a context delivery is requested or not. These parameters can also be
can be provided when sending, which can be use in case of send provided on message reception. Additionally a context can be
failures. The sending of arbitrary large user messages is provided when sending, which can be use in case of send failures.
supported. The sending of arbitrary large user messages is supported.
o the SCTP Partial Reliability extension defined in [RFC3758] to o the SCTP Partial Reliability extension defined in [RFC3758] to
specify for a user message the PR-SCTP policy and the policy specify for a user message the PR-SCTP policy and the policy
specific parameter. specific parameter.
o the SCTP Authentication extension defined in [RFC4895] allowing to o the SCTP Authentication extension defined in [RFC4895] allowing to
manage the shared keys, the HMAC to use, set the chunk types which manage the shared keys, the HMAC to use, set the chunk types which
are only accepted in an authenticated way, and get the list of are only accepted in an authenticated way, and get the list of
chunks which are accepted by the local and remote end point in an chunks which are accepted by the local and remote end point in an
authenticated way. authenticated way.
skipping to change at page 13, line 30 skipping to change at page 14, line 41
outgoing streams and the whole association. It provides also a outgoing streams and the whole association. It provides also a
way to notify the association about the corresponding events. way to notify the association about the corresponding events.
Furthermore the application can increase the number of streams. Furthermore the application can increase the number of streams.
o the UDP Encapsulation of SCTP packets extension defined in o the UDP Encapsulation of SCTP packets extension defined in
[RFC6951]. The API allows the management of the remote UDP [RFC6951]. The API allows the management of the remote UDP
encapsulation port. encapsulation port.
o the SCTP SACK-IMMEDIATELY extension defined in [RFC7053]. The API o the SCTP SACK-IMMEDIATELY extension defined in [RFC7053]. The API
allows the sender of a user message to request the receiver to allows the sender of a user message to request the receiver to
send the corresponding acknowledgement immediately. send the corresponding acknowledgment immediately.
o the additional PR-SCTP policies defined in [RFC7496]. The API o the additional PR-SCTP policies defined in [RFC7496]. The API
allows to enable/disable the PR-SCTP extension, choose the PR-SCTP allows to enable/disable the PR-SCTP extension, choose the PR-SCTP
policies defined in the document and provide statistical policies defined in the document and provide statistical
information about abandoned messages. information about abandoned messages.
Future documents describing SCTP protocol extensions are expected to Future documents describing SCTP protocol extensions are expected to
describe the corresponding BSD Sockets API extension in a "Socket API describe the corresponding BSD Sockets API extension in a "Socket API
Considerations" section. Considerations" section.
skipping to change at page 14, line 15 skipping to change at page 15, line 26
the sockets and the SCTP associations. the sockets and the SCTP associations.
The SCTP stack can provide information to the applications about The SCTP stack can provide information to the applications about
state changes of the individual paths and the association whenever state changes of the individual paths and the association whenever
they occur. These events are delivered similar to user messages but they occur. These events are delivered similar to user messages but
are specifically marked as notifications. are specifically marked as notifications.
New functions have been introduced to support the use of multiple New functions have been introduced to support the use of multiple
local and remote addresses. Additional SCTP-specific send and local and remote addresses. Additional SCTP-specific send and
receive calls have been defined to permit SCTP-specific information receive calls have been defined to permit SCTP-specific information
to be snet without using ancillary data in the form of additional to be sent without using ancillary data in the form of additional
cmsgs. These functions provide support for detecting partial cmsgs. These functions provide support for detecting partial
delivery of user messages and notifications. delivery of user messages and notifications.
The SCTP socket API allows a fine-grained control of the protocol The SCTP socket API allows a fine-grained control of the protocol
behaviour through an extensive set of socket options. behaviour through an extensive set of socket options.
The SCTP kernel implementations of FreeBSD, Linux and Solaris follow The SCTP kernel implementations of FreeBSD, Linux and Solaris follow
mostly the specified extension to the BSD Sockets API for the base mostly the specified extension to the BSD Sockets API for the base
protocol and the corresponding supported protocol extensions. protocol and the corresponding supported protocol extensions.
3.3.3. Transport Features 4.3.3. Transport Features
The transport features provided by SCTP are: The transport features provided by SCTP are:
[GF: This needs to be harmonised with the components for TCP]
o unicast. o unicast.
o connection setup with feature negotiation and application-to-port o connection setup with feature negotiation and application-to-port
mapping. mapping.
o port multiplexing. o port multiplexing.
o message-oriented delivery. o Uni-or bidirectional communication.
o fully reliable or partially reliable delivery. o message-oriented delivery supporting multiple concurrent streams.
o fully reliable, partially reliable, or unreliable delivery.
o ordered and unordered delivery within a stream. o ordered and unordered delivery within a stream.
o support for multiple concurrent streams. o user message fragmentation and reassembly.
o support for stream scheduling prioritization. o support for stream scheduling prioritization.
o flow control.
o congestion control.
o user message bundling. o user message bundling.
o user message fragmentation and reassembly. o flow control using a window-based mechanism.
o congestion control using methods similar to TCP.
o strong error/misdelivery detection (CRC32c). o strong error/misdelivery detection (CRC32c).
o transport layer multihoming for resilience. o transport layer multihoming for resilience.
o transport layer mobility. o transport layer mobility.
3.4. User Datagram Protocol (UDP) o resilience to network failure and/or handover.
4.4. User Datagram Protocol (UDP)
The User Datagram Protocol (UDP) [RFC0768] [RFC2460] is an IETF The User Datagram Protocol (UDP) [RFC0768] [RFC2460] is an IETF
standards track transport protocol. It provides a unidirectional, standards track transport protocol. It provides a unidirectional
datagram protocol that preserves message boundaries. It provides datagram protocol that preserves message boundaries. It provides no
none of the following transport features: error correction, error correction,congestion control, or flow control. It can be used
congestion control, or flow control. It can be used to send to send broadcast datagrams (IPv4) or multicast datagrams (IPv4 and
broadcast datagrams (IPv4) or multicast datagrams (IPv4 and IPv6), in IPv6), in addition to unicast and anycast datagrams. IETF guidance
addition to unicast (and anycast) datagrams. IETF guidance on the on the use of UDP is provided in {{I-D.ietf-tsvwg- rfc5405bis}}. UDP
use of UDP is provided in[I-D.ietf-tsvwg-rfc5405bis]. UDP is widely is widely implemented and widely used by common applications,
implemented and widely used by common applications, including DNS. including DNS.
3.4.1. Protocol Description 4.4.1. Protocol Description
UDP is a connection-less protocol that maintains message boundaries, UDP is a connection-less protocol that maintains message boundaries,
with no connection setup or feature negotiation. The protocol uses with no connection setup or feature negotiation. The protocol uses
independent messages, ordinarily called datagrams. Each stream of independent messages, ordinarily called datagrams. Each stream of
messages is independently managed, therefore retransmission does not messages is independently managed, therefore retransmission does not
hold back data sent using other logical streams. It provides hold back data sent using other logical streams. It provides
detection of payload errors and misdelivery of packets to the wrong detection of payload errors and misdelivery of packets to an
endpoint, either of which result in discard of received datagrams. unintended endpoint, either of which result in discard of received
datagrams, with no indication to the user of the service.
It is possible to create IPv4 UDP datagrams with no checksum, and It is possible to create IPv4 UDP datagrams with no checksum, and
while this is generally discouraged [RFC1122] while this is generally discouraged [RFC1122]
[I-D.ietf-tsvwg-rfc5405bis], certain special cases permit its use. [I-D.ietf-tsvwg-rfc5405bis], certain special cases permit this use.
These datagrams relie on the IPv4 header checksum to protect from These datagrams rely on the IPv4 header checksum to protect from
misdelivery to the wrong endpoint. IPv6 does not by permit UDP misdelivery to an unintended endpoint. IPv6 does not by permit UDP
datagrams with no checksum, although in certain cases this rule may datagrams with no checksum, although in certain cases this rule may
be relaxed [RFC6935]. The checksum support considerations for be relaxed [RFC6935]. The checksum support considerations for
omitting the checksum are defined in [RFC6936]. Note that due to the omitting the checksum are defined in [RFC6936].
relatively weak form of checksum used by UDP, applications that
require end to end integrity of data are recommended to include a
stronger integrity check of their payload data.
It does not provide reliability and does not provide retransmission. UDP does not provide reliability and does not provide retransmission.
This implies messages may be re-ordered, lost, or duplicated in This implies messages may be re-ordered, lost, or duplicated in
transit. transit. Note that due to the relatively weak form of checksum used
by UDP, applications that require end to end integrity of data are
A receiving application that is unable to run sufficiently fast, or recommended to include a stronger integrity check of their payload
frequently, may miss messages since there is no flow control. The data.
lack of congestion handling implies UDP traffic may experience loss
when using an overlaoded path and may cause the loss of messages from
other protocols (e.g., TCP) when sharing the same network path.
[GF: This para isn't needed": Messages with payload errors are Because UDP provides no flow control, a receiving application that is
ordinarily detected by an invalid end- to-end checksum and are unable to run sufficiently fast, or frequently, may miss messages.
discarded before being delivered to an application. UDP-Lite (see The lack of congestion handling implies UDP traffic may experience
[RFC3828], and below) provides the ability for portions of the loss when using an overloaded path, and may cause the loss of
message contents to be exempt from checksum coverage.] messages from other protocols (e.g., TCP) when sharing the same
network path.
On transmission, UDP encapsulates each datagram into an IP packet, On transmission, UDP encapsulates each datagram into an IP packet,
which may in turn be fragmented by IP and are reassembled before which may in turn be fragmented by IP. Fragments are reassembled
delivery to the UDP receiver. before delivery to the UDP receiver.
Applications that need to provide fragmentation or that have other Applications that need to provide fragmentation or that have other
requirements such as receiver flow control, congestion control, requirements such as receiver flow control, congestion control,
PathMTU discovery/PLPMTUD, support for ECN, etc need these to be PathMTU discovery/PLPMTUD, support for ECN, etc need these to be
provided by protocols operating over UDP [I-D.ietf-tsvwg-rfc5405bis]. provided by protocols operating over UDP [I-D.ietf-tsvwg-rfc5405bis].
3.4.2. Interface Description 4.4.2. Interface Description
[RFC0768] describes basic requirements for an API for UDP. Guidance [RFC0768] describes basic requirements for an API for UDP. Guidance
on use of common APIs is provided in [I-D.ietf-tsvwg-rfc5405bis]. on use of common APIs is provided in [I-D.ietf-tsvwg-rfc5405bis].
A UDP endpoint consists of a tuple of (IP address, port number). A UDP endpoint consists of a tuple of (IP address, port number).
Demultiplexing using multiple abstract endpoints (sockets) on the Demultiplexing using multiple abstract endpoints (sockets) on the
same IP address are supported. The same socket may be used by a same IP address are supported. The same socket may be used by a
single server to interact with multiple clients (note: this behavior single server to interact with multiple clients (note: this behavior
differs from TCP, which uses a pair of tuples to identify a differs from TCP, which uses a pair of tuples to identify a
connection). Multiple server instances (processes) that bind the connection). Multiple server instances (processes) that bind the
skipping to change at page 16, line 48 skipping to change at page 18, line 5
implementation arranges to not duplicate the same received unicast implementation arranges to not duplicate the same received unicast
message to multiple server processes. message to multiple server processes.
Many operating systems also allow a UDP socket to be "connected", Many operating systems also allow a UDP socket to be "connected",
i.e., to bind a UDP socket to a specific (remote) UDP endpoint. i.e., to bind a UDP socket to a specific (remote) UDP endpoint.
Unlike TCP's connect primitive, for UDP, this is only a local Unlike TCP's connect primitive, for UDP, this is only a local
operation that serves to simplify the local send/receive functions operation that serves to simplify the local send/receive functions
and to filter the traffic for the specified addresses and ports and to filter the traffic for the specified addresses and ports
[I-D.ietf-tsvwg-rfc5405bis]. [I-D.ietf-tsvwg-rfc5405bis].
3.4.3. Transport Features 4.4.3. Transport Features
The transport features provided by UDP are: The transport features provided by UDP are:
o unicast. o unicast.
o multicast, anycast, or IPv4 broadcast. o multicast, anycast, or IPv4 broadcast.
o port multiplexing. A receiving port can be configured to receive o port multiplexing. A receiving port can be configured to receive
datagrams from multiple senders. datagrams from multiple senders.
o message-oriented delivery. o message-oriented delivery.
o unidirectional or bidirectional. Transmission in each direction o Uni-or bidirectional communication. Transmission in each
is independent. direction is independent.
o non-reliable delivery. o non-reliable delivery.
o non-ordered delivery. o non-ordered delivery.
o IPv6 jumbograms. o error detection: a segment checksum verifies delivery to the
correct endpoint and integrity of the data. This checksum is
o error and misdelivery detection (checksum). optional for IPv4, and optional under specific conditions for IPv6
where all or none of the payload data is protected.
o optional checksum. All or none of the payload data is protected. o IPv6 jumbograms.
3.5. Lightweight User Datagram Protocol (UDP-Lite) 4.5. Lightweight User Datagram Protocol (UDP-Lite)
The Lightweight User Datagram Protocol (UDP-Lite) [RFC3828] is an The Lightweight User Datagram Protocol (UDP-Lite) [RFC3828] is an
IETF standards track transport protocol. It provides a IETF standards track transport protocol. It provides a
unidirectional, datagram protocol that preserves message boundaries. unidirectional, datagram protocol that preserves message boundaries.
IETF guidance on the use of UDP-Lite is provided in IETF guidance on the use of UDP- Lite is provided in
[I-D.ietf-tsvwg-rfc5405bis]. [I-D.ietf-tsvwg-rfc5405bis].
3.5.1. Protocol Description 4.5.1. Protocol Description
UDP-Lite is a connection-less datagram protocol, with no connection
setup or feature negotiation. The protocol use messages, rather than
a byte-stream. Each stream of messages is independently managed,
therefore retransmission does not hold back data sent using other
logical streams.
It provides multiplexing to multiple sockets on each host using port
numbers, and its operation follows that for UDP. An active UDP-Lite
session is identified by its four-tuple of local and remote IP
addresses and local port and remote port numbers.
UDP-Lite changes the semantics of the UDP "payload length" field to Like UDP, UDP-Lite is a connection-less datagram protocol, with no
that of a "checksum coverage length" field, and is identified by a connection setup or feature negotiation. It changes the semantics of
different IP protocol/next-header value. Otherwise, UDP-Lite is the UDP "payload length" field to that of a "checksum coverage
semantically identical to UDP. Applications using UDP-Lite therefore length" field, and is identified by a different IP protocol/next-
can not make assumptions regarding the correctness of the data header value. Otherwise, UDP-Lite is semantically identical to UDP.
received in the insensitive part of the UDP-Lite payload. Applications using UDP-Lite therefore cannot make assumptions
regarding the correctness of the data received in the insensitive
part of the UDP-Lite payload.
As for UDP, mechanisms for receiver flow control, congestion control, In the same way as for UDP, mechanisms for receiver flow control,
PMTU or PLPMTU discovery, support for ECN, etc need to be provided by congestion control, PMTU or PLPMTU discovery, support for ECN, etc
upper layer protocols [I-D.ietf-tsvwg-rfc5405bis]. need to be provided by upper layer protocols
[I-D.ietf-tsvwg-rfc5405bis].
Examples of use include a class of applications that can derive Examples of use include a class of applications that can derive
benefit from having partially-damaged payloads delivered, rather than benefit from having partially-damaged payloads delivered, rather than
discarded. One use is to support error tolerate payload corruption discarded. One use is to support error tolerate payload corruption
when used over paths that include error-prone links, another when used over paths that include error-prone links, another
application is when header integrity checks are required, but payload application is when header integrity checks are required, but payload
integrity is provided by some other mechanism (e.g., [RFC6936]. integrity is provided by some other mechanism (e.g., [RFC6936]).
A UDP-Lite service may support IPv4 broadcast, multicast, anycast and A UDP-Lite service may support IPv4 broadcast, multicast, anycast and
unicast, and IPv6 multicast, anycast and unicast. unicast, and IPv6 multicast, anycast and unicast.
3.5.2. Interface Description 4.5.2. Interface Description
There is no current API specified in the RFC Series, but guidance on There is no API currently specified in the RFC Series, but guidance
use of common APIs is provided in [I-D.ietf-tsvwg-rfc5405bis]. on use of common APIs is provided in [I-D.ietf-tsvwg-rfc5405bis].
The interface of UDP-Lite differs from that of UDP by the addition of The interface of UDP-Lite differs from that of UDP by the addition of
a single (socket) option that communicates a checksum coverage length a single (socket) option that communicates a checksum coverage length
value: at the sender, this specifies the intended checksum coverage, value: at the sender, this specifies the intended checksum coverage,
with the remaining unprotected part of the payload called the "error- with the remaining unprotected part of the payload called the "error-
insensitive part". The checksum coverage may also be made visible to insensitive part". The checksum coverage may also be made visible to
the application via the UDP-Lite MIB module [RFC5097]. the application via the UDP-Lite MIB module [RFC5097].
3.5.3. Transport Features 4.5.3. Transport Features
The transport features provided by UDP-Lite are: The transport features provided by UDP-Lite are:
o unicast. o unicast.
o multicast, anycast, or IPv4 broadcast. o multicast, anycast, or IPv4 broadcast.
o port multiplexing (as for UDP). o port multiplexing (as for UDP).
o message-oriented delivery (as for UDP). o message-oriented delivery (as for UDP).
o Uni-or bidirectional communication. Transmission in each
direction is independent.
o non-reliable delivery (as for UDP). o non-reliable delivery (as for UDP).
o non-ordered delivery (as for UDP). o non-ordered delivery (as for UDP).
o error and misdelivery detection (checksum). o misdelivery detection (the checksum always provides protection
from misdelivery).
o partialor full integrity protection. The checksum coverage field o partial or full integrity protection. The checksum coverage field
indicates the size of the payload data covered by the checksum. indicates the size of the payload data covered by the checksum.
3.6. Datagram Congestion Control Protocol (DCCP) 4.6. Datagram Congestion Control Protocol (DCCP)
Datagram Congestion Control Protocol (DCCP) [RFC4340] is an IETF Datagram Congestion Control Protocol (DCCP) [RFC4340] is an IETF
standards track bidirectional transport protocol that provides standards track bidirectional transport protocol that provides
unicast connections of congestion-controlled messages without unicast connections of congestion-controlled messages without
providing reliability. providing reliability.
The DCCP Problem Statement describes the goals that DCCP sought to The DCCP Problem Statement describes the goals that DCCP sought to
address [RFC4336]. It is suitable for applications that transfer address [RFC4336]. It is suitable for applications that transfer
fairly large amounts of data and that can benefit from control over fairly large amounts of data and that can benefit from control over
the trade off between timeliness and reliability [RFC4336]. the trade off between timeliness and reliability [RFC4336].
It offers low overhead, and many characteristics common to UDP, but DCCP offers low overhead, and many characteristics common to UDP, but
can avoid "Re-inventing the wheel" each time a new multimedia can avoid "re-inventing the wheel" each time a new multimedia
application emerges. Specifically it includes core functions application emerges. Specifically it includes core functions
(feature negotiation, path state management, RTT calculation, PMTUD, (feature negotiation, path state management, RTT calculation, PMTUD,
etc): This allows applications to use a compatible method defining etc): This allows applications to use a compatible method defining
how they send packets and where suitable to choose common algorithms how they send packets and where suitable to choose common algorithms
to manage their functions. Examples of suitable applications include to manage their functions. Examples of suitable applications include
interactive applications, streaming media or on-line games [RFC4336]. interactive applications, streaming media or on-line games [RFC4336].
3.6.1. Protocol Description 4.6.1. Protocol Description
DCCP is a connection-oriented datagram protocol, providing a three DCCP is a connection-oriented datagram protocol, providing a three-
way handshake to allow a client and server to set up a connection, way handshake to allow a client and server to set up a connection,
and mechanisms for orderly completion and immediate teardown of a and mechanisms for orderly completion and immediate teardown of a
connection. The protocol is defined by a family of RFCs. connection. The protocol is defined by a family of RFCs.
It provides multiplexing to multiple sockets at each endpoint using It provides multiplexing to multiple sockets at each endpoint using
port numbers. An active DCCP session is identified by its four-tuple port numbers. An active DCCP session is identified by its four-tuple
of local and remote IP addresses and local port and remote port of local and remote IP addresses and local port and remote port
numbers. At connection setup, DCCP also exchanges the service code numbers. At connection setup, DCCP also exchanges the service code
[RFC5595], a mechanism that allows transport instantiations to [RFC5595], a mechanism that allows transport instantiations to
indicate the service treatment that is expected from the network. indicate the service treatment that is expected from the network.
skipping to change at page 19, line 52 skipping to change at page 21, line 6
the maximum packet size. A DCCP interface allows applications to the maximum packet size. A DCCP interface allows applications to
request fragmentation for packets larger than PMTU, but not larger request fragmentation for packets larger than PMTU, but not larger
than the maximum packet size allowed by the current congestion than the maximum packet size allowed by the current congestion
control mechanism (CCMPS) [RFC4340]. control mechanism (CCMPS) [RFC4340].
Each message is identified by a sequence number. The sequence number Each message is identified by a sequence number. The sequence number
is used to identify segments in acknowledgments, to detect is used to identify segments in acknowledgments, to detect
unacknowledged segments, to measure RTT, etc. The protocol may unacknowledged segments, to measure RTT, etc. The protocol may
support ordered or unordered delivery of data, and does not itself support ordered or unordered delivery of data, and does not itself
provide retransmission. DCCP supports reduced checksum coverage, a provide retransmission. DCCP supports reduced checksum coverage, a
partial integrity mechanisms similar to UDP-lIte. There is also a partial integrity mechanism similar to UDP-Lite. There is also a
Data Checksum option that when enabled, contains a strong CRC, to Data Checksum option that when enabled, contains a strong CRC, to
enable endpoints to detect application data corruption. enable endpoints to detect application data corruption - similar to
SCTP.
Receiver flow control is supported: limiting the amount of Receiver flow control is supported, which limits the amount of
unacknowledged data that can be outstanding at a given time. unacknowledged data that can be outstanding at a given time.
A DCCP protocol instance can be extended [RFC4340] and tuned using A DCCP protocol instance can be extended [RFC4340] and tuned using
features. Some features are sender-side only, requiring no additional features. Some features are sender-side only, requiring
negotiation with the receiver; some are receiver-side only, some are no negotiation with the receiver; some are receiver-side only; and
explicitly negotiated during connection setup. some are explicitly negotiated during connection setup.
A DCCP service is unicast. DCCP service is unicast-only.
DCCP supports negotiation of the congestion control profile, to It supports negotiation of the congestion control profile, to provide
provide Plug and Play congestion control mechanisms. Examples of plug- and-play congestion control mechanisms. Examples of specified
specified profiles include [RFC4341] [RFC4342] [RFC5662]. All IETF- profiles include "TCP-like" [RFC4341], "TCP-friendly" [RFC4342], and
defined methods provide Congestion Control. "TCP-friendly for small packets" [RFC5622]. Additional mechanisms
are recorded in an IANA registry.
DCCP use a Connect packet to initiate a session, and permits half- DCCP uses a Connect packet to initiate a session, and permits half-
connections that allow each client to choose the features it wishes connections that allow each client to choose the features it wishes
to support. Simultaneous open [RFC5596], as in TCP, can enable to support. Simultaneous open [RFC5596], as in TCP, can enable
interoperability in the presence of middleboxes. The Connect packet interoperability in the presence of middleboxes. The Connect packet
includes a Service Code field [RFC5595] designed to allow middle includes a Service Code field [RFC5595] designed to allow middleboxes
boxes and endpoints to identify the characteristics required by a and endpoints to identify the characteristics required by a session.
session.
A lightweight UDP-based encapsulation (DCCP-UDP) has been defined A lightweight UDP-based encapsulation (DCCP-UDP) has been defined
[RFC6773] that permits DCCP to be used over paths where it is not [RFC6773] that permits DCCP to be used over paths where DCCP is not
natively supported. Support in NAPT/NATs is defined in [RFC4340] and natively supported. Support in NAPT/NATs is defined in [RFC4340] and
[RFC5595]. [RFC5595].
Upper layer protocols specified on top of DCCP include: DTLS Upper layer protocols specified on top of DCCP include DTLS
[RFC5595], RTP [RFC5672], ICE/SDP [RFC6773]. [RFC5595], RTP [RFC5672], ICE/SDP [RFC6773].
A common packet format has allowed tools to evolve that can read and A common packet format has allowed tools to evolve that can read and
interpret DCCP packets (e.g. Wireshark). interpret DCCP packets (e.g., Wireshark).
3.6.2. Interface Description 4.6.2. Interface Description
API characteristics include: - Datagram transmission. - Notification API characteristics include: - Datagram transmission. - Notification
of the current maximum packet size. - Send and reception of zero- of the current maximum packet size. - Send and reception of zero-
length payloads. - Slow Receiver flow control at a receiver. - length payloads. - Slow Receiver flow control at a receiver. -
Detect a Slow receiver at the sender. ability to detect a slow receiver at the sender.
There is no current API curremntly specified in the RFC Series. There is no API currently specified in the RFC Series.
3.6.3. Transport Features 4.6.3. Transport Features
The transport features provided by DCCP are: The transport features provided by DCCP are:
o unicast. o unicast transport.
o connection setup with feature negotiation and application-to-port o connection setup with feature negotiation and application-to-port
mapping. mapping.
o Service Codes. Identifies the upper layer service to the endpoint o Service Codes. Identifies the upper layer service to the endpoint
and network. and network.
o port multiplexing. o port multiplexing.
o Uni-or bidirectional communication.
o message-oriented delivery. o message-oriented delivery.
o non-reliable delivery. o non-reliable delivery.
o ordered delivery. o ordered delivery.
o flow control. The slow receiver function allows a receiver to o flow control. The slow receiver function allows a receiver to
control the rate of the sender. control the rate of the sender.
o drop notification. Allows a receiver to notify which datagrams o drop notification. Allows a receiver to notify which datagrams
were not delivered to the peer upper layer protocol. were not delivered to the peer upper layer protocol.
o timestamps. o timestamps.
o partial and full integrity protection (with optional strong o partial and full integrity protection (with optional strong
integrity check). integrity check).
3.7. Lightweight User Datagram Protocol (UDP-Lite) 4.7. Internet Control Message Protocol (ICMP)
The Lightweight User Datagram Protocol (UDP-Lite) [RFC3828] is an
IETF standards track transport protocol. It provides a
unidirectional, datagram protocol that preserves message boundaries.
IETF guidance on the use of UDP-Lite is provided in
[I-D.ietf-tsvwg-rfc5405bis].
3.7.1. Protocol Description
UDP-Lite is a connection-less datagram protocol, with no connection
setup or feature negotiation. The protocol use messages, rather than
a byte-stream. Each stream of messages is independently managed,
therefore retransmission does not hold back data sent using other
logical streams.
It provides multiplexing to multiple sockets on each host using port
numbers, and its operation follows that for UDP. An active UDP-Lite
session is identified by its four-tuple of local and remote IP
addresses and local port and remote port numbers.
UDP-Lite changes the semantics of the UDP "payload length" field to
that of a "checksum coverage length" field, and is identified by a
different IP protocol/next-header value. Otherwise, UDP-Lite is
semantically identical to UDP. Applications using UDP-Lite therefore
can not make assumptions regarding the correctness of the data
received in the insensitive part of the UDP-Lite payload.
As for UDP, mechanisms for receiver flow control, congestion control,
PMTU or PLPMTU discovery, support for ECN, etc need to be provided by
upper layer protocols [I-D.ietf-tsvwg-rfc5405bis].
Examples of use include a class of applications that can derive
benefit from having partially-damaged payloads delivered, rather than
discarded. One use is to support error tolerate payload corruption
when used over paths that include error-prone links, another
application is when header integrity checks are required, but payload
integrity is provided by some other mechanism (e.g., [RFC6936].
A UDP-Lite service may support IPv4 broadcast, multicast, anycast and
unicast, and IPv6 multicast, anycast and unicast.
3.7.2. Interface Description
There is no current API specified in the RFC Series, but guidance on
use of common APIs is provided in [I-D.ietf-tsvwg-rfc5405bis].
The interface of UDP-Lite differs from that of UDP by the addition of
a single (socket) option that communicates a checksum coverage length
value: at the sender, this specifies the intended checksum coverage,
with the remaining unprotected part of the payload called the "error-
insensitive part". The checksum coverage may also be made visible to
the application via the UDP-Lite MIB module [RFC5097].
3.7.3. Transport Features
The transport features provided by UDP-Lite are:
o unicast
o multicast, anycast, or IPv4 broadcast.
o port multiplexing (as for UDP).
o message-oriented delivery (as for UDP).
o non-reliable delivery(as for UDP).
o non-ordered delivery (as for UDP).
o partial or full integrity protection.
3.8. Internet Control Message Protocol (ICMP)
The Internet Control Message Protocol (ICMP) [RFC0792] for IPv4 and The Internet Control Message Protocol (ICMP) [RFC0792] for IPv4 and
[RFC4433] for IPv6 are IETF standards track protocols. [RFC4433] for IPv6 are IETF standards track protocols.
It provides a conection-less unidirectional protocol that delivers ICMP is a connection-less unidirectional protocol that delivers
individual messages. It provides none of the following transport individual messages, without error correction, congestion control, or
features: error correction, congestion control, or flow control. flow control. Messages may be sent as unicast, IPv4 broadcast or
Some messages may be sent as broadcast datagrams (IPv4) or multicast multicast datagrams (IPv4 and IPv6), in addition to anycast
datagrams (IPv4 and IPv6), in addition to unicast (and anycast)
datagrams. datagrams.
3.8.1. Protocol Description 4.7.1. Protocol Description
ICMP is a conection-less unidirectional protocol that delivers ICMP is a connection-less unidirectional protocol that delivers
individual messages. The protocol uses independent messages, individual messages. The protocol uses independent messages,
ordinarily called datagrams. Each message is required to carry a ordinarily called datagrams. Each message is required to carry a
checksum as an integrity check and to protect from misdelivery to the checksum as an integrity check and to protect from misdelivery to an
wrong endpoint. unintended endpoint.
ICMP messages typically relay diagnostic information from an endpoint ICMP messages typically relay diagnostic information from an endpoint
[RFC1122] or network device [RFC1716] addressed to the sender of a [RFC1122] or network device [RFC1716] addressed to the sender of a
flow. This usually contains the network protocol header of a packet flow. This usually contains the network protocol header of a packet
that encountered the reported issue. Some formats of messages may that encountered a reported issue. Some formats of messages can also
also carry other payload data. Each message carries an integrity carry other payload data. Each message carries an integrity check
check calculated in the same way as UDP. calculated in the same way as for UDP, this checksum is not optional.
The RFC series defines additional IPv6 message formats to support a The RFC series defines additional IPv6 message formats to support a
range of uses. In the case of IPv6 the protocol incorporates range of uses. In the case of IPv6 the protocol incorporates
neighbour discovery [RFC2461] [RFC3971]} (provided by ARP for IPv4) neighbor discovery [RFC2461] [RFC3971]} (provided by ARP for IPv4)
and the Multicast Listener Discovery (MLD) [RFC2710] group management and the Multicast Listener Discovery (MLD) [RFC2710] group management
functions (provided by IGMP for IPv4). functions (provided by IGMP for IPv4).
Reliable transmission can not be assumed. A receiving application Reliable transmission can not be assumed. A receiving application
that is unable to run sufficiently fast, or frequently, may miss that is unable to run sufficiently fast, or frequently, may miss
messages since there is no flow or congestion control. In addition messages since there is no flow or congestion control. In addition
some network devices rate-limit ICMP messages. some network devices rate-limit ICMP messages.
Transport Protocols and upper layer protocols can use ICMP messages Transport Protocols and upper layer protocols can use received ICMP
to help them take appropriate decisions when network or endpoint messages to help them take appropriate decisions when network or
errors are reported. For example to implement, ICMP-based PathMTU endpoint errors are reported. For example to implement, ICMP-based
discovery [RFC1191][RFC1981] or assist in Packetization Layer Path Path MTU discovery [RFC1191][RFC1981] or assist in Packetization
MTU Discovery (PMTUD) [RFC4821]. Such reactions to received messages Layer Path MTU Discovery (PMTUD) [RFC4821]. Such reactions to
needs to protects from off-path data injection received messages need to protects from off-path data injection
[I-D.ietf-tsvwg-rfc5405bis], avoiding an application receiving [I-D.ietf-tsvwg-rfc5405bis], avoiding an application receiving
packets that were created by an unauthorized third party. An packets that were created by an unauthorized third party. An
application therefore needs to ensure that aLL messaged are application therefore needs to ensure that all messages are
appropriately validated, by checking the payload of the messages to appropriately validated, by checking the payload of the messages to
ensure these are received in response to actually transmitted traffic ensure these are received in response to actually transmitted traffic
(e.g., a reported error condition that corresponds to a UDP datagram (e.g., a reported error condition that corresponds to a UDP datagram
or TCP segment was actually sent by the application). This requires or TCP segment was actually sent by the application). This requires
context [RFC6056], such as local state about communication instances context [RFC6056], such as local state about communication instances
to each destination (e.g., in the TCP, DCCP, or SCTP protocols). to each destination (e.g., in the TCP, DCCP, or SCTP protocols).
This state is not always maintained by UDP-based applications This state is not always maintained by UDP-based applications
[I-D.ietf-tsvwg-rfc5405bis]. [I-D.ietf-tsvwg-rfc5405bis].
Any response to ICMP error messages ought to be robust to temporary Any response to ICMP error messages ought to be robust to temporary
routing failures (sometimes called "soft errors"), e.g., transient routing failures (sometimes called "soft errors"), e.g., transient
ICMP "unreachable" messages ought to not normally cause a ICMP "unreachable" messages ought to not normally cause a
communication abort [RFC5461] [I-D.ietf-tsvwg-rfc5405bis]. communication abort [RFC5461] [I-D.ietf-tsvwg-rfc5405bis].
3.8.2. Interface Description 4.7.2. Interface Description
ICMP processing is integrated into many connection-oriented ICMP processing is integrated into many connection-oriented
transports, but like other functions needs to be provided by an transports, but like other functions needs to be provided by an
upper-layer protocol when using UDP and UDP-Lite. On some stacks, a upper-layer protocol when using UDP and UDP-Lite. On some stacks, a
bound socket also allows a UDP application to be notified when ICMP bound socket also allows a UDP application to be notified when ICMP
error messages are received for its transmissions error messages are received for its transmissions
[I-D.ietf-tsvwg-rfc5405bis]. [I-D.ietf-tsvwg-rfc5405bis].
3.8.3. Transport Features 4.7.3. Transport Features
The transport features provided by ICMP are: The transport features provided by ICMP are:
o unidirectional. o unidirectional.
o multicast, anycast and IP4 broadcast. o multicast, anycast and IP4 broadcast.
o message-oriented delivery. o message-oriented delivery.
o non-reliable delivery. o non-reliable delivery.
o non-ordered delivery. o non-ordered delivery.
o error and misdelivery detection (checksum). o error and misdelivery detection (checksum).
3.9. Realtime Transport Protocol (RTP) 4.8. Realtime Transport Protocol (RTP)
RTP provides an end-to-end network transport service, suitable for RTP provides an end-to-end network transport service, suitable for
applications transmitting real-time data, such as audio, video or applications transmitting real-time data, such as audio, video or
data, over multicast or unicast network services, including TCP, UDP, data, over multicast or unicast network services, including TCP, UDP,
UDP-Lite, or DCCP. UDP-Lite, or DCCP.
[EDITOR'S NOTE: Varun Singh signed up as contributor for this 4.8.1. Protocol Description
section. Given the complexity of RTP, suggest to have an abbreviated
section here contrasting RTP with other transports, and focusing on
those features that are RTP-unique. Gorry Fairhurst contributed this
stub section]
3.9.1. Protocol Description
The RTP standard [RFC3550] defines a pair of protocols, RTP and the The RTP standard [RFC3550] defines a pair of protocols, RTP and the
Real Time Control Protocol, RTCP. The transport does not provide Real Time Control Protocol, RTCP. The transport does not provide
connection setup, but relies on out-of-band techniques or associated connection setup, instead relying on out-of-band techniques or
control protocols to setup, negotiate parameters or tear-down a associated control protocols to setup, negotiate parameters or tear
session. down a session.
An RTP sender encapsulates audio/video data into RTP packets to An RTP sender encapsulates audio/video data into RTP packets to
transport media streams. The RFC-series specifies RTP media formats transport media streams. The RFC-series specifies RTP media formats
allow packets to carry a wide range of media, and specifies a wide allow packets to carry a wide range of media, and specifies a wide
range of mulriplexing, error control and other support mechanisms. range of multiplexing, error control and other support mechanisms.
If a frame of media data is large, it will be fragment this into If a frame of media data is large, it will be fragmented into several
several RTP packets. If small, several frames may be bundled into a RTP packets. Likewise, several small frames may be bundled into a
single RTP packet. RTP may runs over a congestion-controlled or non- single RTP packet. RTP may run over a congestion-controlled or non-
congestion-controlled transport protocol. congestion-controlled transport protocol.
An RTP receiver collects RTP packets from network, validates them for An RTP receiver collects RTP packets from network, validates them for
correctness, and sends them to the media decoder input-queue. correctness, and sends them to the media decoder input-queue.
Missing packet detection is performed by the channel decoder. The Missing packet detection is performed by the channel decoder. The
play-out buffer is ordered by time stamp and is used to reorder play-out buffer is ordered by time stamp and is used to reorder
packets. Damaged frames may be repaired before the media payloads packets. Damaged frames may be repaired before the media payloads
are decompressed to display or store the data. are decompressed to display or store the data.
RTCP is an associated control protocol that works with RTP. Both the RTCP is a control protocol that works alongside a RTP flow. Both the
RTP sender and receiver can send RTCP report packets. This is used RTP sender and receiver can send RTCP report packets. This is used
to periodically send control information and report performance. to periodically send control information and report performance.
Based on received RTCP feedback, an RTP sender can adjust the Based on received RTCP feedback, an RTP sender can adjust the
transmission, e.g., perform rate adaptation at the application layer transmission, e.g., perform rate adaptation at the application layer
in the case of congestion. in the case of congestion.
An RTCP receiver report (RTCP RR) is returned to the sender An RTCP receiver report (RTCP RR) is returned to the sender
periodically to report key parameters (e.g, the fraction of packets periodically to report key parameters (e.g, the fraction of packets
lost in the last reporting interval, the cumulative number of packets lost in the last reporting interval, the cumulative number of packets
lost, the highest sequence number received, and the inter-arrival lost, the highest sequence number received, and the inter-arrival
jitter). The RTCP RR packets also contain timing information that jitter). The RTCP RR packets also contain timing information that
allows the sender to estimate the network round trip time (RTT) to allows the sender to estimate the network round trip time (RTT) to
the receivers. the receivers.
The interval between reports sent from each receiver tends to be on The interval between reports sent from each receiver tends to be on
the order of a few seconds on average, although this varies with the the order of a few seconds on average, although this varies with the
session rate, and sub-second reporting intervals are possible for session rate, and sub-second reporting intervals are possible for
high rate sessions. The interval is randomised to avoid high rate sessions. The interval is randomized to avoid
synchronization of reports from multiple receivers. synchronization of reports from multiple receivers.
3.9.2. Interface Description 4.8.2. Interface Description
[EDITOR'S NOTE: to do] There is no standard application programming interface defined for
RTP or RTCP. Implementations are typically tightly integrated with a
particular application, and closely follow the principles of
application level framing and integrated layer processing [ClarkArch]
in media processing [RFC2736], error recovery and concealment, rate
adaptation, and security [RFC7202]. Accordingly, RTP implementations
tend to be targeted at particular application domains (e.g., voice-
over-IP, IPTV, or video conferencing), with a feature set optimised
for that domain, rather than being general purpose implementations of
the protocol.
3.9.3. Transport Features 4.8.3. Transport Features
The transport features provided by RTP are: The transport features provided by RTP are:
o unicast. o unicast transport.
o multicast, anycast or IPv4 broadcast. o multicast, anycast or IPv4 broadcast.
o port multiplexing. o port multiplexing.
o Uni-or bidirectional communication.
o message-oriented delivery. o message-oriented delivery.
o associated protocols for connection setup with feature negotiation o associated protocols for connection setup with feature negotiation
and application-to-port mapping. and application-to-port mapping.
o support for media types and other extensions. o support for media types and other extensions.
o a range of reliability functions, including the possibility of
using packet erasure coding.
o segmentation and aggregation. o segmentation and aggregation.
o performance reporting. o performance reporting.
o drop notification. o drop notification.
o timestamps. o timestamps.
3.10. File Delivery over Unidirectional Transport/Asynchronous Layered 4.9. File Delivery over Unidirectional Transport/Asynchronous Layered
Coding Reliable Multicast (FLUTE/ALC) Coding Reliable Multicast (FLUTE/ALC)
FLUTE/ALC is an IETF standards track protocol specified in [RFC6726] FLUTE/ALC is an IETF standards track protocol specified in [RFC6726]
and [RFC5775],. ALC provides an underlying reliable transport service and [RFC5775]. Asynchronous Layer Coding (ALC) provides an
and FLUTE a file-oriented specialization of the ALC service (e.g., to underlying reliable transport service and FLUTE a file-oriented
carry associated metadata). The [RFC6726] and [RFC5775] protocols specialization of the ALC service (e.g., to carry associated
are non-backward-compatible updates of the [RFC3926] and [RFC3450] metadata). The [RFC6726] and [RFC5775] protocols are non-backward-
experimental protocols; these experimental protocols are currently compatible updates of the [RFC3926] and [RFC3450] experimental
largely deployed in the 3GPP Multimedia Broadcast and Multicast protocols; these experimental protocols are currently largely
Services (MBMS) (see [MBMS], section 7) and similar contexts (e.g., deployed in the 3GPP Multimedia Broadcast and Multicast Services
the Japanese ISDB-Tmm standard). (MBMS) (see [MBMS], section 7) and similar contexts (e.g., the
Japanese ISDB-Tmm standard).
The FLUTE/ALC protocol has been designed to support massively The FLUTE/ALC protocol has been designed to support massively
scalable reliable bulk data dissemination to receiver groups of scalable reliable bulk data dissemination to receiver groups of
arbitrary size using IP Multicast over any type of delivery network, arbitrary size using IP Multicast over any type of delivery network,
including unidirectional networks (e.g., broadcast wireless including unidirectional networks (e.g., broadcast wireless
channels). However, the FLUTE/ALC protocol also supports point-to- channels). However, the FLUTE/ALC protocol also supports point-to-
point unicast transmissions. point unicast transmissions.
FLUTE/ALC bulk data dissemination has been designed for discrete file FLUTE/ALC bulk data dissemination has been designed for discrete file
or memory-based "objects". Transmissions happen either in push mode, or memory-based "objects". Transmissions happen either in push mode,
where content is sent once, or in on-demand mode, where content is where content is sent once, or in on-demand mode, where content is
continuously sent during periods of time that can largely exceed the continuously sent during periods of time that can largely exceed the
average time required to download the session objects (see [RFC5651], average time required to download the session objects (see [RFC5651],
section 4.2). section 4.2).
Altough FLUTE/ALC is not well adapted to byte- and message-streaming, Although FLUTE/ALC is not well adapted to byte- and message-
there is an exception: FLUTE/ALC is used to carry 3GPP Dynamic streaming, there is an exception: FLUTE/ALC is used to carry 3GPP
Adaptive Streaming over HTTP (DASH) when scalability is a requirement Dynamic Adaptive Streaming over HTTP (DASH) when scalability is a
(see [MBMS], section 5.6). In that case, each Audio/Video segment is requirement (see [MBMS], section 5.6). In that case, each Audio/
transmitted as a distinct FLUTE/ALC object in push mode. FLUTE/ALC Video segment is transmitted as a distinct FLUTE/ALC object in push
uses packet erasure coding (also known as Application-Level Forward mode. FLUTE/ALC uses packet erasure coding (also known as
Erasure Correction, or AL-FEC) in a proactive way. The goal of using Application-Level Forward Erasure Correction, or AL-FEC) in a
AL-FEC is both to increase the robustness in front of packet erasures proactive way. The goal of using AL-FEC is both to increase the
and to improve the efficiency of the on-demand service. FLUTE/ALC robustness in front of packet erasures and to improve the efficiency
transmissions can be governed by a congestion control mechanism such of the on-demand service. FLUTE/ALC transmissions can be governed by
as the "Wave and Equation Based Rate Control" (WEBRC) [RFC3738] when a congestion control mechanism such as the "Wave and Equation Based
FLUTE/ALC is used in a layered transmission manner, with several Rate Control" (WEBRC) [RFC3738] when FLUTE/ALC is used in a layered
session channels over which ALC packets are sent. However many transmission manner, with several session channels over which ALC
FLUTE/ALC deployments involve only Constant Bit Rate (CBR) channels packets are sent. However many FLUTE/ALC deployments target pre-
with no competing flows, for which a sender-based rate control provisioned networks and involve only Constant Bit Rate (CBR)
mechanism is sufficient. In any case, FLUTE/ALC's reliability, channels with no competing flows, for which a sender-based rate
delivery mode, congestion control, and flow/rate control mechanisms control mechanism is sufficient. In any case, FLUTE/ALC's
are distinct components that can be separately controlled to meet reliability, delivery mode, congestion control, and flow/rate control
different application needs. mechanisms are distinct components that can be separately controlled
to meet different application needs. Section 4.1 of
[I-D.ietf-tsvwg-rfc5405bis] describes multicast congestion control
requirements for UDP.
3.10.1. Protocol Description 4.9.1. Protocol Description
The FLUTE/ALC protocol works on top of UDP (though it could work on The FLUTE/ALC protocol works on top of UDP (though it could work on
top of any datagram delivery transport protocol), without requiring top of any datagram delivery transport protocol), without requiring
any connectivity from receivers to the sender. Purely unidirectional any connectivity from receivers to the sender. Purely unidirectional
networks are therefore supported by FLUTE/ALC. This guarantees networks are therefore supported by FLUTE/ALC. This guarantees
scalability to an unlimited number of receivers in a session, since scalability to an unlimited number of receivers in a session, since
the sender behaves exactly the same regardness of the number of the sender behaves exactly the same regardless of the number of
receivers. receivers.
FLUTE/ALC supports the transfer of bulk objects such as file or in- FLUTE/ALC supports the transfer of bulk objects such as file or in-
memory content, using either a push or an on-demand mode. in push memory content, using either a push or an on-demand mode. in push
mode, content is sent once to the receivers, while in on-demand mode, mode, content is sent once to the receivers, while in on-demand mode,
content is sent continuously during periods of time that can greatly content is sent continuously during periods of time that can greatly
exceed the average time required to download the session objects. exceed the average time required to download the session objects.
This enables receivers to join a session asynchronously, at their own This enables receivers to join a session asynchronously, at their own
discretion, receive the content and leave the session. In this case, discretion, receive the content and leave the session. In this case,
skipping to change at page 29, line 11 skipping to change at page 29, line 5
packets are sent in those channels at a certain transmission rate, packets are sent in those channels at a certain transmission rate,
with a rate that often differs depending on the channel. FLUTE/ALC with a rate that often differs depending on the channel. FLUTE/ALC
does not mandate nor recommend any strategy to select which ALC does not mandate nor recommend any strategy to select which ALC
packet to send on which channel. FLUTE/ALC can use a multiple rate packet to send on which channel. FLUTE/ALC can use a multiple rate
congestion control building block (e.g., WEBRC) to provide congestion congestion control building block (e.g., WEBRC) to provide congestion
control that is feedback free, where receivers adjust their reception control that is feedback free, where receivers adjust their reception
rates individually by joining and leaving channels associated with rates individually by joining and leaving channels associated with
the session. To that purpose, the ALC header provides a specific the session. To that purpose, the ALC header provides a specific
field to carry congestion control specific information. However field to carry congestion control specific information. However
FLUTE/ALC does not mandate the use of a particular congestion control FLUTE/ALC does not mandate the use of a particular congestion control
mechanism although WEBRC is mandatory to support in case of Internet mechanism although WEBRC is mandatory to support for the Internet
([RFC6726], section 1.1.4). FLUTE/ALC is often used over a network ([RFC6726], section 1.1.4). FLUTE/ALC is often used over a network
path with pre-provisoned capacity [RFC5404] whete theres are no flows path with pre-provisioned capacity [I-D.ietf-tsvwg-rfc5405bis] where
competing for capacity. In this case, a sender-based rate control there are no flows competing for capacity. In this case, a sender-
mechanism and a single channel is sufficient. based rate control mechanism and a single channel is sufficient.
[RFC6584] provides per-packet authentication, integrity, and anti- [RFC6584] provides per-packet authentication, integrity, and anti-
replay protection in the context of the ALC and NORM protocols. replay protection in the context of the ALC and NORM protocols.
Several mechanisms are proposed that seamlessly integrate into these Several mechanisms are proposed that seamlessly integrate into these
protocols using the ALC and NORM header extension mechanisms. protocols using the ALC and NORM header extension mechanisms.
3.10.2. Interface Description 4.9.2. Interface Description
The FLUTE/ALC specification does not describe a specific application The FLUTE/ALC specification does not describe a specific application
programming interface (API) to control protocol operation. programming interface (API) to control protocol operation.
Open source reference implementations of FLUTE/ALC are available at Open source reference implementations of FLUTE/ALC are available at
http://planete-bcast.inrialpes.fr/ (no longer maintained) and http://planete-bcast.inrialpes.fr/ (no longer maintained) and
http://mad.cs.tut.fi/ (no longer maintained), and these http://mad.cs.tut.fi/ (no longer maintained), and these
implementations specify and document their own APIs. Commercial implementations specify and document their own APIs. Commercial
versions are also available, some derived from the above versions are also available, some derived from the above
implementations, with their own API. implementations, with their own API.
3.10.3. Transport Features 4.9.3. Transport Features
The transport features provided by FLUTE/ALC are: The transport features provided by FLUTE/ALC are:
o unicast o unicast
o multicast, anycast or IPv4 broadcast. o multicast, anycast or IPv4 broadcast.
o per-object dynamic meta-data delivery. o per-object dynamic meta-data delivery.
o push delivery or on-demand delivery service. o push delivery or on-demand delivery service.
skipping to change at page 30, line 8 skipping to change at page 29, line 49
o fully reliable or partially reliable delivery (of file or in- o fully reliable or partially reliable delivery (of file or in-
memory objects). memory objects).
o ordered or unordered delivery (of file or in-memory objects). o ordered or unordered delivery (of file or in-memory objects).
o per-packet authentication, integrity, and anti-replay services. o per-packet authentication, integrity, and anti-replay services.
o proactive packet erasure coding (AL-FEC) to recover from packet o proactive packet erasure coding (AL-FEC) to recover from packet
erasures and improve the on-demand delivery service, erasures and improve the on-demand delivery service,
o error detection (through UDP and lower level checksums). o error detection (through UDP).
o congestion control for layered flows (e.g., with WEBRC). o congestion control for layered flows (e.g., with WEBRC).
o rate control transmission in a given channel. 4.10. NACK-Oriented Reliable Multicast (NORM)
3.11. NACK-Oriented Reliable Multicast (NORM)
NORM is an IETF standards track protocol specified in [RFC5740]. The NORM is an IETF standards track protocol specified in [RFC5740]. The
protocol was designed to support reliable bulk data dissemination to protocol was designed to support reliable bulk data dissemination to
receiver groups using IP Multicast but also provides for point-to- receiver groups using IP Multicast but also provides for point-to-
point unicast operation. Its support for bulk data dissemination point unicast operation. Support for bulk data dissemination
includes discrete file or computer memory-based "objects" as well as includes discrete file or computer memory-based "objects" as well as
byte- and message-streaming. NORM is designed to incorporate packet byte- and message-streaming. NORM is designed to incorporate packet
erasure coding as an inherent part of its selective ARQ in response erasure coding as an inherent part of its selective ARQ in response
to receiver negative acknowledgements. The packet erasure coding can to receiver negative acknowledgments. The packet erasure coding can
also be proactively applied for forward protection from packet loss. also be proactively applied for forward protection from packet loss.
NORM transmissions are governed by the TCP-friendly congestion NORM transmissions are governed by the TCP-friendly congestion
control. NORM's reliability, congestion control, and flow control control. NORM's reliability, congestion control, and flow control
mechanism are distinct components and can be separately controlled to mechanism are distinct components and can be separately controlled to
meet different application needs. meet different application needs.
3.11.1. Protocol Description 4.10.1. Protocol Description
[EDITOR'S NOTE: needs to be more clear about the application of FEC
and packet erasure coding; expand ARQ.]
The NORM protocol is encapsulated in UDP datagrams and thus provides The NORM protocol is encapsulated in UDP datagrams and thus provides
multiplexing for multiple sockets on hosts using port numbers. For multiplexing for multiple sockets on hosts using port numbers. For
purposes of loosely coordinated IP Multicast, NORM is not strictly loosely coordinated IP Multicast, NORM is not strictly connection-
connection-oriented although per-sender state is maintained by oriented although per-sender state is maintained by receivers for
receivers for protocol operation. [RFC5740] does not specify a protocol operation. [RFC5740] does not specify a handshake protocol
handshake protocol for connection establishment and separate session for connection establishment and separate session initiation can be
initiation can be used to coordinate port numbers. However, in-band used to coordinate port numbers. However, in-band "client-server"
"client-server" style connection establishment can be accomplished style connection establishment can be accomplished with the NORM
with the NORM congestion control signaling messages using port congestion control signaling messages using port binding techniques
binding techniques like those for TCP client-server connections. like those for TCP client-server connections.
NORM supports bulk "objects" such as file or in-memory content but NORM supports bulk "objects" such as file or in-memory content but
also can treat a stream of data as a logical bulk object for purposes also can treat a stream of data as a logical bulk object for purposes
of packet erasure coding. In the case of stream transport, NORM can of packet erasure coding. In the case of stream transport, NORM can
support either byte streams or message streams where application- support either byte streams or message streams where application-
defined message boundary information is carried in the NORM protocol defined message boundary information is carried in the NORM protocol
messages. This allows the receiver(s) to join/re-join and recover messages. This allows the receiver(s) to join/re- join and recover
message boundaries mid-stream as needed. Application content is message boundaries mid-stream as needed. Application content is
carried and identified by the NORM protocol with encoding symbol carried and identified by the NORM protocol with encoding symbol
identifiers depending upon the Forward Error Correction (FEC) Scheme identifiers depending upon the Forward Error Correction (FEC) Scheme
[RFC3452] configured. NORM uses NACK-based selective ARQ to reliably [RFC3452] configured. NORM uses NACK-based selective ARQ to reliably
deliver the application content to the receiver(s). NORM proactively deliver the application content to the receiver(s). NORM proactively
measures round-trip timing information to scale ARQ timers measures round- trip timing information to scale ARQ timers
appropriately and to support congestion control. For multicast appropriately and to support congestion control. For multicast
operation, timer-based feedback suppression is uses to achieve group operation, timer-based feedback suppression is uses to achieve group
size scaling with low feedback traffic levels. The feedback size scaling with low feedback traffic levels. The feedback
suppression is not applied for unicast operation. suppression is not applied for unicast operation.
NORM uses rate-based congestion control based upon the TCP-Friendly NORM uses rate-based congestion control based upon the TCP-Friendly
Rate Control (TFRC) [RFC4324] principles that are also used in DCCP Rate Control (TFRC) [RFC4324] principles that are also used in DCCP
[RFC4340]. NORM uses control messages to measure RTT and collect [RFC4340]. NORM uses control messages to measure RTT and collect
congestion event (e..g, loss event, ECN event, etc) information from congestion event (e..g, loss event, ECN event, etc) information from
the receiver(s) to support dynamic rate control adjustment. The TCP- the receiver(s) to support dynamic rate control adjustment. The TCP-
Friendly Multicast Congestion Control (TFMCC) [RFC4654] used provides Friendly Multicast Congestion Control (TFMCC) [RFC4654] used provides
some extra features to support multicast but is functionally some extra features to support multicast but is functionally
equivalent to TFRC in the unicast case. equivalent to TFRC in the unicast case.
NORM's reliability mechanism is decoupled from congestion control. NORM's reliability mechanism is decoupled from congestion control.
This allows alternative arrangements of transport services to be This allows alternative arrangements of transport services to be
invoked. For example, fixed-rate reliable delivery can be supported invoked. For example, fixed-rate reliable delivery can be supported
skipping to change at page 31, line 27 skipping to change at page 31, line 16
congestion event (e..g, loss event, ECN event, etc) information from congestion event (e..g, loss event, ECN event, etc) information from
the receiver(s) to support dynamic rate control adjustment. The TCP- the receiver(s) to support dynamic rate control adjustment. The TCP-
Friendly Multicast Congestion Control (TFMCC) [RFC4654] used provides Friendly Multicast Congestion Control (TFMCC) [RFC4654] used provides
some extra features to support multicast but is functionally some extra features to support multicast but is functionally
equivalent to TFRC in the unicast case. equivalent to TFRC in the unicast case.
NORM's reliability mechanism is decoupled from congestion control. NORM's reliability mechanism is decoupled from congestion control.
This allows alternative arrangements of transport services to be This allows alternative arrangements of transport services to be
invoked. For example, fixed-rate reliable delivery can be supported invoked. For example, fixed-rate reliable delivery can be supported
or unreliable (but optionally "better than best effort" via packet or unreliable (but optionally "better than best effort" via packet
erasure coding) delivery with rate-control per TFRC can be achieved. erasure coding) delivery with rate- control per TFRC can be achieved.
Additionally, alternative congestion control techniques may be Additionally, alternative congestion control techniques may be
applied. For example, TFRC rate control with congestion event applied. For example, TFRC rate control with congestion event
detection based on ECN for links with high packet loss (e.g., detection based on ECN for links with high packet loss (e.g.,
wireless) has been implemented and demonstrated with NORM. wireless) has been implemented and demonstrated with NORM.
While NORM is NACK-based for reliability transfer, it also supports a While NORM is NACK-based for reliability transfer, it also supports a
positive acknowledgment (ACK) mechanism that can be used for receiver positive acknowledgment (ACK) mechanism that can be used for receiver
flow control. Again, since this mechanism is decoupled from the flow control. Again, since this mechanism is decoupled from the
reliability and congestion control, applications that have different reliability and congestion control, applications that have different
needs in this aspect can use the protocol differently. One example needs in this aspect can use the protocol differently. One example
is the use of NORM for quasi-reliable delivery where timely delivery is the use of NORM for quasi-reliable delivery where timely delivery
of newer content may be favored over completely reliable delivery of of newer content may be favored over completely reliable delivery of
older content within buffering and RTT constraints. older content within buffering and RTT constraints.
3.11.2. Interface Description 4.10.2. Interface Description
The NORM specification does not describe a specific application The NORM specification does not describe a specific application
programming interface (API) to control protocol operation. A freely- programming interface (API) to control protocol operation. A freely-
available, open source reference implementation of NORM is available available, open source reference implementation of NORM is available
at https://www.nrl.navy.mil/itd/ncs/products/norm, and a documented at https://www.nrl.navy.mil/itd/ncs/products/norm, and a documented
API is provided for this implementation. While a sockets-like API is API is provided for this implementation. While a sockets-like API is
not currently documented, the existing API supports the necessary not currently documented, the existing API supports the necessary
functions for that to be implemented. functions for that to be implemented.
3.11.3. Transport Features 4.10.3. Transport Features
The transport features provided by NORM are: The transport features provided by NORM are:
o unicast or multicast. o unicast or multicast transport.
o stream-oriented delivery in a single stream. o stream-oriented delivery in a single stream.
o object-oriented delivery of discrete data or file items. o object-oriented delivery of discrete data or file items.
o reliable delivery. o reliable delivery.
o unordered unidirectional delivery (of in-memory data or file bulk o unordered unidirectional delivery (of in-memory data or file bulk
content objects). content objects).
skipping to change at page 32, line 32 skipping to change at page 32, line 20
o segmentation. o segmentation.
o data bundling (Nagle's algorithm). o data bundling (Nagle's algorithm).
o flow control (timer-based and/or ack-based). o flow control (timer-based and/or ack-based).
o congestion control. o congestion control.
o packet erasure coding (both proactively and as part of ARQ). o packet erasure coding (both proactively and as part of ARQ).
3.12. Transport Layer Security (TLS) and Datagram TLS (DTLS) as a 4.11. Transport Layer Security (TLS) and Datagram TLS (DTLS) as a
pseudotransport pseudotransport
Transport Layer Security (TLS) and Datagram TLS (DTLS) are IETF Transport Layer Security (TLS) and Datagram TLS (DTLS) are IETF
protocols that provide several security-related features to protocols that provide several security-related features to
applications. TLS is designed to run on top of a reliable streaming applications. TLS is designed to run on top of a reliable streaming
transport protocol (usually TCP), while DTLS is designed to run on transport protocol (usually TCP), while DTLS is designed to run on
top of a best-effort datagram protocol (UDP or DCCP [RFC5238]). At top of a best-effort datagram protocol (UDP or DCCP [RFC5238]). At
the time of writing, the current version of TLS is 1.2; it is defined the time of writing, the current version of TLS is 1.2; which is
in [RFC5246]. DTLS provides nearly identical functionality to defined in [RFC5246]. DTLS provides nearly identical functionality
applications; it is defined in [RFC6347] and its current version is to applications; it is defined in [RFC6347] and its current version
also 1.2. The TLS protocol evolved from the Secure Sockets Layer is also 1.2. The TLS protocol evolved from the Secure Sockets Layer
(SSL) protocols developed in the mid 90s to support protection of (SSL) protocols developed in the mid 90s to support protection of
HTTP traffic. HTTP traffic.
While older versions of TLS and DTLS are still in use, they provide While older versions of TLS and DTLS are still in use, they provide
weaker security guarantees. [RFC7457] outlines important attacks on weaker security guarantees. [RFC7457] outlines important attacks on
TLS and DTLS. [RFC7525] is a Best Current Practices (BCP) document TLS and DTLS. [RFC7525] is a Best Current Practices (BCP) document
that describes secure configurations for TLS and DTLS to counter that describes secure configurations for TLS and DTLS to counter
these attacks. The recommendations are applicable for the vast these attacks. The recommendations are applicable for the vast
majority of use cases. majority of use cases.
[NOTE: The Logjam authors (weakdh.org) give (inconclusive) evidence 4.11.1. Protocol Description
that one of the recommendations of [RFC7525], namely the use of
DHE-1024 as a fallback, may not be sufficient in all cases to counter
an attacker with the resources of a nation-state. It is unclear at
this time if the RFC is going to be updated as a result, or whether
there will be an RFC7525bis.]
3.12.1. Protocol Description
Both TLS and DTLS provide the same security features and can thus be Both TLS and DTLS provide the same security features and can thus be
discussed together. The features they provide are: discussed together. The features they provide are:
o Confidentiality o Confidentiality
o Data integrity o Data integrity
o Peer authentication (optional) o Peer authentication (optional)
o Perfect forward secrecy (optional) o Perfect forward secrecy (optional)
The authentication of the peer entity can be omitted; a common web The authentication of the peer entity can be omitted; a common web
use case is where the server is authenticated and the client is not. use case is where the server is authenticated and the client is not.
TLS also provides a completely anonymous operation mode in which TLS also provides a completely anonymous operation mode in which
neither peer's identity is authenticated. It is important to note neither peer's identity is authenticated. It is important to note
that TLS itself does not specify how a peering entity's identity that TLS itself does not specify how a peering entity's identity
should be interpreted. For example, in the common use case of should be interpreted. For example, in the common use case of
authentication by means of an X.509 certificate, it is the authentication by means of an X.509 certificate, it is the
application's decision whether the certificate of the peering entity application's decision whether the certificate of the peering entity
skipping to change at page 33, line 40 skipping to change at page 33, line 21
should be interpreted. For example, in the common use case of should be interpreted. For example, in the common use case of
authentication by means of an X.509 certificate, it is the authentication by means of an X.509 certificate, it is the
application's decision whether the certificate of the peering entity application's decision whether the certificate of the peering entity
is acceptable for authorization decisions. Perfect forward secrecy, is acceptable for authorization decisions. Perfect forward secrecy,
if enabled and supported by the selected algorithms, ensures that if enabled and supported by the selected algorithms, ensures that
traffic encrypted and captured during a session at time t0 cannot be traffic encrypted and captured during a session at time t0 cannot be
later decrypted at time t1 (t1 > t0), even if the long-term secrets later decrypted at time t1 (t1 > t0), even if the long-term secrets
of the communicating peers are later compromised. of the communicating peers are later compromised.
As DTLS is generally used over an unreliable datagram transport such As DTLS is generally used over an unreliable datagram transport such
as UDP, applications will need to tolerate loss, re-ordered, or as UDP, applications will need to tolerate lost, re-ordered, or
duplicated datagrams. Like TLS, DTLS conveys application data in a duplicated datagrams. Like TLS, DTLS conveys application data in a
sequence of independent records. However, because records are mapped sequence of independent records. However, because records are mapped
to unreliable datagrams, there are several features unique to DTLS to unreliable datagrams, there are several features unique to DTLS
that are not applicable to TLS: that are not applicable to TLS:
o Record replay detection (optional). o Record replay detection (optional).
o Record size negotiation (estimates of PMTU and record size o Record size negotiation (estimates of PMTU and record size
expansion factor). expansion factor).
o Coveyance of IP don't fragment (DF) bit settings by application. o Coveyance of IP don't fragment (DF) bit settings by application.
o An anti-DoS stateless cookie mechanism (optional). o An anti-DoS stateless cookie mechanism (optional).
Generally, DTLS follows the TLS design as closely as possible. To Generally, DTLS follows the TLS design as closely as possible. To
operate over datagrams, DTLS includes a sequence number and limited operate over datagrams, DTLS includes a sequence number and limited
forms of retransmission and fragmentation for its internal forms of retransmission and fragmentation for its internal
operations. The sequence number may be used for detecting replayed operations. The sequence number may be used for detecting replayed
information, according to the windowing procedure described in information, according to the windowing procedure described in
Section 4.1.2.6 of [RFC6347]. Note also that DTLS forbids the use of Section 4.1.2.6 of [RFC6347]. DTLS forbids the use of stream
stream ciphers, which are essentially incompatible when operating on ciphers, which are essentially incompatible when operating on
independent encrypted records. independent encrypted records.
3.12.2. Interface Description 4.11.2. Interface Description
TLS is commonly invoked using an API provided by packages such as TLS is commonly invoked using an API provided by packages such as
OpenSSL, wolfSSL, or GnuTLS. Using such APIs entails the OpenSSL, wolfSSL, or GnuTLS. Using such APIs entails the
manipulation of several important abstractions, which fall into the manipulation of several important abstractions, which fall into the
following categories: long-term keys and algorithms, session state, following categories: long-term keys and algorithms, session state,
and communications/connections. There may also be special APIs and communications/connections. There may also be special APIs
required to deal with time and/or random numbers, both of which are required to deal with time and/or random numbers, both of which are
needed by a variety of encryption algorithms and protocols. needed by a variety of encryption algorithms and protocols.
Considerable care is required in the use of TLS APIs in order to Considerable care is required in the use of TLS APIs to ensure
create a secure application. The programmer should have at least a creation of a secure application. The programmer should have at
basic understanding of encryption and digital signature algorithms least a basic understanding of encryption and digital signature
and their strengths, public key infrastructure (including X.509 algorithms and their strengths, public key infrastructure (including
certificates and certificate revocation), and the sockets API. See X.509 certificates and certificate revocation), and the sockets API.
[RFC7525] and [RFC7457], as mentioned above. See [RFC7525] and [RFC7457], as mentioned above.
As an example, in the case of OpenSSL, the primary abstractions are As an example, in the case of OpenSSL, the primary abstractions are
the library itself and method (protocol), session, context, cipher the library itself and method (protocol), session, context, cipher
and connection. After initializing the library and setting the and connection. After initializing the library and setting the
method, a cipher suite is chosen and used to configure a context method, a cipher suite is chosen and used to configure a context
object. Session objects may then be minted according to the object. Session objects may then be minted according to the
parameters present in a context object and associated with individual parameters present in a context object and associated with individual
connections. Depending on how precisely the programmer wishes to connections. Depending on how precisely the programmer wishes to
select different algorithmic or protocol options, various levels of select different algorithmic or protocol options, various levels of
details may be required. details may be required.
3.12.3. Transport Features 4.11.3. Transport Features
Both TLS and DTLS employ a layered architecture. The lower layer is Both TLS and DTLS employ a layered architecture. The lower layer is
commonly called the record protocol. It is responsible for: commonly called the record protocol. It is responsible for:
o message fragmentation o message fragmentation.
o authentication and integrity via message authentication codes o authentication and integrity via message authentication codes
(MAC) (MAC).
o data encryption o data encryption.
o scheduling transmission using the underlying transport protocol o scheduling transmission using the underlying transport protocol.
DTLS augments the TLS record protocol with: DTLS augments the TLS record protocol with:
o ordering and replay protection, implemented using sequence o ordering and replay protection, implemented using sequence
numbers. numbers.
Several protocols are layered on top of the record protocol. These Several protocols are layered on top of the record protocol. These
include the handshake, alert, and change cipher spec protocols. include the handshake, alert, and change cipher spec protocols.
There is also the data protocol, used to carry application traffic. There is also the data protocol, used to carry application traffic.
The handshake protocol is used to establish cryptographic and The handshake protocol is used to establish cryptographic and
compression parameters when a connection is first set up. In DTLS, compression parameters when a connection is first set up. In DTLS,
this protocol also has a basic fragmentation and retransmission this protocol also has a basic fragmentation and retransmission
capability and a cookie-like mechanism to resist DoS attacks. (TLS capability and a cookie-like mechanism to resist DoS attacks. (TLS
compression is not recommended at present). The alert protocol is compression is not recommended at present). The alert protocol is
used to inform the peer of various conditions, most of which are used to inform the peer of various conditions, most of which are
terminal for the connection. The change cipher spec protocol is used terminal for the connection. The change cipher spec protocol is used
to synchronize changes in cryptographic parameters for each peer. to synchronize changes in cryptographic parameters for each peer.
3.13. Hypertext Transport Protocol (HTTP) over TCP as a pseudotransport The data protocol, when used with an appropriate cipher, provides:
Hypertext Transfer Protocol (HTTP) is an application-level protocol o authentication of one end or both ends of a connection.
widely used on the Internet. Version 1.1 of the protocol is
o confidentiality.
o cryptographic integrity protection.
4.12. Hypertext Transport Protocol (HTTP) over TCP as a pseudotransport
The Hypertext Transfer Protocol (HTTP) is an application-level
protocol widely used on the Internet. Version 1.1 of the protocol is
specified in [RFC7230] [RFC7231] [RFC7232] [RFC7233] [RFC7234] specified in [RFC7230] [RFC7231] [RFC7232] [RFC7233] [RFC7234]
[RFC7235], and version 2 in [RFC7540]. Furthermore, HTTP is used as [RFC7235], and version 2 in [RFC7540]. HTTP is usually transported
a substrate for other application-layer protocols. There are various over TCP using port 80 and 443, although it can be used with other
reasons for this practice listed in [RFC3205]; these include being a transports. When used over TCP it inherits its properties.
well-known and well-understood protocol, reusability of existing
servers and client libraries, easy use of existing security
mechanisms such as HTTP digest authentication [RFC2617] and TLS
[RFC5246], the ability of HTTP to traverse firewalls which makes it
work with a lot of infrastructure, and cases where a application
server often needs to support HTTP anyway.
Depending on application's needs, the use of HTTP as a substrate HTTP is used as a substrate for other application-layer protocols.
There are various reasons for this practice listed in [RFC3205];
these include being a well-known and well-understood protocol,
reusability of existing servers and client libraries, easy use of
existing security mechanisms such as HTTP digest authentication
[RFC2617] and TLS [RFC5246], the ability of HTTP to traverse
firewalls makes it work over many types of infrastructure, and in
cases where a application server often needs to support HTTP anyway.
Depending on application need, the use of HTTP as a substrate
protocol may add complexity and overhead in comparison to a special- protocol may add complexity and overhead in comparison to a special-
purpose protocol (e.g. HTTP headers, suitability of the HTTP purpose protocol (e.g., HTTP headers, suitability of the HTTP
security model etc.). [RFC3205] address this issues and provides security model, etc.). [RFC3205] addresses this issue and provides
some guidelines and concerns about the use of HTTP standard port 80 some guidelines and concerns about the use of HTTP standard port 80
and 443, the use of HTTP URL scheme and interaction with existing and 443, the use of HTTP URL scheme and interaction with existing
firewalls, proxies and NATs. firewalls, proxies and NATs.
Though not strictly bound to TCP, HTTP is almost exclusively run over 4.12.1. Protocol Description
TCP, and therefore inherits its properties when used in this way.
3.13.1. Protocol Description
Hypertext Transfer Protocol (HTTP) is a request/response protocol. A Hypertext Transfer Protocol (HTTP) is a request/response protocol. A
client sends a request containing a request method, URI and protocol client sends a request containing a request method, URI and protocol
version followed by a MIME-like message (see [RFC7231] for the version followed by a MIME-like message (see [RFC7231] for the
differences between an HTTP object and a MIME message), containing differences between an HTTP object and a MIME message), containing
information about the client and request modifiers. The message can information about the client and request modifiers. The message can
contain a message body carrying application data as well. The server contain a message body carrying application data as well. The server
responds with a status or error code followed by a MIME-like message responds with a status or error code followed by a MIME-like message
containing information about the server and information about carried containing information about the server and information about carried
data and it can include a message body. It is possible to specify a data and it can include a message body. It is possible to specify a
data format for the message body using MIME media types [RFC2045]. data format for the message body using MIME media types [RFC2045].
Furthermore, the protocol has numerous additional features; features Furthermore, the protocol has numerous additional features; features
relevant to pseudotransport are described below. relevant to pseudotransport are described below.
Content negotiation, specified in [RFC7231], is a mechanism provided Content negotiation, specified in [RFC7231], is a mechanism provided
by HTTP for selecting a representation on a requested resource. The by HTTP for selecting a representation on a requested resource. The
client and server negotiate acceptable data formats, charsets, data client and server negotiate acceptable data formats, charsets, data
encoding (e.g. data can be transferred compressed, gzip), etc. HTTP encoding (e.g., data can be transferred compressed using gzip), etc.
can accommodate exchange of messages as well as data streaming (using HTTP can accommodate exchange of messages as well as data streaming
chunked transfer encoding [RFC7230]). It is also possible to request (using chunked transfer encoding [RFC7230]). It is also possible to
a part of a resource using range requests specified in [RFC7233]. request a part of a resource using range requests specified in
The protocol provides powerful cache control signalling defined in [RFC7233]. The protocol provides powerful cache control signalling
[RFC7234]. defined in [RFC7234].
HTTP 1.1's and HTTP 2.0's persistent connections can be use to HTTP 1.1's and HTTP 2.0's persistent connections can be use to
perform multiple request-response transactions during the life-time perform multiple request-response transactions during the life-time
of a single HTTP connection. Moreover, HTTP 2.0 connections can of a single HTTP connection. Moreover, HTTP 2.0 connections can
multiplex many request/response pairs in parallel on a single multiplex many request/response pairs in parallel on a single
connection. This reduces connection establishment overhead and the transport connection. This reduces connection establishment overhead
effect of TCP slow-start on each transaction, important for HTTP's and the effect of the transport layer slow-start on each transaction,
primary use case. important in reducing latency for HTTP's primary use case.
It is possible to combine HTTP with security mechanisms, like TLS It is possible to combine HTTP with security mechanisms, like TLS
(denoted by HTTPS), which adds protocol properties provided by such a (denoted by HTTPS), which adds protocol properties provided by such a
mechanism (e.g. authentication, encryption, etc.). TLS's mechanism (e.g., authentication, encryption). The TLS Application-
Application-Layer Protocol Negotiation (ALPN) extension [RFC7301] can Layer Protocol Negotiation (ALPN) extension [RFC7301] can be used for
be used for HTTP version negotiation within TLS handshake which HTTP version negotiation within the TLS handshake, which eliminates
eliminates addition round-trip. Arbitrary cookie strings, included the latency of addition round-trips. Arbitrary cookie strings,
as part of the MIME headers, are often used as bearer tokens in HTTP. included as part of the MIME headers, are often used as bearer tokens
in HTTP.
Application layer protocols using HTTP as substrate may use existing Application layer protocols using HTTP as substrate may use an
method and data formats, or specify new methods and data formats. existing method and data formats, or specify new methods and data
Furthermore some protocols may not fit a request/response paradigm formats. Furthermore some protocols may not fit a request/response
and instead rely on HTTP to send messages (e.g. [RFC6546]). Because paradigm and instead rely on HTTP to send messages (e.g., [RFC6546]).
HTTP is working in many restricted infrastructures, it is also used Because HTTP works in many restricted infrastructures, it is also
to tunnel other application-layer protocols. used to tunnel other application-layer protocols.
3.13.2. Interface Description 4.12.2. Interface Description
There are many HTTP libraries available exposing different APIs. The There are many HTTP libraries available exposing different APIs. The
APIs provide a way to specify a request by providing a URI, a method, APIs provide a way to specify a request by providing a URI, a method,
request modifiers and optionally a request body. For the response, request modifiers and optionally a request body. For the response,
callbacks can be registered that will be invoked when the response is callbacks can be registered that will be invoked when the response is
received. If TLS is used, API expose a registration of callbacks in received. If TLS is used, API expose a registration of callbacks in
case a server requests client authentication and when certificate case a server requests client authentication and when certificate
verification is needed. verification is needed.
World Wide Web Consortium (W3C) standardized the XMLHttpRequest API World Wide Web Consortium (W3C) standardized the XMLHttpRequest API
skipping to change at page 37, line 28 skipping to change at page 37, line 18
response data format can also be JSON, HTML and plain text. response data format can also be JSON, HTML and plain text.
Specifically JavaScript and XMLHttpRequest are a ubiquitous Specifically JavaScript and XMLHttpRequest are a ubiquitous
programming model for websites, and more general applications, where programming model for websites, and more general applications, where
native code is less attractive. native code is less attractive.
Representational State Transfer (REST) [REST] is another example how Representational State Transfer (REST) [REST] is another example how
applications can use HTTP as transport protocol. REST is an applications can use HTTP as transport protocol. REST is an
architecture style for building application on the Internet. It uses architecture style for building application on the Internet. It uses
HTTP as a communication protocol. HTTP as a communication protocol.
3.13.3. Transport features 4.12.3. Transport features
The transport features provided by HTTP, when used as a The transport features provided by HTTP, when used as a
pseudotransport, are: pseudotransport, are:
o unicast. o unicast.
o message and stream-oriented transfer. o message and stream-oriented transfer.
o bi- or unidirectional transmission. o bi- or unidirectional transmission.
skipping to change at page 38, line 9 skipping to change at page 37, line 47
o flow control. o flow control.
HTTPS (HTTP over TLS) additionally provides the following components: HTTPS (HTTP over TLS) additionally provides the following components:
o authentication (of one or both ends of a connection). o authentication (of one or both ends of a connection).
o confidentiality. o confidentiality.
o integrity protection. o integrity protection.
4. Transport Service Features 5. Transport Service Features
[EDITOR'S NOTE: This section is still work-in-progress. This list is The tables below summarize some key features to illustrate the range
probably not complete and/or too detailed.] of functions provided across the IETF-specified transports. Figure 1
considers transports that may be directly layered over the network,
and Figure 2 considers transports layered over another transport
service.
The transport protocol components analyzed in this document which can +---------------+------+------+------+------+------+------+------+
| Feature | TCP | MPTCP| SCTP | UDP | UDP-L|DCCP |ICMP |
+---------------+------+------+------+------+------+------+------+
| Datagram | No | No | Yes | Yes | Yes | Yes | Yes |
+---------------+------+------+------+------+------+------+------+
| Conn. Oriented| Yes | Yes | Yes | No | No | Yes | No |
+---------------+------+------+------+------+------+------+------+
| Reliability | Yes | Yes | Yes | No | No | No | No |
+---------------+------+------+------+------+------+------+------+
| Partial Rel. | No | No | Pos | N/A | N/A | Yes | N/A |
+---------------+------+------+------+------+------+------+------+
| Corupt. Tol | No | No | No | No | Yes | Yes | No |
+---------------+------+------+------+------+------+------+------+
| Cong.Control | Yes | Yes | Yes | No | No | Yes | No |
+---------------+------+------+------+------+------+------+------+
| Endpoint | 1 | >=1 | >=1 | 1 | 1 | 1 | 1 |
+---------------+------+------+------+------+------+------+------+
| Multicast Cap.| No | No | No | Yes | Yes | No | No |
+---------------+------+------+------+------+------+------+------+
Figure 1: Summary comparison: Transport protocols
+---------------+------+------+------+------+------+
| Feature | RTP | FLUTE| NORM |(D)TLS| HTTP |
+---------------+------+------+------+------+------+
| Datagram | Yes | No | Both | Both | No |
+---------------+------+------+------+------+------+
| Conn. Oriented| No | Yes | Yes | Yes | Yes |
+---------------+------+------+------+------+------+
| Reliability | No | Yes | Pos | Pos | Yes |
+---------------+------+------+------+------+------+
| Partial R | Pos | No | Pos | No | No |
+---------------+------+------+------+------+------+
| Corupt. Tol | Poss | No | No | No | No |
+---------------+------+------+------+------+------+
| Cong.Control | Poss | Poss | Poss | N/A | N/A |
+---------------+------+------+------+------+------+
| Endpoint | >=1 | >=1 | >=1 | 1 | 1 |
+---------------+------+------+------+------+------+
| Multicast Cap.| Yes | Yes | Yes | No | No |
+---------------+------+------+------+------+------+
Figure 2: Upper layer transports and frameworks
The transport protocol components analyzed in this document that can
be used as a basis for defining common transport service features, be used as a basis for defining common transport service features,
normalized and separated into categories, are as follows: normalized and separated into categories, are as follows:
o Control Functions o Control Functions
* Addressing * Addressing
+ unicast + unicast (TCP, MPTCP, SCTP, UDP, UDP-Lite, DCCP, TLS, HTTP)
+ multicast, anycast and IPv4 broadcast
+ use of NAPT-compatible port numbers
* Multihoming support + multicast (UDP, UDP-Lite, DCCP, FLUTE/ALC, NORM)
+ multihoming for resilience + IPv4 broadcast (UDP, UDP-Lite, DCCP)
+ multihoming for mobility + anycast (UDP, UDP-Lite, DCCP). Connection-oriented
protocols such as TCP can be and are used with anycast
routing, with the risk that routing changes may cause
connection failure.
- specify handover latency? * Multihoming support
+ multihoming for load-balancing + multihoming for resilience (MPTCP, SCTP)
- specify interleaving delay? + multihoming for mobility (MPTCP, SCTP)
* Multiplexing + multihoming for load-balancing (MPTCP)
+ application to port mapping * Application to port mapping (TCP, MPTCP, SCTP, UDP, UDP-Lite,
DCCP, FLUTE/ALC, NORM, TLS, HTTP)
+ single vs. multiple streaming + with commonly deployed support in NAPT (TCP, MPTCP, UDP,
TLS, HTTP)
o Delivery o Delivery
* reliability * reliability
+ fully reliable delivery + fully reliable delivery (TCP, MPTCP, SCTP, FLUTE/ALC, NORM,
TLS, HTTP)
+ partially reliable delivery + partially reliable delivery (SCTP, NORM)
- packet erasure coding
+ unreliable delivery - using packet erasure coding (NORM, FLUTE, RTP)
- drop notification + unreliable delivery (SCTP, UDP, UDP-Lite, DCCP)
- Integrity protection - with drop notification (SCTP, DCCP)
o checksum for error detection + Integrity protection
o partial payload checksum protection - checksum for error detection (TCP, MPTCP, SCTP, UDP, UDP-
Lite, DCCP, FLUTE/ALC, NORM, TLS, HTTP)
o checksum optional - partial payload checksum protection (UDP-Lite, DCCP)
* ordering - checksum optional (UDP)
+ ordered delivery * ordering
+ unordered delivery + ordered delivery (TCP, MPTCP, SCTP, TLS, HTTP)
- unordered delivery of in-memory data + unordered delivery (SCTP, UDP, UDP-Lite, DCCP, NORM)
* type/framing * type/framing
+ stream-oriented delivery + stream-oriented delivery (TCP, MPTCP, SCTP, TLS)
+ message-oriented delivery
+ object-oriented delivery of discrete data or file items
- object content type negotiation - with multiple streams per association (SCTP)
+ range-based partical object transmission + message-oriented delivery (SCTP, UDP, UDP-Lite, DCCP, DTLS)
+ file bulk content objects + object-oriented delivery of discrete data or file items
(FLUTE/ALC, NORM, HTTP)
o Transmission control o Transmission control
* rate control * flow control (TCP, MPTCP, SCTP, DCCP, TLS, HTTP)
+ timer-based
+ ACK-based
* congestion control
* flow control
* segmentation
* data/message bundling (Nagle's algorithm)
* stream scheduling prioritization
o Security
* authentication of one end of a connection
* authentication of both ends of a connection
* confidentiality
* cryptographic integrity protection
A future revision of this document will define transport service * congestion control (TCP, MPTCP, SCTP, DCCP, FLUTE/ALC, NORM,
features based upon this list. TLS, HTTP)
[EDITOR'S NOTE: this section will drawn from the candidate features * segmentation (TCP, MPTCP, SCTP, FLUTE/ALC, NORM, TLS, HTTP)
provided by protocol components in the previous section - please
discuss on taps@ietf.org list]
4.1. Complete Protocol Feature Matrix * data/message bundling (TCP, MPTCP, SCTP, TLS, HTTP)
[EDITOR'S NOTE: Dave Thaler has signed up as a contributor for this * stream scheduling prioritization (SCTP)
section. Michael Welzl also has a beginning of a matrix which could
be useful here.]
[EDITOR'S NOTE: The below is a strawman proposal below by Gorry o Security (may be used in combination with other transports)
Fairhurst for initial discussion]
The table below summarises protocol mechanisms that have been * authentication of one end of a connection (TLS)
standardised. It does not make an assessment on whether specific
implementations are fully compliant to these specifications.
+-----------------+---------+---------+---------+---------+---------+ * authentication of both ends of a connection (TLS)
| Mechanism | UDP | UDP-L | DCCP | SCTP | TCP |
+-----------------+---------+---------+---------+---------+---------+
| Unicast | Yes | Yes | Yes | Yes | Yes |
| | | | | | |
| Mcast/IPv4Bcast | Yes(2) | Yes | No | No | No |
| | | | | | |
| Port Mux | Yes | Yes | Yes | Yes | Yes |
| | | | | | |
| Mode | Dgram | Dgram | Dgram | Dgram | Stream |
| | | | | | |
| Connected | No | No | Yes | Yes | Yes |
| | | | | | |
| Data bundling | No | No | No | Yes | Yes |
| | | | | | |
| Feature Nego | No | No | Yes | Yes | Yes |
| | | | | | |
| Options | No | No | Support | Support | Support |
| | | | | | |
| Data priority | * | * | * | Yes | No |
| | | | | | |
| Data bundling | No | No | No | Yes | Yes |
| | | | | | |
| Reliability | None | None | None | Select | Full |
| | | | | | |
| Ordered deliv | No | No | No | Stream | Yes |
| | | | | | |
| Corruption Tol. | No | Support | Support | No | No |
| | | | | | |
| Flow Control | No | No | Support | Yes | Yes |
| | | | | | |
| PMTU/PLPMTU | (1) | (1) | Yes | Yes | Yes |
| | | | | | |
| Cong Control | (1) | (1) | Yes | Yes | Yes |
| | | | | | |
| ECN Support | (1) | (1) | Yes | TBD | Yes |
| | | | | | |
| NAT support | Limited | Limited | Support | TBD | Support |
| | | | | | |
| Security | DTLS | DTLS | DTLS | DTLS | TLS, AO |
| | | | | | |
| UDP encaps | N/A | None | Yes | Yes | None |
| | | | | | |
| RTP support | Support | Support | Support | ? | Support |
+-----------------+---------+---------+---------+---------+---------+
Note (1): this feature requires support in an upper layer protocol. * confidentiality (TLS)
Note (2): this feature requires support in an upper layer protocol * cryptographic integrity protection (TLS)
when used with IPv6.
5. IANA Considerations 6. IANA Considerations
This document has no considerations for IANA. This document has no considerations for IANA.
6. Security Considerations 7. Security Considerations
This document surveys existing transport protocols and protocols This document surveys existing transport protocols and protocols
providing transport-like services. Confidentiality, integrity, and providing transport-like services. Confidentiality, integrity, and
authenticity are among the features provided by those services. This authenticity are among the features provided by those services. This
document does not specify any new components or mechanisms for document does not specify any new components or mechanisms for
providing these features. Each RFC listed in this document discusses providing these features. Each RFC listed in this document discusses
the security considerations of the specification it contains. the security considerations of the specification it contains.
7. Contributors 8. Contributors
[Editor's Note: turn this into a real contributors section with In addition to the editors, this document is the work of Brian
addresses once we figure out how to trick the toolchain into doing Adamson, Dragana Damjanovic, Kevin Fall, Simone Ferlin-Oliviera,
so] Ralph Holz, Olivier Mehani, Karen Nielsen, Colin Perkins, Vincent
Roca, and Michael Tuexen.
o Section 3.2 on MPTCP was contributed by Simone Ferlin-Oliviera o Section 4.2 on MPTCP was contributed by Simone Ferlin-Oliviera
(ferlin@simula.no) and Olivier Mehani (ferlin@simula.no) and Olivier Mehani
(olivier.mehani@nicta.com.au) (olivier.mehani@nicta.com.au)
o Section 3.4 on UDP was contributed by Kevin Fall (kfall@kfall.com) o Section 4.4 on UDP was contributed by Kevin Fall (kfall@kfall.com)
o Section 3.3 on SCTP was contributed by Michael Tuexen (tuexen@fh- o Section 4.3 on SCTP was contributed by Michael Tuexen (tuexen@fh-
muenster.de) muenster.de) and Karen Nielsen (karen.nielsen@tieto.com)
o Section 3.10 on FLUTE/ALC was contributed by Vincent Roca o Section 4.8 on RTP contains contributions from Colin Perlins
(csp@csperkins.org)
o Section 4.9 on FLUTE/ALC was contributed by Vincent Roca
(vincent.roca@inria.fr) (vincent.roca@inria.fr)
o Section 3.11 on NORM was contributed by Brian Adamson o Section 4.10 on NORM was contributed by Brian Adamson
(brian.adamson@nrl.navy.mil) (brian.adamson@nrl.navy.mil)
o Section 3.12 on TLS and DTLS was contributed by Ralph Holz o Section 4.11 on TLS and DTLS was contributed by Ralph Holz
(ralph.holz@nicta.com.au) and Olivier Mehani (ralph.holz@nicta.com.au) and Olivier Mehani
(olivier.mehani@nicta.com.au) (olivier.mehani@nicta.com.au)
o Section 3.13 on HTTP was contributed by Dragana Damjanovic o Section 4.12 on HTTP was contributed by Dragana Damjanovic
(ddamjanovic@mozilla.com) (ddamjanovic@mozilla.com)
8. Acknowledgments 9. Acknowledgments
Thanks to Karen Nielsen, Joe Touch, and Michael Welzl for the Thanks to Joe Touch, Michael Welzl, and the TAPS Working Group for
comments, feedback, and discussion. This work is partially supported the comments, feedback, and discussion. This work is partially
by the European Commission under grant agreements FP7-ICT-318627 supported by the European Commission under grant agreements
mPlane and from the Horizon 2020 research and innovation program FP7-ICT-318627 mPlane and from the Horizon 2020 research and
under grant agreement No. 644334 (NEAT); support does not imply innovation program under grant agreement No. 644334 (NEAT); support
endorsement. does not imply endorsement.
9. Informative References 10. Informative References
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
10.17487/RFC0768, August 1980, DOI 10.17487/RFC0768, August 1980,
<http://www.rfc-editor.org/info/rfc768>. <http://www.rfc-editor.org/info/rfc768>.
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981, RFC 792, DOI 10.17487/RFC0792, September 1981,
<http://www.rfc-editor.org/info/rfc792>. <http://www.rfc-editor.org/info/rfc792>.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>. <http://www.rfc-editor.org/info/rfc793>.
[RFC0896] Nagle, J., "Congestion Control in IP/TCP Internetworks", [RFC0896] Nagle, J., "Congestion Control in IP/TCP Internetworks",
RFC 896, DOI 10.17487/RFC0896, January 1984, RFC 896, DOI 10.17487/RFC0896, January 1984,
<http://www.rfc-editor.org/info/rfc896>. <http://www.rfc-editor.org/info/rfc896>.
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, DOI 10.17487/ Communication Layers", STD 3, RFC 1122,
RFC1122, October 1989, DOI 10.17487/RFC1122, October 1989,
<http://www.rfc-editor.org/info/rfc1122>. <http://www.rfc-editor.org/info/rfc1122>.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<http://www.rfc-editor.org/info/rfc1191>. <http://www.rfc-editor.org/info/rfc1191>.
[RFC1716] Almquist, P. and F. Kastenholz, "Towards Requirements for [RFC1716] Almquist, P. and F. Kastenholz, "Towards Requirements for
IP Routers", RFC 1716, DOI 10.17487/RFC1716, November IP Routers", RFC 1716, DOI 10.17487/RFC1716, November
1994, <http://www.rfc-editor.org/info/rfc1716>. 1994, <http://www.rfc-editor.org/info/rfc1716>.
[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery [RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August
1996, <http://www.rfc-editor.org/info/rfc1981>. 1996, <http://www.rfc-editor.org/info/rfc1981>.
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP [RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP
Selective Acknowledgment Options", RFC 2018, DOI 10.17487/ Selective Acknowledgment Options", RFC 2018,
RFC2018, October 1996, DOI 10.17487/RFC2018, October 1996,
<http://www.rfc-editor.org/info/rfc2018>. <http://www.rfc-editor.org/info/rfc2018>.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996, Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
<http://www.rfc-editor.org/info/rfc2045>. <http://www.rfc-editor.org/info/rfc2045>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>. December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461, DOI Discovery for IP Version 6 (IPv6)", RFC 2461,
10.17487/RFC2461, December 1998, DOI 10.17487/RFC2461, December 1998,
<http://www.rfc-editor.org/info/rfc2461>. <http://www.rfc-editor.org/info/rfc2461>.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication", Authentication: Basic and Digest Access Authentication",
RFC 2617, DOI 10.17487/RFC2617, June 1999, RFC 2617, DOI 10.17487/RFC2617, June 1999,
<http://www.rfc-editor.org/info/rfc2617>. <http://www.rfc-editor.org/info/rfc2617>.
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710, DOI Listener Discovery (MLD) for IPv6", RFC 2710,
10.17487/RFC2710, October 1999, DOI 10.17487/RFC2710, October 1999,
<http://www.rfc-editor.org/info/rfc2710>. <http://www.rfc-editor.org/info/rfc2710>.
[RFC2736] Handley, M. and C. Perkins, "Guidelines for Writers of RTP
Payload Format Specifications", BCP 36, RFC 2736,
DOI 10.17487/RFC2736, December 1999,
<http://www.rfc-editor.org/info/rfc2736>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP", RFC of Explicit Congestion Notification (ECN) to IP",
3168, DOI 10.17487/RFC3168, September 2001, RFC 3168, DOI 10.17487/RFC3168, September 2001,
<http://www.rfc-editor.org/info/rfc3168>. <http://www.rfc-editor.org/info/rfc3168>.
[RFC3205] Moore, K., "On the use of HTTP as a Substrate", BCP 56, [RFC3205] Moore, K., "On the use of HTTP as a Substrate", BCP 56,
RFC 3205, DOI 10.17487/RFC3205, February 2002, RFC 3205, DOI 10.17487/RFC3205, February 2002,
<http://www.rfc-editor.org/info/rfc3205>. <http://www.rfc-editor.org/info/rfc3205>.
[RFC3436] Jungmaier, A., Rescorla, E., and M. Tuexen, "Transport [RFC3436] Jungmaier, A., Rescorla, E., and M. Tuexen, "Transport
Layer Security over Stream Control Transmission Protocol", Layer Security over Stream Control Transmission Protocol",
RFC 3436, DOI 10.17487/RFC3436, December 2002, RFC 3436, DOI 10.17487/RFC3436, December 2002,
<http://www.rfc-editor.org/info/rfc3436>. <http://www.rfc-editor.org/info/rfc3436>.
skipping to change at page 45, line 11 skipping to change at page 44, line 16
M., and J. Crowcroft, "Forward Error Correction (FEC) M., and J. Crowcroft, "Forward Error Correction (FEC)
Building Block", RFC 3452, DOI 10.17487/RFC3452, December Building Block", RFC 3452, DOI 10.17487/RFC3452, December
2002, <http://www.rfc-editor.org/info/rfc3452>. 2002, <http://www.rfc-editor.org/info/rfc3452>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>. July 2003, <http://www.rfc-editor.org/info/rfc3550>.
[RFC3738] Luby, M. and V. Goyal, "Wave and Equation Based Rate [RFC3738] Luby, M. and V. Goyal, "Wave and Equation Based Rate
Control (WEBRC) Building Block", RFC 3738, DOI 10.17487/ Control (WEBRC) Building Block", RFC 3738,
RFC3738, April 2004, DOI 10.17487/RFC3738, April 2004,
<http://www.rfc-editor.org/info/rfc3738>. <http://www.rfc-editor.org/info/rfc3738>.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP) Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758, DOI 10.17487/ Partial Reliability Extension", RFC 3758,
RFC3758, May 2004, DOI 10.17487/RFC3758, May 2004,
<http://www.rfc-editor.org/info/rfc3758>. <http://www.rfc-editor.org/info/rfc3758>.
[RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., Ed., [RFC3828] Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., Ed.,
and G. Fairhurst, Ed., "The Lightweight User Datagram and G. Fairhurst, Ed., "The Lightweight User Datagram
Protocol (UDP-Lite)", RFC 3828, DOI 10.17487/RFC3828, July Protocol (UDP-Lite)", RFC 3828, DOI 10.17487/RFC3828, July
2004, <http://www.rfc-editor.org/info/rfc3828>. 2004, <http://www.rfc-editor.org/info/rfc3828>.
[RFC3926] Paila, T., Luby, M., Lehtonen, R., Roca, V., and R. Walsh, [RFC3926] Paila, T., Luby, M., Lehtonen, R., Roca, V., and R. Walsh,
"FLUTE - File Delivery over Unidirectional Transport", RFC "FLUTE - File Delivery over Unidirectional Transport",
3926, DOI 10.17487/RFC3926, October 2004, RFC 3926, DOI 10.17487/RFC3926, October 2004,
<http://www.rfc-editor.org/info/rfc3926>. <http://www.rfc-editor.org/info/rfc3926>.
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971, DOI "SEcure Neighbor Discovery (SEND)", RFC 3971,
10.17487/RFC3971, March 2005, DOI 10.17487/RFC3971, March 2005,
<http://www.rfc-editor.org/info/rfc3971>. <http://www.rfc-editor.org/info/rfc3971>.
[RFC4324] Royer, D., Babics, G., and S. Mansour, "Calendar Access [RFC4324] Royer, D., Babics, G., and S. Mansour, "Calendar Access
Protocol (CAP)", RFC 4324, DOI 10.17487/RFC4324, December Protocol (CAP)", RFC 4324, DOI 10.17487/RFC4324, December
2005, <http://www.rfc-editor.org/info/rfc4324>. 2005, <http://www.rfc-editor.org/info/rfc4324>.
[RFC4336] Floyd, S., Handley, M., and E. Kohler, "Problem Statement [RFC4336] Floyd, S., Handley, M., and E. Kohler, "Problem Statement
for the Datagram Congestion Control Protocol (DCCP)", RFC for the Datagram Congestion Control Protocol (DCCP)",
4336, DOI 10.17487/RFC4336, March 2006, RFC 4336, DOI 10.17487/RFC4336, March 2006,
<http://www.rfc-editor.org/info/rfc4336>. <http://www.rfc-editor.org/info/rfc4336>.
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram [RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram
Congestion Control Protocol (DCCP)", RFC 4340, DOI Congestion Control Protocol (DCCP)", RFC 4340,
10.17487/RFC4340, March 2006, DOI 10.17487/RFC4340, March 2006,
<http://www.rfc-editor.org/info/rfc4340>. <http://www.rfc-editor.org/info/rfc4340>.
[RFC4341] Floyd, S. and E. Kohler, "Profile for Datagram Congestion [RFC4341] Floyd, S. and E. Kohler, "Profile for Datagram Congestion
Control Protocol (DCCP) Congestion Control ID 2: TCP-like Control Protocol (DCCP) Congestion Control ID 2: TCP-like
Congestion Control", RFC 4341, DOI 10.17487/RFC4341, March Congestion Control", RFC 4341, DOI 10.17487/RFC4341, March
2006, <http://www.rfc-editor.org/info/rfc4341>. 2006, <http://www.rfc-editor.org/info/rfc4341>.
[RFC4342] Floyd, S., Kohler, E., and J. Padhye, "Profile for [RFC4342] Floyd, S., Kohler, E., and J. Padhye, "Profile for
Datagram Congestion Control Protocol (DCCP) Congestion Datagram Congestion Control Protocol (DCCP) Congestion
Control ID 3: TCP-Friendly Rate Control (TFRC)", RFC 4342, Control ID 3: TCP-Friendly Rate Control (TFRC)", RFC 4342,
DOI 10.17487/RFC4342, March 2006, DOI 10.17487/RFC4342, March 2006,
<http://www.rfc-editor.org/info/rfc4342>. <http://www.rfc-editor.org/info/rfc4342>.
[RFC4433] Kulkarni, M., Patel, A., and K. Leung, "Mobile IPv4 [RFC4433] Kulkarni, M., Patel, A., and K. Leung, "Mobile IPv4
Dynamic Home Agent (HA) Assignment", RFC 4433, DOI Dynamic Home Agent (HA) Assignment", RFC 4433,
10.17487/RFC4433, March 2006, DOI 10.17487/RFC4433, March 2006,
<http://www.rfc-editor.org/info/rfc4433>. <http://www.rfc-editor.org/info/rfc4433>.
[RFC4614] Duke, M., Braden, R., Eddy, W., and E. Blanton, "A Roadmap [RFC4614] Duke, M., Braden, R., Eddy, W., and E. Blanton, "A Roadmap
for Transmission Control Protocol (TCP) Specification for Transmission Control Protocol (TCP) Specification
Documents", RFC 4614, DOI 10.17487/RFC4614, September Documents", RFC 4614, DOI 10.17487/RFC4614, September
2006, <http://www.rfc-editor.org/info/rfc4614>. 2006, <http://www.rfc-editor.org/info/rfc4614>.
[RFC4654] Widmer, J. and M. Handley, "TCP-Friendly Multicast [RFC4654] Widmer, J. and M. Handley, "TCP-Friendly Multicast
Congestion Control (TFMCC): Protocol Specification", RFC Congestion Control (TFMCC): Protocol Specification",
4654, DOI 10.17487/RFC4654, August 2006, RFC 4654, DOI 10.17487/RFC4654, August 2006,
<http://www.rfc-editor.org/info/rfc4654>. <http://www.rfc-editor.org/info/rfc4654>.
[RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and [RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and
Parameter for the Stream Control Transmission Protocol Parameter for the Stream Control Transmission Protocol
(SCTP)", RFC 4820, DOI 10.17487/RFC4820, March 2007, (SCTP)", RFC 4820, DOI 10.17487/RFC4820, March 2007,
<http://www.rfc-editor.org/info/rfc4820>. <http://www.rfc-editor.org/info/rfc4820>.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<http://www.rfc-editor.org/info/rfc4821>. <http://www.rfc-editor.org/info/rfc4821>.
[RFC4828] Floyd, S. and E. Kohler, "TCP Friendly Rate Control
(TFRC): The Small-Packet (SP) Variant", RFC 4828,
DOI 10.17487/RFC4828, April 2007,
<http://www.rfc-editor.org/info/rfc4828>.
[RFC4895] Tuexen, M., Stewart, R., Lei, P., and E. Rescorla, [RFC4895] Tuexen, M., Stewart, R., Lei, P., and E. Rescorla,
"Authenticated Chunks for the Stream Control Transmission "Authenticated Chunks for the Stream Control Transmission
Protocol (SCTP)", RFC 4895, DOI 10.17487/RFC4895, August Protocol (SCTP)", RFC 4895, DOI 10.17487/RFC4895, August
2007, <http://www.rfc-editor.org/info/rfc4895>. 2007, <http://www.rfc-editor.org/info/rfc4895>.
[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, DOI 10.17487/RFC4960, September 2007, RFC 4960, DOI 10.17487/RFC4960, September 2007,
<http://www.rfc-editor.org/info/rfc4960>. <http://www.rfc-editor.org/info/rfc4960>.
[RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M. [RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
Kozuka, "Stream Control Transmission Protocol (SCTP) Kozuka, "Stream Control Transmission Protocol (SCTP)
Dynamic Address Reconfiguration", RFC 5061, DOI 10.17487/ Dynamic Address Reconfiguration", RFC 5061,
RFC5061, September 2007, DOI 10.17487/RFC5061, September 2007,
<http://www.rfc-editor.org/info/rfc5061>. <http://www.rfc-editor.org/info/rfc5061>.
[RFC5097] Renker, G. and G. Fairhurst, "MIB for the UDP-Lite [RFC5097] Renker, G. and G. Fairhurst, "MIB for the UDP-Lite
protocol", RFC 5097, DOI 10.17487/RFC5097, January 2008, protocol", RFC 5097, DOI 10.17487/RFC5097, January 2008,
<http://www.rfc-editor.org/info/rfc5097>. <http://www.rfc-editor.org/info/rfc5097>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/ (TLS) Protocol Version 1.2", RFC 5246,
RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>. <http://www.rfc-editor.org/info/rfc5246>.
[RFC5238] Phelan, T., "Datagram Transport Layer Security (DTLS) over [RFC5238] Phelan, T., "Datagram Transport Layer Security (DTLS) over
the Datagram Congestion Control Protocol (DCCP)", RFC the Datagram Congestion Control Protocol (DCCP)",
5238, DOI 10.17487/RFC5238, May 2008, RFC 5238, DOI 10.17487/RFC5238, May 2008,
<http://www.rfc-editor.org/info/rfc5238>. <http://www.rfc-editor.org/info/rfc5238>.
[RFC5404] Westerlund, M. and I. Johansson, "RTP Payload Format for [RFC5348] Floyd, S., Handley, M., Padhye, J., and J. Widmer, "TCP
G.719", RFC 5404, DOI 10.17487/RFC5404, January 2009, Friendly Rate Control (TFRC): Protocol Specification",
<http://www.rfc-editor.org/info/rfc5404>. RFC 5348, DOI 10.17487/RFC5348, September 2008,
<http://www.rfc-editor.org/info/rfc5348>.
[RFC5461] Gont, F., "TCP's Reaction to Soft Errors", RFC 5461, DOI [RFC5461] Gont, F., "TCP's Reaction to Soft Errors", RFC 5461,
10.17487/RFC5461, February 2009, DOI 10.17487/RFC5461, February 2009,
<http://www.rfc-editor.org/info/rfc5461>. <http://www.rfc-editor.org/info/rfc5461>.
[RFC5595] Fairhurst, G., "The Datagram Congestion Control Protocol [RFC5595] Fairhurst, G., "The Datagram Congestion Control Protocol
(DCCP) Service Codes", RFC 5595, DOI 10.17487/RFC5595, (DCCP) Service Codes", RFC 5595, DOI 10.17487/RFC5595,
September 2009, <http://www.rfc-editor.org/info/rfc5595>. September 2009, <http://www.rfc-editor.org/info/rfc5595>.
[RFC5596] Fairhurst, G., "Datagram Congestion Control Protocol [RFC5596] Fairhurst, G., "Datagram Congestion Control Protocol
(DCCP) Simultaneous-Open Technique to Facilitate NAT/ (DCCP) Simultaneous-Open Technique to Facilitate NAT/
Middlebox Traversal", RFC 5596, DOI 10.17487/RFC5596, Middlebox Traversal", RFC 5596, DOI 10.17487/RFC5596,
September 2009, <http://www.rfc-editor.org/info/rfc5596>. September 2009, <http://www.rfc-editor.org/info/rfc5596>.
[RFC5622] Floyd, S. and E. Kohler, "Profile for Datagram Congestion
Control Protocol (DCCP) Congestion ID 4: TCP-Friendly Rate
Control for Small Packets (TFRC-SP)", RFC 5622,
DOI 10.17487/RFC5622, August 2009,
<http://www.rfc-editor.org/info/rfc5622>.
[RFC5651] Luby, M., Watson, M., and L. Vicisano, "Layered Coding [RFC5651] Luby, M., Watson, M., and L. Vicisano, "Layered Coding
Transport (LCT) Building Block", RFC 5651, DOI 10.17487/ Transport (LCT) Building Block", RFC 5651,
RFC5651, October 2009, DOI 10.17487/RFC5651, October 2009,
<http://www.rfc-editor.org/info/rfc5651>. <http://www.rfc-editor.org/info/rfc5651>.
[RFC5662] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1
External Data Representation Standard (XDR) Description",
RFC 5662, DOI 10.17487/RFC5662, January 2010,
<http://www.rfc-editor.org/info/rfc5662>.
[RFC5672] Crocker, D., Ed., "RFC 4871 DomainKeys Identified Mail [RFC5672] Crocker, D., Ed., "RFC 4871 DomainKeys Identified Mail
(DKIM) Signatures -- Update", RFC 5672, DOI 10.17487/ (DKIM) Signatures -- Update", RFC 5672,
RFC5672, August 2009, DOI 10.17487/RFC5672, August 2009,
<http://www.rfc-editor.org/info/rfc5672>. <http://www.rfc-editor.org/info/rfc5672>.
[RFC5740] Adamson, B., Bormann, C., Handley, M., and J. Macker, [RFC5740] Adamson, B., Bormann, C., Handley, M., and J. Macker,
"NACK-Oriented Reliable Multicast (NORM) Transport "NACK-Oriented Reliable Multicast (NORM) Transport
Protocol", RFC 5740, DOI 10.17487/RFC5740, November 2009, Protocol", RFC 5740, DOI 10.17487/RFC5740, November 2009,
<http://www.rfc-editor.org/info/rfc5740>. <http://www.rfc-editor.org/info/rfc5740>.
[RFC5775] Luby, M., Watson, M., and L. Vicisano, "Asynchronous [RFC5775] Luby, M., Watson, M., and L. Vicisano, "Asynchronous
Layered Coding (ALC) Protocol Instantiation", RFC 5775, Layered Coding (ALC) Protocol Instantiation", RFC 5775,
DOI 10.17487/RFC5775, April 2010, DOI 10.17487/RFC5775, April 2010,
<http://www.rfc-editor.org/info/rfc5775>. <http://www.rfc-editor.org/info/rfc5775>.
[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion [RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
Control", RFC 5681, DOI 10.17487/RFC5681, September 2009, Control", RFC 5681, DOI 10.17487/RFC5681, September 2009,
<http://www.rfc-editor.org/info/rfc5681>. <http://www.rfc-editor.org/info/rfc5681>.
[RFC6056] Larsen, M. and F. Gont, "Recommendations for Transport- [RFC6056] Larsen, M. and F. Gont, "Recommendations for Transport-
Protocol Port Randomization", BCP 156, RFC 6056, DOI Protocol Port Randomization", BCP 156, RFC 6056,
10.17487/RFC6056, January 2011, DOI 10.17487/RFC6056, January 2011,
<http://www.rfc-editor.org/info/rfc6056>. <http://www.rfc-editor.org/info/rfc6056>.
[RFC6083] Tuexen, M., Seggelmann, R., and E. Rescorla, "Datagram [RFC6083] Tuexen, M., Seggelmann, R., and E. Rescorla, "Datagram
Transport Layer Security (DTLS) for Stream Control Transport Layer Security (DTLS) for Stream Control
Transmission Protocol (SCTP)", RFC 6083, DOI 10.17487/ Transmission Protocol (SCTP)", RFC 6083,
RFC6083, January 2011, DOI 10.17487/RFC6083, January 2011,
<http://www.rfc-editor.org/info/rfc6083>. <http://www.rfc-editor.org/info/rfc6083>.
[RFC6093] Gont, F. and A. Yourtchenko, "On the Implementation of the [RFC6093] Gont, F. and A. Yourtchenko, "On the Implementation of the
TCP Urgent Mechanism", RFC 6093, DOI 10.17487/RFC6093, TCP Urgent Mechanism", RFC 6093, DOI 10.17487/RFC6093,
January 2011, <http://www.rfc-editor.org/info/rfc6093>. January 2011, <http://www.rfc-editor.org/info/rfc6093>.
[RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control [RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control
Transmission Protocol (SCTP) Stream Reconfiguration", RFC Transmission Protocol (SCTP) Stream Reconfiguration",
6525, DOI 10.17487/RFC6525, February 2012, RFC 6525, DOI 10.17487/RFC6525, February 2012,
<http://www.rfc-editor.org/info/rfc6525>. <http://www.rfc-editor.org/info/rfc6525>.
[RFC6546] Trammell, B., "Transport of Real-time Inter-network [RFC6546] Trammell, B., "Transport of Real-time Inter-network
Defense (RID) Messages over HTTP/TLS", RFC 6546, DOI Defense (RID) Messages over HTTP/TLS", RFC 6546,
10.17487/RFC6546, April 2012, DOI 10.17487/RFC6546, April 2012,
<http://www.rfc-editor.org/info/rfc6546>. <http://www.rfc-editor.org/info/rfc6546>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <http://www.rfc-editor.org/info/rfc6347>. January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC6356] Raiciu, C., Handley, M., and D. Wischik, "Coupled [RFC6356] Raiciu, C., Handley, M., and D. Wischik, "Coupled
Congestion Control for Multipath Transport Protocols", RFC Congestion Control for Multipath Transport Protocols",
6356, DOI 10.17487/RFC6356, October 2011, RFC 6356, DOI 10.17487/RFC6356, October 2011,
<http://www.rfc-editor.org/info/rfc6356>. <http://www.rfc-editor.org/info/rfc6356>.
[RFC6363] Watson, M., Begen, A., and V. Roca, "Forward Error [RFC6363] Watson, M., Begen, A., and V. Roca, "Forward Error
Correction (FEC) Framework", RFC 6363, DOI 10.17487/ Correction (FEC) Framework", RFC 6363,
RFC6363, October 2011, DOI 10.17487/RFC6363, October 2011,
<http://www.rfc-editor.org/info/rfc6363>. <http://www.rfc-editor.org/info/rfc6363>.
[RFC6455] Fette, I. and A. Melnikov, "The WebSocket Protocol", RFC
6455, DOI 10.17487/RFC6455, December 2011,
<http://www.rfc-editor.org/info/rfc6455>.
[RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V. [RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V.
Yasevich, "Sockets API Extensions for the Stream Control Yasevich, "Sockets API Extensions for the Stream Control
Transmission Protocol (SCTP)", RFC 6458, DOI 10.17487/ Transmission Protocol (SCTP)", RFC 6458,
RFC6458, December 2011, DOI 10.17487/RFC6458, December 2011,
<http://www.rfc-editor.org/info/rfc6458>. <http://www.rfc-editor.org/info/rfc6458>.
[RFC6584] Roca, V., "Simple Authentication Schemes for the [RFC6584] Roca, V., "Simple Authentication Schemes for the
Asynchronous Layered Coding (ALC) and NACK-Oriented Asynchronous Layered Coding (ALC) and NACK-Oriented
Reliable Multicast (NORM) Protocols", RFC 6584, DOI Reliable Multicast (NORM) Protocols", RFC 6584,
10.17487/RFC6584, April 2012, DOI 10.17487/RFC6584, April 2012,
<http://www.rfc-editor.org/info/rfc6584>. <http://www.rfc-editor.org/info/rfc6584>.
[RFC6726] Paila, T., Walsh, R., Luby, M., Roca, V., and R. Lehtonen, [RFC6726] Paila, T., Walsh, R., Luby, M., Roca, V., and R. Lehtonen,
"FLUTE - File Delivery over Unidirectional Transport", RFC "FLUTE - File Delivery over Unidirectional Transport",
6726, DOI 10.17487/RFC6726, November 2012, RFC 6726, DOI 10.17487/RFC6726, November 2012,
<http://www.rfc-editor.org/info/rfc6726>. <http://www.rfc-editor.org/info/rfc6726>.
[RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A
Datagram Congestion Control Protocol UDP Encapsulation for Datagram Congestion Control Protocol UDP Encapsulation for
NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November
2012, <http://www.rfc-editor.org/info/rfc6773>. 2012, <http://www.rfc-editor.org/info/rfc6773>.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple "TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<http://www.rfc-editor.org/info/rfc6824>. <http://www.rfc-editor.org/info/rfc6824>.
[RFC6897] Scharf, M. and A. Ford, "Multipath TCP (MPTCP) Application [RFC6897] Scharf, M. and A. Ford, "Multipath TCP (MPTCP) Application
Interface Considerations", RFC 6897, DOI 10.17487/RFC6897, Interface Considerations", RFC 6897, DOI 10.17487/RFC6897,
March 2013, <http://www.rfc-editor.org/info/rfc6897>. March 2013, <http://www.rfc-editor.org/info/rfc6897>.
[RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and [RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and
UDP Checksums for Tunneled Packets", RFC 6935, DOI UDP Checksums for Tunneled Packets", RFC 6935,
10.17487/RFC6935, April 2013, DOI 10.17487/RFC6935, April 2013,
<http://www.rfc-editor.org/info/rfc6935>. <http://www.rfc-editor.org/info/rfc6935>.
[RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement
for the Use of IPv6 UDP Datagrams with Zero Checksums", for the Use of IPv6 UDP Datagrams with Zero Checksums",
RFC 6936, DOI 10.17487/RFC6936, April 2013, RFC 6936, DOI 10.17487/RFC6936, April 2013,
<http://www.rfc-editor.org/info/rfc6936>. <http://www.rfc-editor.org/info/rfc6936>.
[RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream [RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream
Control Transmission Protocol (SCTP) Packets for End-Host Control Transmission Protocol (SCTP) Packets for End-Host
to End-Host Communication", RFC 6951, DOI 10.17487/ to End-Host Communication", RFC 6951,
RFC6951, May 2013, DOI 10.17487/RFC6951, May 2013,
<http://www.rfc-editor.org/info/rfc6951>. <http://www.rfc-editor.org/info/rfc6951>.
[RFC7053] Tuexen, M., Ruengeler, I., and R. Stewart, "SACK- [RFC7053] Tuexen, M., Ruengeler, I., and R. Stewart, "SACK-
IMMEDIATELY Extension for the Stream Control Transmission IMMEDIATELY Extension for the Stream Control Transmission
Protocol", RFC 7053, DOI 10.17487/RFC7053, November 2013, Protocol", RFC 7053, DOI 10.17487/RFC7053, November 2013,
<http://www.rfc-editor.org/info/rfc7053>. <http://www.rfc-editor.org/info/rfc7053>.
[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
Framework: Why RTP Does Not Mandate a Single Media
Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
2014, <http://www.rfc-editor.org/info/rfc7202>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", RFC Protocol (HTTP/1.1): Message Syntax and Routing",
7230, DOI 10.17487/RFC7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>. <http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
10.17487/RFC7231, June 2014, DOI 10.17487/RFC7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>. <http://www.rfc-editor.org/info/rfc7231>.
[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests", RFC 7232, DOI Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
10.17487/RFC7232, June 2014, DOI 10.17487/RFC7232, June 2014,
<http://www.rfc-editor.org/info/rfc7232>. <http://www.rfc-editor.org/info/rfc7232>.
[RFC7233] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed., [RFC7233] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed.,
"Hypertext Transfer Protocol (HTTP/1.1): Range Requests", "Hypertext Transfer Protocol (HTTP/1.1): Range Requests",
RFC 7233, DOI 10.17487/RFC7233, June 2014, RFC 7233, DOI 10.17487/RFC7233, June 2014,
<http://www.rfc-editor.org/info/rfc7233>. <http://www.rfc-editor.org/info/rfc7233>.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
RFC 7234, DOI 10.17487/RFC7234, June 2014, RFC 7234, DOI 10.17487/RFC7234, June 2014,
<http://www.rfc-editor.org/info/rfc7234>. <http://www.rfc-editor.org/info/rfc7234>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235, DOI Protocol (HTTP/1.1): Authentication", RFC 7235,
10.17487/RFC7235, June 2014, DOI 10.17487/RFC7235, June 2014,
<http://www.rfc-editor.org/info/rfc7235>. <http://www.rfc-editor.org/info/rfc7235>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <http://www.rfc-editor.org/info/rfc7301>. July 2014, <http://www.rfc-editor.org/info/rfc7301>.
[RFC7323] Borman, D., Braden, B., Jacobson, V., and R. [RFC7323] Borman, D., Braden, B., Jacobson, V., and R.
Scheffenegger, Ed., "TCP Extensions for High Performance", Scheffenegger, Ed., "TCP Extensions for High Performance",
RFC 7323, DOI 10.17487/RFC7323, September 2014, RFC 7323, DOI 10.17487/RFC7323, September 2014,
<http://www.rfc-editor.org/info/rfc7323>. <http://www.rfc-editor.org/info/rfc7323>.
[RFC7457] Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing [RFC7457] Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
Known Attacks on Transport Layer Security (TLS) and Known Attacks on Transport Layer Security (TLS) and
Datagram TLS (DTLS)", RFC 7457, DOI 10.17487/RFC7457, Datagram TLS (DTLS)", RFC 7457, DOI 10.17487/RFC7457,
February 2015, <http://www.rfc-editor.org/info/rfc7457>. February 2015, <http://www.rfc-editor.org/info/rfc7457>.
[RFC7496] Tuexen, M., Seggelmann, R., Stewart, R., and S. Loreto, [RFC7496] Tuexen, M., Seggelmann, R., Stewart, R., and S. Loreto,
"Additional Policies for the Partially Reliable Stream "Additional Policies for the Partially Reliable Stream
Control Transmission Protocol Extension", RFC 7496, DOI Control Transmission Protocol Extension", RFC 7496,
10.17487/RFC7496, April 2015, DOI 10.17487/RFC7496, April 2015,
<http://www.rfc-editor.org/info/rfc7496>. <http://www.rfc-editor.org/info/rfc7496>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer "Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <http://www.rfc-editor.org/info/rfc7525>. 2015, <http://www.rfc-editor.org/info/rfc7525>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>. <http://www.rfc-editor.org/info/rfc7540>.
[I-D.ietf-tsvwg-rfc5405bis] [I-D.ietf-tsvwg-rfc5405bis]
Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", draft-ietf-tsvwg-rfc5405bis-05 (work in Guidelines", draft-ietf-tsvwg-rfc5405bis-07 (work in
progress), August 2015. progress), November 2015.
[I-D.ietf-aqm-ecn-benefits] [I-D.ietf-aqm-ecn-benefits]
Fairhurst, G. and M. Welzl, "The Benefits of using Fairhurst, G. and M. Welzl, "The Benefits of using
Explicit Congestion Notification (ECN)", draft-ietf-aqm- Explicit Congestion Notification (ECN)", draft-ietf-aqm-
ecn-benefits-06 (work in progress), July 2015. ecn-benefits-07 (work in progress), November 2015.
[I-D.ietf-tsvwg-sctp-dtls-encaps] [I-D.ietf-tsvwg-sctp-dtls-encaps]
Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS
Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp- Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp-
dtls-encaps-09 (work in progress), January 2015. dtls-encaps-09 (work in progress), January 2015.
[I-D.ietf-tsvwg-sctp-ndata] [I-D.ietf-tsvwg-sctp-ndata]
Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann, Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann,
"Stream Schedulers and User Message Interleaving for the "Stream Schedulers and User Message Interleaving for the
Stream Control Transmission Protocol", draft-ietf-tsvwg- Stream Control Transmission Protocol", draft-ietf-tsvwg-
sctp-ndata-04 (work in progress), July 2015. sctp-ndata-04 (work in progress), July 2015.
[I-D.ietf-tsvwg-sctp-failover]
Nishida, Y., Natarajan, P., Caro, A., Amer, P., and K.
Nielsen, "SCTP-PF: Quick Failover Algorithm in SCTP",
draft-ietf-tsvwg-sctp-failover-13 (work in progress),
September 2015.
[I-D.ietf-tsvwg-natsupp] [I-D.ietf-tsvwg-natsupp]
Stewart, R., Tuexen, M., and I. Ruengeler, "Stream Control Stewart, R., Tuexen, M., and I. Ruengeler, "Stream Control
Transmission Protocol (SCTP) Network Address Translation Transmission Protocol (SCTP) Network Address Translation
Support", draft-ietf-tsvwg-natsupp-08 (work in progress), Support", draft-ietf-tsvwg-natsupp-08 (work in progress),
July 2015. July 2015.
[XHR] van Kesteren, A., Aubourg, J., Song, J., and H. Steen, [XHR] van Kesteren, A., Aubourg, J., Song, J., and H. Steen,
"XMLHttpRequest working draft "XMLHttpRequest working draft
(http://www.w3.org/TR/XMLHttpRequest/)", 2000. (http://www.w3.org/TR/XMLHttpRequest/)", 2000.
skipping to change at page 52, line 38 skipping to change at page 52, line 13
Chapter 5: Representational State Transfer", 2000. Chapter 5: Representational State Transfer", 2000.
[POSIX] 1-2008, IEEE., "IEEE Standard for Information Technology [POSIX] 1-2008, IEEE., "IEEE Standard for Information Technology
-- Portable Operating System Interface (POSIX) Base -- Portable Operating System Interface (POSIX) Base
Specifications, Issue 7", n.d.. Specifications, Issue 7", n.d..
[MBMS] 3GPP TSG WS S4, ., "3GPP TS 26.346: Multimedia Broadcast/ [MBMS] 3GPP TSG WS S4, ., "3GPP TS 26.346: Multimedia Broadcast/
Multicast Service (MBMS); Protocols and codecs, release 13 Multicast Service (MBMS); Protocols and codecs, release 13
(http://www.3gpp.org/DynaReport/26346.htm).", 2015. (http://www.3gpp.org/DynaReport/26346.htm).", 2015.
[ClarkArch]
Clark, D. and D. Tennenhouse, "Architectural
Considerations for a New Generation of Protocols (Proc.
ACM SIGCOMM)", 1990.
Authors' Addresses Authors' Addresses
Godred Fairhurst (editor) Godred Fairhurst (editor)
University of Aberdeen University of Aberdeen
School of Engineering, Fraser Noble Building School of Engineering, Fraser Noble Building
Aberdeen AB24 3UE Aberdeen AB24 3UE
Email: gorry@erg.abdn.ac.uk Email: gorry@erg.abdn.ac.uk
Brian Trammell (editor) Brian Trammell (editor)
ETH Zurich ETH Zurich
Gloriastrasse 35 Gloriastrasse 35
8092 Zurich 8092 Zurich
Switzerland Switzerland
Email: ietf@trammell.ch Email: ietf@trammell.ch
Mirja Kuehlewind (editor) Mirja Kuehlewind (editor)
ETH Zurich ETH Zurich
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