draft-ietf-issll-diffserv-rsvp-03.txt   draft-ietf-issll-diffserv-rsvp-04.txt 
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R. Yavatkar, Intel R. Yavatkar, Intel
P. Ford, Microsoft P. Ford, Microsoft
F. Baker, Cisco F. Baker, Cisco
L. Zhang, UCLA L. Zhang, UCLA
M. Speer, Sun Microsystems M. Speer, Sun Microsystems
R. Braden, ISI R. Braden, ISI
B. Davie, Cisco B. Davie, Cisco
John Wroclawski, MIT LCS John Wroclawski, MIT LCS
E. Felstaine, Allot Communications E. Felstaine, Allot Communications
Internet Draft Internet Draft
Expires: March, 2000 Expires: September, 2000
Document: draft-ietf-issll-diffserv-rsvp-03.txt September, 1999 Document: draft-ietf-issll-diffserv-rsvp-04.txt March, 2000
A Framework For Integrated Services Operation Over Diffserv Networks A Framework For Integrated Services Operation Over Diffserv Networks
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are all provisions of Section 10 of RFC2026. Internet-Drafts are
Working documents of the Internet Engineering Task Force (IETF), its Working documents of the Internet Engineering Task Force (IETF), its
areas, and its working groups. Note that other groups may also areas, and its working groups. Note that other groups may also
distribute working documents as Internet-Drafts. distribute working documents as Internet-Drafts.
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reference material or to cite them other than as "work in progress." reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved. Copyright (C) The Internet Society (2000). All Rights Reserved.
1. Abstract 1. Abstract
The Integrated Services architecture provides a means for the The Integrated Services architecture provides a means for the
delivery of end-to-end QoS to applications over heterogeneous delivery of end-to-end QoS to applications over heterogeneous
networks. To support this end-to-end model, the Intserv architecture networks. To support this end-to-end model, the Intserv architecture
must be supported over a wide variety of different types of network must be supported over a wide variety of different types of network
elements. In this context, a network that supports Differentiated elements. In this context, a network that supports Differentiated
Services (Diffserv) may be viewed as a network element in the total Services (Diffserv) may be viewed as a network element in the total
end-to-end path. This document describes a framework by which end-to-end path. This document describes a framework by which
Integrated Services may be supported over Diffserv networks. Integrated Services may be supported over Diffserv networks.
Bernet, ed. et al. 1 Bernet, ed. et al. 1
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
2. Introduction 2. Introduction
Work on QoS-enabled IP networks has led to two distinct approaches: Work on QoS-enabled IP networks has led to two distinct approaches:
the Integrated Services architecture (Intserv)[10] and its the Integrated Services architecture (Intserv)[10] and its
accompanying signaling protocol, RSVP [1], and the Differentiated accompanying signaling protocol, RSVP [1], and the Differentiated
Services architecture (Diffserv)[8]. This document describes ways in Services architecture (Diffserv)[8]. This document describes ways in
which a Diffserv network can be used in the context of the Intserv which a Diffserv network can be used in the context of the Intserv
architecture to support the delivery of end-to-end QOS. architecture to support the delivery of end-to-end QOS.
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allowing end-to-end QOS to be provided to applications. One of the allowing end-to-end QOS to be provided to applications. One of the
key components of the architecture is a set of service definitions; key components of the architecture is a set of service definitions;
the current set of services consists of the controlled load and the current set of services consists of the controlled load and
guaranteed services. The architecture assumes that some explicit guaranteed services. The architecture assumes that some explicit
setup mechanism is used to convey information to routers so that setup mechanism is used to convey information to routers so that
they can provide requested services to flows that require them. they can provide requested services to flows that require them.
While RSVP is the most widely known example of such a setup While RSVP is the most widely known example of such a setup
mechanism, the Intserv architecture is designed to accommodate other mechanism, the Intserv architecture is designed to accommodate other
mechanisms. mechanisms.
Intserv services are implemented by _network elements_. While it is Intserv services are implemented by "network elements". While it is
common for network elements to be individual nodes such as routers common for network elements to be individual nodes such as routers
or links, more complex entities, such as ATM _clouds_ or 802.3 or links, more complex entities, such as ATM "clouds" or 802.3
networks may also function as network elements. As discussed in more networks may also function as network elements. As discussed in more
detail below, a Diffserv network (or _cloud_) may be viewed as a detail below, a Diffserv network (or "cloud") may be viewed as a
network element within a larger Intserv network. network element within a larger Intserv network.
2.3 RSVP 2.3 RSVP
RSVP is a signaling protocol that applications may use to request RSVP is a signaling protocol that applications may use to request
resources from the network. The network responds by explicitly resources from the network. The network responds by explicitly
admitting or rejecting RSVP requests. Certain applications that have admitting or rejecting RSVP requests. Certain applications that have
quantifiable resource requirements express these requirements using quantifiable resource requirements express these requirements using
Intserv parameters as defined in the appropriate Intserv service Intserv parameters as defined in the appropriate Intserv service
specification. As noted above, RSVP and Intserv are separable. RSVP specification. As noted above, RSVP and Intserv are separable. RSVP
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The current prevailing model of RSVP usage is based on a combined The current prevailing model of RSVP usage is based on a combined
RSVP/Intserv architecture. In this model, RSVP signals per-flow RSVP/Intserv architecture. In this model, RSVP signals per-flow
resource requirements to network elements, using Intserv parameters. resource requirements to network elements, using Intserv parameters.
These network elements apply Intserv admission control to signaled These network elements apply Intserv admission control to signaled
requests. In addition, traffic control mechanisms on the network requests. In addition, traffic control mechanisms on the network
element are configured to ensure that each admitted flow receives element are configured to ensure that each admitted flow receives
the service requested in strict isolation from other traffic. To the service requested in strict isolation from other traffic. To
Bernet, ed. et al. 2 Bernet, ed. et al. 2
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
this end, RSVP signaling configures microflow (MF) [8] packet this end, RSVP signaling configures microflow (MF) [8] packet
classifiers in Intserv capable routers along the path of the traffic classifiers in Intserv capable routers along the path of the traffic
flow. These classifiers enable per-flow classification of packets flow. These classifiers enable per-flow classification of packets
based on IP addresses and port numbers. based on IP addresses and port numbers.
The following factors have impeded deployment of RSVP (and the The following factors have impeded deployment of RSVP (and the
Intserv architecture) in the Internet at large: Intserv architecture) in the Internet at large:
1. The use of per-flow state and per-flow processing raises 1. The use of per-flow state and per-flow processing raises
scalability concerns for large networks. scalability concerns for large networks.
2. Only a small number of hosts currently generate RSVP signaling. 2. Only a small number of hosts currently generate RSVP signaling.
While this number is expected to grow dramatically, many While this number is expected to grow dramatically, many
applications may never generate RSVP signaling. applications may never generate RSVP signaling.
3. The necessary policy control mechanisms -- access control, 3. The necessary policy control mechanisms -- access control,
authentication, and accounting _- have only recently become authentication, and accounting -- have only recently become
available [17]. available [17].
2.4 Diffserv 2.4 Diffserv
The market is pushing for immediate deployment of a QoS solution In contrast to the per-flow orientation of RSVP, Diffserv networks
that addresses the needs of the Internet as well as enterprise classify packets into one of a small number of aggregated flows or
networks. This push led to the development of Diffserv. In contrast "classes", based on the Diffserv codepoint (DSCP) in the packet's IP
to the per-flow orientation of RSVP, Diffserv networks classify header. This is known as behavior aggregate (BA) classification
packets into one of a small number of aggregated flows or 'classes', [8]. At each Diffserv router, packets are subjected to a "per-hop
based on the Diffserv codepoint (DSCP) in the packet's IP header. behavior" (PHB), which is invoked by the DSCP. The primary benefit
This is known as behavior aggregate (BA) classification [8]. At each of Diffserv is its scalability. Diffserv eliminates the need for
Diffserv router, packets are subjected to a 'per-hop behavior' per-flow state and per-flow processing and therefore scales well to
(PHB), which is invoked by the DSCP. The primary benefit of Diffserv large networks.
is its scalability. Diffserv eliminates the need for per-flow state
and per-flow processing and therefore scales well to large networks.
2.5 Roles of Intserv, RSVP and Diffserv 2.5 Roles of Intserv, RSVP and Diffserv
We view Intserv, RSVP and Diffserv as complementary technologies in We view Intserv, RSVP and Diffserv as complementary technologies in
the pursuit of end-to-end QoS. Together, these mechanisms can the pursuit of end-to-end QoS. Together, these mechanisms can
facilitate deployment of applications such as IP-telephony, video- facilitate deployment of applications such as IP-telephony, video-
on-demand, and various non-multimedia mission-critical applications. on-demand, and various non-multimedia mission-critical applications.
Intserv enables hosts to request per-flow, quantifiable resources, Intserv enables hosts to request per-flow, quantifiable resources,
along end-to-end data paths and to obtain feedback regarding along end-to-end data paths and to obtain feedback regarding
admissibility of these requests. Diffserv enables scalability across admissibility of these requests. Diffserv enables scalability across
large networks. large networks.
2.6 Components of Intserv, RSVP and Diffserv 2.6 Components of Intserv, RSVP and Diffserv
Before proceeding, it is helpful to identify the following Before proceeding, it is helpful to identify the following
components of the QoS technologies described: components of the QoS technologies described:
RSVP signaling - This term refers to the standard RSVP signaling RSVP signaling - This term refers to the standard RSVP signaling
protocol. RSVP signaling is used by hosts to signal application protocol. RSVP signaling is used by hosts to signal application
resource requirements to the network (and to each other). Network resource requirements to the network (and to each other). Network
elements use RSVP signaling to return an admission control decision
to hosts. RSVP signaling may or may not carry Intserv parameters.
Bernet, ed. et al. 3 Bernet, ed. et al. 3
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
elements use RSVP signaling to return an admission control decision
to hosts. RSVP signaling may or may not carry Intserv parameters.
Admission control at a network element may or may not be based on Admission control at a network element may or may not be based on
the Intserv model. the Intserv model.
MF traffic control - This term refers to traffic control which is MF traffic control - This term refers to traffic control which is
applied independently to individual traffic flows and therefore applied independently to individual traffic flows and therefore
requires recognizing individual traffic flows via MF classification. requires recognizing individual traffic flows via MF classification.
Aggregate traffic control - This term refers to traffic control Aggregate traffic control - This term refers to traffic control
which is applied collectively to sets of traffic flows. These sets which is applied collectively to sets of traffic flows. These sets
of traffic flows are recognized based on BA (DSCP) classification. of traffic flows are recognized based on BA (DSCP) classification.
In this draft, we use the terms 'aggregate traffic control' and In this document, we use the terms "aggregate traffic control" and
'Diffserv' interchangeably. "Diffserv" interchangeably.
Aggregate RSVP. While the existing definition of RSVP supports only Aggregate RSVP. While the existing definition of RSVP supports only
per-flow reservations, extensions to RSVP are being developed to per-flow reservations, extensions to RSVP are being developed to
enable RSVP reservations to be made for aggregated traffic, i.e. enable RSVP reservations to be made for aggregated traffic, i.e.
sets of flows that may be recognized by BA classification. This use sets of flows that may be recognized by BA classification. This use
of RSVP may be useful in controlling the allocation of bandwidth in of RSVP may be useful in controlling the allocation of bandwidth in
Diffserv networks. Diffserv networks.
Per-flow RSVP. The conventional usage of RSVP to perform resource Per-flow RSVP. The conventional usage of RSVP to perform resource
reservations for individual microflows. reservations for individual microflows.
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only BA classification is performed inside the Diffserv region. only BA classification is performed inside the Diffserv region.
Non-Diffserv Region. The portions of the network outside the Non-Diffserv Region. The portions of the network outside the
Diffserv region. Such a region may also offer a variety of different Diffserv region. Such a region may also offer a variety of different
types of classification and traffic control. types of classification and traffic control.
Note that, for the purposes of this document, the defining features Note that, for the purposes of this document, the defining features
of a Diffserv region is the type of classification and traffic of a Diffserv region is the type of classification and traffic
control that is used for the delivery of end-to-end QOS for a control that is used for the delivery of end-to-end QOS for a
particular application. Thus, while it may not be possible to particular application. Thus, while it may not be possible to
identify a certain region as _purely Diffserv_ with respect to all identify a certain region as "purely Diffserv" with respect to all
traffic flowing through the region, it is possible to define it in traffic flowing through the region, it is possible to define it in
this way from the perspective of the treatment of traffic from a this way from the perspective of the treatment of traffic from a
single application. single application.
2.7 The Framework 2.7 The Framework
In the framework we present, end-to-end, quantitative QoS is
provided by applying the Intserv model end-to-end across a network
Bernet, ed. et al. 4 Bernet, ed. et al. 4
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
In the framework we present, end-to-end, quantitative QoS is
provided by applying the Intserv model end-to-end across a network
containing one or more Diffserv regions. The Diffserv regions may, containing one or more Diffserv regions. The Diffserv regions may,
but are not required to, participate in end-to-end RSVP signaling but are not required to, participate in end-to-end RSVP signaling
for the purpose of optimizing resource allocation and supporting for the purpose of optimizing resource allocation and supporting
admission control. admission control.
From the perspective of Intserv, Diffserv regions of the network are From the perspective of Intserv, Diffserv regions of the network are
treated as virtual links connecting Intserv capable routers or hosts treated as virtual links connecting Intserv capable routers or hosts
(much as an 802.1p network region is treated as a virtual link in (much as an 802.1p network region is treated as a virtual link in
[5]). Within the Diffserv regions of the network routers implement [5]). Within the Diffserv regions of the network routers implement
specific PHBs (aggregate traffic control). The total amount of specific PHBs (aggregate traffic control). The total amount of
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Note that this discussion is in the context of servicing Note that this discussion is in the context of servicing
quantitative QoS applications specifically. By this we mean those quantitative QoS applications specifically. By this we mean those
applications that are able to quantify their traffic and QoS applications that are able to quantify their traffic and QoS
requirements. requirements.
3.1 Resource Based Admission Control 3.1 Resource Based Admission Control
In Intserv networks, quantitative QoS applications use an explicit In Intserv networks, quantitative QoS applications use an explicit
setup mechanism (e.g. RSVP) to request resources from the network. setup mechanism (e.g. RSVP) to request resources from the network.
The network may accept or reject these requests in response. This is The network may accept or reject these requests in response. This is
'explicit admission control'. Explicit admission control helps to "explicit admission control". Explicit admission control helps to
assure that network resources are optimally used. To further assure that network resources are optimally used. To further
understand this issue, consider a Diffserv network region providing
only aggregate traffic control with no signaling. In the Diffserv
Bernet, ed. et al. 5 Bernet, ed. et al. 5
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
understand this issue, consider a Diffserv network region providing
only aggregate traffic control with no signaling. In the Diffserv
network region, admission control is applied implicitly by network region, admission control is applied implicitly by
provisioning policing parameters at network elements. For example, a provisioning policing parameters at network elements. For example, a
network element at the ingress to a Diffserv network region could be network element at the ingress to a Diffserv network region could be
provisioned to accept only 50 Kbps of traffic for the EF DSCP. provisioned to accept only 50 Kbps of traffic for the EF DSCP.
While such implicit admission control does protect the network to While such implicit admission control does protect the network to
some degree, it can be quite ineffective. For example, consider that some degree, it can be quite ineffective. For example, consider that
there may be 10 IP telephony sessions originating outside the there may be 10 IP telephony sessions originating outside the
Diffserv network region, each requiring 10 Kbps of EF service from Diffserv network region, each requiring 10 Kbps of EF service from
the Diffserv network region. Since the network element protecting the Diffserv network region. Since the network element protecting
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intercepted by RSVP-aware network elements and can be reviewed intercepted by RSVP-aware network elements and can be reviewed
against policies stored in policy databases. These resource requests against policies stored in policy databases. These resource requests
securely identify the user and the application for which the securely identify the user and the application for which the
resources are requested. Consequently, the network element is able resources are requested. Consequently, the network element is able
to consider per-user and/or per-application policy when deciding to consider per-user and/or per-application policy when deciding
whether or not to admit a resource request. So, in addition to whether or not to admit a resource request. So, in addition to
optimizing the use of resources in a Diffserv network region (as optimizing the use of resources in a Diffserv network region (as
discussed in 3.1) RSVP conversant admission control agents can be discussed in 3.1) RSVP conversant admission control agents can be
used to apply specific customer policies in determining the specific used to apply specific customer policies in determining the specific
customer traffic flows entitled to use the Diffserv network region's customer traffic flows entitled to use the Diffserv network region's
resources. Customer policies can be used to allocate resources to
specific users and/or applications.
Bernet, ed. et al. 6 Bernet, ed. et al. 6
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
resources. Customer policies can be used to allocate resources to
specific users and/or applications.
By comparison, in Diffserv network regions without RSVP signaling, By comparison, in Diffserv network regions without RSVP signaling,
policies are typically applied based on the Diffserv customer policies are typically applied based on the Diffserv customer
network from which traffic originates, not on the originating user network from which traffic originates, not on the originating user
or application within the customer network. or application within the customer network.
3.3 Assistance in Traffic Identification/Classification 3.3 Assistance in Traffic Identification/Classification
Within Diffserv network regions, traffic is allotted service based Within Diffserv network regions, traffic is allotted service based
on the DSCP marked in each packet's IP header. Thus, in order to on the DSCP marked in each packet's IP header. Thus, in order to
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marking, routers in the network are configured to identify specific marking, routers in the network are configured to identify specific
traffic (typically based on MF classification) and to mark the DSCP traffic (typically based on MF classification) and to mark the DSCP
as packets transit the router. There are advantages and as packets transit the router. There are advantages and
disadvantages to each scheme. Regardless of the scheme used, disadvantages to each scheme. Regardless of the scheme used,
explicit signaling offers significant benefits. explicit signaling offers significant benefits.
3.3.1 Host Marking 3.3.1 Host Marking
In the case of host marking, the host operating system marks the In the case of host marking, the host operating system marks the
DSCP in transmitted packets. This approach has the benefit of DSCP in transmitted packets. This approach has the benefit of
shifting per-flow classification and marking to the edge of the shifting per-flow classification and marking to the source of the
network, where it scales best. It also enables the host to make traffic, where it scales best. It also enables the host to make
decisions regarding the mark that is appropriate for each decisions regarding the mark that is appropriate for each
transmitted packet and hence the relative importance attached to transmitted packet and hence the relative importance attached to
each packet. The host is generally better equipped to make this each packet. The host is generally better equipped to make this
decision than the network. Furthermore, if IPSEC encryption is used, decision than the network. Furthermore, if IPSEC encryption is used,
the host may be the only device in the network that is able to make the host may be the only device in the network that is able to make
a meaningful determination of the appropriate marking for each a meaningful determination of the appropriate marking for each
packet. packet.
Host marking requires that the host be aware of the interpretation Host marking requires that the host be aware of the interpretation
of DSCPs by the network. This information can be configured into of DSCPs by the network. This information can be configured into
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3.3.2 Router Marking 3.3.2 Router Marking
In the case of router marking, MF classification criteria must be In the case of router marking, MF classification criteria must be
configured in the router. This may be done dynamically, by request configured in the router. This may be done dynamically, by request
from the host operating system, or statically via manual from the host operating system, or statically via manual
configuration or via automated scripts. configuration or via automated scripts.
Bernet, ed. et al. 7 Bernet, ed. et al. 7
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There are significant difficulties in doing so statically. There are significant difficulties in doing so statically.
Typically, it is desirable to allot service to traffic based on the Typically, it is desirable to allot service to traffic based on the
application and/or user originating the traffic. At times it is application and/or user originating the traffic. At times it is
possible to identify packets associated with a specific application possible to identify packets associated with a specific application
by the IP port numbers in the headers. It may also be possible to by the IP port numbers in the headers. It may also be possible to
identify packets originating from a specific user by the source IP identify packets originating from a specific user by the source IP
address. However, such classification criteria may change address. However, such classification criteria may change
frequently. Users may be assigned different IP addresses by DHCP. frequently. Users may be assigned different IP addresses by DHCP.
Applications may use transient ports. To further complicate matters, Applications may use transient ports. To further complicate matters,
multiple users may share an IP address. These factors make it very multiple users may share an IP address. These factors make it very
difficult to manage static configuration of the classification difficult to manage static configuration of the classification
information required to mark traffic in routers. information required to mark traffic in routers.
An attractive alternative to static configuration is to allow host An attractive alternative to static configuration is to allow host
operating systems to signal classification criteria to the router on operating systems to signal classification criteria to the router on
behalf of users and applications. As we will show later in this behalf of users and applications. As we will show later in this
draft, RSVP signaling is ideally suited for this task. In addition document, RSVP signaling is ideally suited for this task. In
to enabling dynamic and accurate updating of MF classification addition to enabling dynamic and accurate updating of MF
criteria, RSVP signaling enables classification of IPSEC [13] classification criteria, RSVP signaling enables classification of
packets (by use of the SPI) which would otherwise be unrecognizable. IPSEC [13] packets (by use of the SPI) which would otherwise be
unrecognizable.
3.4 Traffic Conditioning 3.4 Traffic Conditioning
Intserv-capable network elements are able to condition traffic at a Intserv-capable network elements are able to condition traffic at a
per-flow granularity, by some combination of shaping and/or per-flow granularity, by some combination of shaping and/or
policing. Pre-conditioning traffic in this manner before it is policing. Pre-conditioning traffic in this manner before it is
submitted to the Diffserv region of the network is beneficial. In submitted to the Diffserv region of the network is beneficial. In
particular, it enhances the ability of the Diffserv region of the particular, it enhances the ability of the Diffserv region of the
network to provide quantitative services using aggregate traffic network to provide quantitative services using aggregate traffic
control. control.
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first, resources within the Diffserv regions of the network are first, resources within the Diffserv regions of the network are
statically provisioned and these regions include no RSVP aware statically provisioned and these regions include no RSVP aware
devices. In the second, resources within the Diffserv region of the devices. In the second, resources within the Diffserv region of the
network are dynamically provisioned and select devices within the network are dynamically provisioned and select devices within the
Diffserv network regions participate in RSVP signaling. Diffserv network regions participate in RSVP signaling.
4.1 Reference Network 4.1 Reference Network
Bernet, ed. et al. 8 Bernet, ed. et al. 8
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
The two realizations of the framework will be discussed in the The two realizations of the framework will be discussed in the
context of the following reference network: context of the following reference network:
________ ______________ ________
/ \ / \ / \ / \ / \ / \
/ \ / \ / \ / \ / \ / \
|---| | |---| |---| |---| |---| | |---| |---| | |---| |---| |---| |---| | |---|
|Tx |-| |ER1|---|BR1| |BR2|---|ER2| |-|Rx | |Tx |-| |ER1|---|BR1| |BR2|---|ER2| |-|Rx |
|---| | |-- | |---| |---| |---| | |---| |---| | |-- | |---| |---| |---| | |---|
\ / \ / \ / \ / \ / \ /
\______ / \___ _________ / \__ _____/ \________/ \______________/ \________/
Non-Diffserv region Diffserv region Non-Diffserv region Non-Diffserv region Diffserv region Non-Diffserv region
Figure 1: Sample Network Configuration Figure 1: Sample Network Configuration
The reference network includes a Diffserv region in the middle of a The reference network includes a Diffserv region in the middle of a
larger network supporting Intserv end-to-end. The Diffserv region larger network supporting Intserv end-to-end. The Diffserv region
contains a mesh of routers, at least some of which provide aggregate contains a mesh of routers, at least some of which provide aggregate
traffic control. The regions outside the Diffserv region (non- traffic control. The regions outside the Diffserv region (non-
Diffserv regions) contain meshes of routers and attached hosts, at Diffserv regions) contain meshes of routers and attached hosts, at
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In the interest of simplicity we consider a single QoS sender, Tx In the interest of simplicity we consider a single QoS sender, Tx
communicating across this network with a single QoS receiver, Rx. communicating across this network with a single QoS receiver, Rx.
The edge routers (ER1, ER2) which are adjacent to the Diffserv The edge routers (ER1, ER2) which are adjacent to the Diffserv
region interface to the border routers (BR1, BR2) within the region interface to the border routers (BR1, BR2) within the
Diffserv region. Diffserv region.
From an economic viewpoint, we may consider that the Diffserv region From an economic viewpoint, we may consider that the Diffserv region
sells service to the network outside the Diffserv region, which in sells service to the network outside the Diffserv region, which in
turn provides service to hosts. Thus, we may think of the non- turn provides service to hosts. Thus, we may think of the non-
Diffserv regions as customers of the Diffserv region. In the Diffserv regions as clients or customers of the Diffserv region. In
following, we use the term 'customer' for the non-Diffserv regions. the following, we use the term "customer" for the non-Diffserv
Note that the boundaries of the regions may or may not align with regions. Note that the boundaries of the regions may or may not
administrative domain boundaries, and that a single region might align with administrative domain boundaries, and that a single
contain multiple administrative domains. region might contain multiple administrative domains.
We now define the major components of the reference network. We now define the major components of the reference network.
4.1.1 Hosts 4.1.1 Hosts
We assume that both sending and receiving hosts use RSVP to We assume that both sending and receiving hosts use RSVP to
communicate the quantitative QoS requirements of QoS-aware communicate the quantitative QoS requirements of QoS-aware
applications running on the host. In principle, other mechanisms may applications running on the host. In principle, other mechanisms may
be used to establish resource reservations in Intserv-capable nodes, be used to establish resource reservations in Intserv-capable nodes,
but RSVP is clearly the prevalent mechanism for this purpose. but RSVP is clearly the prevalent mechanism for this purpose.
Typically, a QoS process within the host operating system generates Typically, a QoS process within the host operating system generates
RSVP signaling on behalf of applications. This process may also RSVP signaling on behalf of applications. This process may also
invoke local traffic control. invoke local traffic control.
Bernet, ed. et al. 9 Bernet, ed. et al. 9
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
As discussed above, traffic control in the host may mark the DSCP in As discussed above, traffic control in the host may mark the DSCP in
transmitted packets, and shape transmitted traffic to the transmitted packets, and shape transmitted traffic to the
requirements of the Intserv service in use. Alternatively, the first requirements of the Intserv service in use. Alternatively, the first
Intserv-capable router downstream from the host may provide these Intserv-capable router downstream from the host may provide these
traffic control functions. traffic control functions.
4.1.2 End-to-End RSVP Signaling 4.1.2 End-to-End RSVP Signaling
We assume that RSVP signaling messages travel end-to-end between We assume that RSVP signaling messages travel end-to-end between
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and the agreement negotiated with the customer (aggregate traffic and the agreement negotiated with the customer (aggregate traffic
control). In the case in which the Diffserv network region is RSVP- control). In the case in which the Diffserv network region is RSVP-
aware, the border routers participate in RSVP signaling and act as aware, the border routers participate in RSVP signaling and act as
admission control agents for the Diffserv network region. admission control agents for the Diffserv network region.
We will later describe the functionality of the border routers in We will later describe the functionality of the border routers in
greater depth for each of the two realizations of the framework. greater depth for each of the two realizations of the framework.
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4.1.5 Diffserv Network Region 4.1.5 Diffserv Network Region
The Diffserv network region supports aggregate traffic control and The Diffserv network region supports aggregate traffic control and
is assumed not to be capable of MF classification. Depending on the is assumed not to be capable of MF classification. Depending on the
specific realization of the framework, some number of routers within specific realization of the framework, some number of routers within
the Diffserv region may be RSVP aware and therefore capable of per- the Diffserv region may be RSVP aware and therefore capable of per-
flow signaling and admission control. If devices in the Diffserv flow signaling and admission control. If devices in the Diffserv
region are not RSVP aware, they will pass RSVP messages region are not RSVP aware, they will pass RSVP messages
transparently with negligible performance impact (see [6]). transparently with negligible performance impact (see [6]).
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although this might not be required in the case of over- although this might not be required in the case of over-
provisioning. Even if these elements are not Intserv capable, we provisioning. Even if these elements are not Intserv capable, we
assume that they will pass RSVP messages unhindered. Routers outside assume that they will pass RSVP messages unhindered. Routers outside
of the Diffserv network region are not precluded from providing of the Diffserv network region are not precluded from providing
aggregate traffic control to some subset of the traffic passing aggregate traffic control to some subset of the traffic passing
through them. through them.
4.2 Service Mapping 4.2 Service Mapping
Intserv service requests specify an Intserv service type and a set Intserv service requests specify an Intserv service type and a set
of quantitative parameters known as a 'flowspec'. At each hop in an of quantitative parameters known as a "flowspec". At each hop in an
Intserv network, the Intserv service requests are interpreted in a Intserv network, the Intserv service requests are interpreted in a
form meaningful to the specific link layer medium. For example at form meaningful to the specific link layer medium. For example at
an 802.1 hop, the Intserv parameters are mapped to an appropriate an 802.1 hop, the Intserv parameters are mapped to an appropriate
802.1p priority level [5]. 802.1p priority level [5].
In our framework, Diffserv regions of the network are analogous to In our framework, Diffserv regions of the network are analogous to
the 802.1p capable switched segments described in [5]. Requests for the 802.1p capable switched segments described in [5]. Requests for
Intserv services must be mapped onto the underlying capabilities of Intserv services must be mapped onto the underlying capabilities of
the Diffserv network region. Aspects of the mapping include: the Diffserv network region. Aspects of the mapping include:
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service; service;
- performing appropriate policing (including, perhaps, shaping or - performing appropriate policing (including, perhaps, shaping or
remarking) at the edges of the Diffserv region; remarking) at the edges of the Diffserv region;
- exporting Intserv parameters from the Diffserv region (e.g. for - exporting Intserv parameters from the Diffserv region (e.g. for
the updating of ADSPECs); the updating of ADSPECs);
- performing admission control on the Intserv requests that takes - performing admission control on the Intserv requests that takes
into account the resource availability in the Diffserv region. into account the resource availability in the Diffserv region.
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Exactly how these functions are performed will be a function of the Exactly how these functions are performed will be a function of the
way bandwidth is managed inside the Diffserv network region, which way bandwidth is managed inside the Diffserv network region, which
is a topic we discuss in Section 4.3. is a topic we discuss in Section 4.3.
When the PHB (or set of PHBs) has been selected for a particular When the PHB (or set of PHBs) has been selected for a particular
Intserv flow, it may be necessary to communicate the choice of DSCP Intserv flow, it may be necessary to communicate the choice of DSCP
for the flow to other network elements. Two schemes may be used to for the flow to other network elements. Two schemes may be used to
achieve this end, as discussed below. achieve this end, as discussed below.
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generally the most appropriate location for microflow policing, generally the most appropriate location for microflow policing,
since it pushes per-flow work to the edges of the network, where it since it pushes per-flow work to the edges of the network, where it
scales better. In addition, since Intserv-capable routers outside scales better. In addition, since Intserv-capable routers outside
the Diffserv region are responsible for providing microflow service the Diffserv region are responsible for providing microflow service
to their customers and the Diffserv region is responsible for to their customers and the Diffserv region is responsible for
providing aggregate service to its customers, this distribution of providing aggregate service to its customers, this distribution of
functionality mirrors the distribution of responsibility. functionality mirrors the distribution of responsibility.
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2. Providing per microflow policing at the border routers - this 2. Providing per microflow policing at the border routers - this
approach tends to be less scalable than the previous approach. It approach tends to be less scalable than the previous approach. It
also imposes a management burden on the Diffserv region of the also imposes a management burden on the Diffserv region of the
network. However, it may be appropriate in certain cases, for the network. However, it may be appropriate in certain cases, for the
Diffserv boundary routers to offer per microflow policing as a Diffserv boundary routers to offer per microflow policing as a
value-add to its Intserv customers. value-add to its Intserv customers.
3. Relying on upstream shaping and policing - in certain cases, the 3. Relying on upstream shaping and policing - in certain cases, the
customer may trust the shaping of certain groups of hosts customer may trust the shaping of certain groups of hosts
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region is RSVP aware. region is RSVP aware.
5.1 Statically Provisioned Diffserv Network Region 5.1 Statically Provisioned Diffserv Network Region
In this example, no devices in the Diffserv network region are RSVP In this example, no devices in the Diffserv network region are RSVP
aware. The Diffserv network region is statically provisioned. The aware. The Diffserv network region is statically provisioned. The
customer(s) of the Diffserv network regions and the owner of the customer(s) of the Diffserv network regions and the owner of the
Diffserv network region have negotiated a static contract (service Diffserv network region have negotiated a static contract (service
level specification, or SLS) for the transmit capacity to be level specification, or SLS) for the transmit capacity to be
provided to the customer at each of a number of standard Diffserv provided to the customer at each of a number of standard Diffserv
service levels. The _transmit capacity_ may be simply an amount of service levels. The "transmit capacity" may be simply an amount of
Bernet, ed. et al. 13 Bernet, ed. et al. 13
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bandwidth or it could be a more complex _profile_ involving a number bandwidth or it could be a more complex "profile" involving a number
of factors such as burst size, peak rate, time of day etc. of factors such as burst size, peak rate, time of day etc.
It is helpful to consider each edge router in the customer network It is helpful to consider each edge router in the customer network
as consisting of two halves, a standard Intserv half, which as consisting of two halves, a standard Intserv half, which
interfaces to the customer's network regions and a Diffserv half interfaces to the customer's network regions and a Diffserv half
which interfaces to the Diffserv network region. The Intserv half is which interfaces to the Diffserv network region. The Intserv half is
able to identify and process traffic on per-flow granularity. able to identify and process traffic on per-flow granularity.
The Diffserv half of the router can be considered to consist of a The Diffserv half of the router can be considered to consist of a
number of virtual transmit interfaces, one for each Diffserv service number of virtual transmit interfaces, one for each Diffserv service
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if resources are deemed insufficient to carry the traffic requested. if resources are deemed insufficient to carry the traffic requested.
7. At ER2, the RESV message is subjected to standard RSVP/Intserv 7. At ER2, the RESV message is subjected to standard RSVP/Intserv
processing. It may be rejected if resources on the downstream processing. It may be rejected if resources on the downstream
interface of ER2 are deemed insufficient to carry the resources interface of ER2 are deemed insufficient to carry the resources
requested. If it is not rejected, it will be carried transparently requested. If it is not rejected, it will be carried transparently
through the Diffserv network region, arriving at ER1. through the Diffserv network region, arriving at ER1.
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8. In ER1, the RESV message triggers admission control processing. 8. In ER1, the RESV message triggers admission control processing.
ER1 compares the resources requested in the RSVP/Intserv request to ER1 compares the resources requested in the RSVP/Intserv request to
the resources available in the Diffserv network region at the the resources available in the Diffserv network region at the
corresponding Diffserv service level. The corresponding service corresponding Diffserv service level. The corresponding service
level is determined by the Intserv to Diffserv mapping discussed level is determined by the Intserv to Diffserv mapping discussed
previously. The availability of resources is determined by the previously. The availability of resources is determined by the
capacity provisioned in the SLS. ER1 may also apply a policy capacity provisioned in the SLS. ER1 may also apply a policy
decision such that the resource request may be rejected based on the decision such that the resource request may be rejected based on the
customer's specific policy criteria, even though the aggregate customer's specific policy criteria, even though the aggregate
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routers. The border router, BR1 is RSVP aware. In addition, there routers. The border router, BR1 is RSVP aware. In addition, there
may be other routers within the Diffserv network region which are may be other routers within the Diffserv network region which are
RSVP aware. Note that although these routers are able to participate RSVP aware. Note that although these routers are able to participate
in some form of RSVP signaling, they classify and schedule traffic in some form of RSVP signaling, they classify and schedule traffic
in aggregate, based on DSCP, not on the per-flow classification in aggregate, based on DSCP, not on the per-flow classification
criteria used by standard RSVP/Intserv routers. It can be said that criteria used by standard RSVP/Intserv routers. It can be said that
their control-plane is RSVP while their data-plane is Diffserv. This their control-plane is RSVP while their data-plane is Diffserv. This
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approach exploits the benefits of RSVP signaling while maintaining approach exploits the benefits of RSVP signaling while maintaining
much of the scalability associated with Diffserv. much of the scalability associated with Diffserv.
In the preceding example, there is no signaling between the Diffserv In the preceding example, there is no signaling between the Diffserv
network region and network elements outside it. The negotiation of network region and network elements outside it. The negotiation of
an SLS is the only explicit exchange of resource availability an SLS is the only explicit exchange of resource availability
information between the two network regions. ER1 is configured with information between the two network regions. ER1 is configured with
the information represented by the SLS and as such, is able to act the information represented by the SLS and as such, is able to act
as an admission control agent for the Diffserv network region. Such as an admission control agent for the Diffserv network region. Such
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result, changes in the capacity available in the Diffserv network result, changes in the capacity available in the Diffserv network
region can be indicated to the Intserv-capable nodes outside the region can be indicated to the Intserv-capable nodes outside the
Diffserv region via RSVP. By including routers interior to the Diffserv region via RSVP. By including routers interior to the
Diffserv network region in RSVP signaling, it is possible to Diffserv network region in RSVP signaling, it is possible to
simultaneously improve the efficiency of resource usage within the simultaneously improve the efficiency of resource usage within the
Diffserv region and to improve the level of confidence that the Diffserv region and to improve the level of confidence that the
resources requested at admission control are indeed available at resources requested at admission control are indeed available at
this particular point in time. This is because admission control can this particular point in time. This is because admission control can
be linked to the availability of resources along the specific path be linked to the availability of resources along the specific path
that would be impacted. We refer to this benefit of RSVP signaling that would be impacted. We refer to this benefit of RSVP signaling
as 'topology aware admission control'. A further benefit of as "topology aware admission control". A further benefit of
supporting RSVP signaling within the Diffserv network region is that supporting RSVP signaling within the Diffserv network region is that
it is possible to effect changes in the provisioning of the Diffserv it is possible to effect changes in the provisioning of the Diffserv
network region (e.g., allocating more or less bandwidth to the EF network region (e.g., allocating more or less bandwidth to the EF
queue in a router) in response to resource requests from outside of queue in a router) in response to resource requests from outside of
the Diffserv region. the Diffserv region.
Various mechanisms may be used within the Diffserv network region to Various mechanisms may be used within the Diffserv network region to
support dynamic provisioning and topology aware admission control. support dynamic provisioning and topology aware admission control.
These include aggregated RSVP, per-flow RSVP and bandwidth brokers, These include aggregated RSVP, per-flow RSVP and bandwidth brokers,
as described in the following paragraphs. as described in the following paragraphs.
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other border routers using aggregated RSVP to reserve resources other border routers using aggregated RSVP to reserve resources
between edges of the Diffserv network region. Initial reservation between edges of the Diffserv network region. Initial reservation
levels for each service level may be established between major levels for each service level may be established between major
border routers, based on anticipated traffic patterns. Border border routers, based on anticipated traffic patterns. Border
routers could trigger changes in reservation levels as a result of routers could trigger changes in reservation levels as a result of
the cumulative per-flow RSVP requests from the non-Diffserv regions the cumulative per-flow RSVP requests from the non-Diffserv regions
reaching high or low-water marks. reaching high or low-water marks.
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In this approach, admission of per-flow RSVP requests from nods In this approach, admission of per-flow RSVP requests from nodes
outside the Diffserv region would be counted against the appropriate outside the Diffserv region would be counted against the appropriate
aggregate reservations for the corresponding service level. The size aggregate reservations for the corresponding service level. The size
of the aggregate reservations may or may not be dynamically adjusted of the aggregate reservations may or may not be dynamically adjusted
to deal with the changes in per-flow reservations. to deal with the changes in per-flow reservations.
The advantage of this approach is that it offers dynamic, topology The advantage of this approach is that it offers dynamic, topology
aware admission control to the Diffserv network region without aware admission control to the Diffserv network region without
requiring the level of RSVP signaling processing that would be requiring the level of RSVP signaling processing that would be
required to support per-flow RSVP. required to support per-flow RSVP.
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approach provides the benefits of the previous approach (dynamic, approach provides the benefits of the previous approach (dynamic,
topology aware admission control) without requiring aggregated RSVP topology aware admission control) without requiring aggregated RSVP
support. Resources are also used more efficiently as a result of the support. Resources are also used more efficiently as a result of the
per-flow admission control. However, the demands on RSVP signaling per-flow admission control. However, the demands on RSVP signaling
resources within the Diffserv network region may be significantly resources within the Diffserv network region may be significantly
higher than in an aggregated RSVP approach. higher than in an aggregated RSVP approach.
Note that per-flow RSVP and aggregated RSVP are not mutually Note that per-flow RSVP and aggregated RSVP are not mutually
exclusive in a single Diffserv region. It is possible to use per- exclusive in a single Diffserv region. It is possible to use per-
flow RSVP at the edges of the Diffserv region and aggregation only flow RSVP at the edges of the Diffserv region and aggregation only
in some _core_ region within the Diffserv region. in some "core" region within the Diffserv region.
5.2.4 Granularity of Deployment of RSVP Aware Routers 5.2.4 Granularity of Deployment of RSVP Aware Routers
In 5.2.2 and 5.2.3 some subset of the routers within the Diffserv In 5.2.2 and 5.2.3 some subset of the routers within the Diffserv
network is RSVP signaling aware (though traffic control is network is RSVP signaling aware (though traffic control is
aggregated as opposed to per-flow). The relative number of routers aggregated as opposed to per-flow). The relative number of routers
in the core that participate in RSVP signaling is a provisioning in the core that participate in RSVP signaling is a provisioning
decision that must be made by the network administrator. decision that must be made by the network administrator.
In one extreme case, only the border routers participate in RSVP In one extreme case, only the border routers participate in RSVP
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else it must be carefully and statically provisioned for limited else it must be carefully and statically provisioned for limited
traffic patterns. The border routers must enforce these patterns. traffic patterns. The border routers must enforce these patterns.
In the other extreme case, each router in the Diffserv network In the other extreme case, each router in the Diffserv network
region might participate in RSVP signaling. In this case, resources region might participate in RSVP signaling. In this case, resources
can be used with optimal efficiency, but signaling processing can be used with optimal efficiency, but signaling processing
requirements and associated overhead increase. As noted above, RSVP requirements and associated overhead increase. As noted above, RSVP
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Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
aggregation is one way to limit the signaling overhead at the cost aggregation is one way to limit the signaling overhead at the cost
of some loss of optimality in resource utilization. of some loss of optimality in resource utilization.
It is likely that some network administrators will compromise by It is likely that some network administrators will compromise by
enabling RSVP signaling on some subset of routers in the Diffserv enabling RSVP signaling on some subset of routers in the Diffserv
network region. These routers will likely represent major traffic network region. These routers will likely represent major traffic
switching points with over-provisioned or statically provisioned switching points with over-provisioned or statically provisioned
regions of RSVP unaware routers between them. regions of RSVP unaware routers between them.
5.3 Dynamically Provisioned, Non-RSVP-aware Diffserv Region 5.3 Dynamically Provisioned, Non-RSVP-aware Diffserv Region
Border routers might not use any form of RSVP signaling within the Border routers might not use any form of RSVP signaling within the
Diffserv network region but might instead use custom protocols to Diffserv network region but might instead use custom protocols to
interact with an 'oracle'. The oracle is a hypothetical agent that interact with an "oracle". The oracle is a hypothetical agent that
has sufficient knowledge of resource availability and network has sufficient knowledge of resource availability and network
topology to make admission control decisions. The set of RSVP aware topology to make admission control decisions. The set of RSVP aware
routers in the previous two examples can be considered collectively routers in the previous two examples can be considered collectively
as a form of distributed oracle. In various definitions of the as a form of distributed oracle. In various definitions of the
'bandwidth broker' [4], it is able to act as a centralized oracle. "bandwidth broker" [4], it is able to act as a centralized oracle.
6. Implications of the Framework for Diffserv Network Regions 6. Implications of the Framework for Diffserv Network Regions
We have described a framework in which RSVP/Intserv style QoS can be We have described a framework in which RSVP/Intserv style QoS can be
provided across end-to-end paths that include Diffserv network provided across end-to-end paths that include Diffserv network
regions. This section discusses some of the implications of this regions. This section discusses some of the implications of this
framework for the Diffserv network region. framework for the Diffserv network region.
6.1 Requirements from Diffserv Network Regions 6.1 Requirements from Diffserv Network Regions
A Diffserv network region must meet the following requirements in A Diffserv network region must meet the following requirements in
order for it to support the framework described in this draft. order for it to support the framework described in this document.
1. A Diffserv network region must be able to provide support for the 1. A Diffserv network region must be able to provide support for the
standard Intserv QoS services between its border routers. It must be standard Intserv QoS services between its border routers. It must be
possible to invoke these services by use of standard PHBs within the possible to invoke these services by use of standard PHBs within the
Diffserv region and appropriate behavior at the edge of the Diffserv Diffserv region and appropriate behavior at the edge of the Diffserv
region. region.
2. Diffserv network regions must provide admission control 2. Diffserv network regions must provide admission control
information to their _customer_ (non-Diffserv) network regions. information to their "customer" (non-Diffserv) network regions.
This information can be provided by a dynamic protocol or through This information can be provided by a dynamic protocol or through
static service level agreements enforced at the edges of the static service level agreements enforced at the edges of the
Diffserv region. Diffserv region.
3. Diffserv network regions must be able to pass RSVP messages, in 3. Diffserv network regions must be able to pass RSVP messages, in
such a manner that they can be recovered at the egress of the such a manner that they can be recovered at the egress of the
Diffserv network region. The Diffserv network region may, but is not Diffserv network region. The Diffserv network region may, but is not
required to, process these messages. Mechanisms for transparently required to, process these messages. Mechanisms for transparently
carrying RSVP messages across a transit network are described in carrying RSVP messages across a transit network are described in
[3,6,15, 16]. [3,6,15, 16].
Bernet, ed. et al. 18 Bernet, ed. et al. 18
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To meet these requirements, additional work is required in the areas To meet these requirements, additional work is required in the areas
of: of:
1. Mapping Intserv style service specifications to services that can 1. Mapping Intserv style service specifications to services that can
be provided by Diffserv network regions. be provided by Diffserv network regions.
2. Definition of the functionality required in network elements to 2. Definition of the functionality required in network elements to
support RSVP signaling with aggregate traffic control (for network support RSVP signaling with aggregate traffic control (for network
elements residing in the Diffserv network region). elements residing in the Diffserv network region).
3. Definition of mechanisms to efficiently and dynamically provision 3. Definition of mechanisms to efficiently and dynamically provision
resources in a Diffserv network region (e.g. aggregated RSVP, resources in a Diffserv network region (e.g. aggregated RSVP,
tunneling, MPLS, etc.). This might include protocols by which an tunneling, MPLS, etc.). This might include protocols by which an
_oracle_ conveys information about resource availability within a "oracle" (e.g., a centralized server) conveys information about
Diffserv region to border routers. resource availability within a Diffserv region to border routers.
One example of such a mechanism is the so-called "bandwidth broker"
proposed in [19, 20, 21].
6.2 Protection of Intserv Traffic from Other Traffic 6.2 Protection of Intserv Traffic from Other Traffic
Network administrators must be able to share resources in the Network administrators must be able to share resources in the
Diffserv network region between three types of traffic: Diffserv network region between three types of traffic:
a. End-to-end Intserv traffic - this is typically traffic a. End-to-end Intserv traffic - this is typically traffic
associated with quantitative QoS applications. It requires a associated with quantitative QoS applications. It requires a
specific quantity of resources with a high degree of assurance. specific quantity of resources with a high degree of assurance.
b. Non-Intserv traffic. The Diffserv region may allocate resources b. Non-Intserv traffic. The Diffserv region may allocate resources
to traffic that does not make use of Intserv techniques to quantify to traffic that does not make use of Intserv techniques to quantify
its requirements, e.g. through the use of static provisioning and its requirements, e.g. through the use of static provisioning and
SLSs enforced at the edges of the region. Such traffic might be SLSs enforced at the edges of the region. Such traffic might be
associated with applications whose QoS requirements are not readily associated with applications whose QoS requirements are not readily
quantifiable but which require a 'better than best-effort' level of quantifiable but which require a "better than best-effort" level of
service. service.
c. All other (best-effort) traffic c. All other (best-effort) traffic
These three classes of traffic must be isolated from each other by These three classes of traffic must be isolated from each other by
the appropriate configuration of policers and classifiers at ingress the appropriate configuration of policers and classifiers at ingress
points to the Diffserv network region, and by appropriate points to the Diffserv network region, and by appropriate
provisioning within the Diffserv network region. To provide provisioning within the Diffserv network region. To provide
protection for Intserv traffic in Diffserv regions of the network, protection for Intserv traffic in Diffserv regions of the network,
we suggest that the DSCPs assigned to such traffic not overlap with we suggest that the DSCPs assigned to such traffic not overlap with
the DSCPs assigned to other traffic. the DSCPs assigned to other traffic.
7. Multicast 7. Multicast
The use of integrated services over Diffserv networks is The use of integrated services over Diffserv networks is
significantly more complex for multicast sessions than for unicast significantly more complex for multicast sessions than for unicast
sessions. With respect to a multicast connection, each participating sessions. With respect to a multicast connection, each participating
region has a single ingress router and zero, one or several egress region has a single ingress router and zero, one or several egress
routers. The difficulties of multicast are associated with Diffserv routers. The difficulties of multicast are associated with Diffserv
regions that contain several egress routers. (Support of multicast regions that contain several egress routers. (Support of multicast
functionality outside the Diffserv region is relatively functionality outside the Diffserv region is relatively
straightforward since every Intserv-capable router along the
multicast tree stores state for each flow.)
Bernet, ed. et al. 19 Bernet, ed. et al. 19
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straightforward since every Intserv-capable router along the
multicast tree stores state for each flow.)
Consider the following reference network: Consider the following reference network:
Non-Diffserv region 2 Non-Diffserv region 2
________ ________
/ \ / \
| | |---| | | |---|
________ _____________ | |-|Rx1| ________ _____________ | |-|Rx1|
/ \ / |--\ |---| | |---| / \ / |--\ |---| | |---|
/ \ / /|BR2\-----\ER2| / / \ / /|BR2\-----\ER2| /
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Non-Diffserv region 1 Diffserv region \ / Non-Diffserv region 1 Diffserv region \ /
\______/ \______/
Non-Diffserv region 3 Non-Diffserv region 3
Figure 2: Sample Multicast Network Configuration Figure 2: Sample Multicast Network Configuration
The reference network is similar to that of Figure 1. However, in The reference network is similar to that of Figure 1. However, in
Figure 2, copies of the packets sent by Tx are delivered to several Figure 2, copies of the packets sent by Tx are delivered to several
receivers outside of the Diffserv region, namely to Rx1 and Rx2. receivers outside of the Diffserv region, namely to Rx1 and Rx2.
Moreover, packets are copied within the Diffserv region in a _branch Moreover, packets are copied within the Diffserv region in a "branch
point_ router RR. In the reference network BR1 is the ingress router point" router RR. In the reference network BR1 is the ingress router
to the Diffserv region whereas BR2 and BR3 are the egress routers. to the Diffserv region whereas BR2 and BR3 are the egress routers.
In the simplest case the receivers, Rx1 and Rx2 in the reference In the simplest case the receivers, Rx1 and Rx2 in the reference
network, require identical reservations. The Diffserv framework [18] network, require identical reservations. The Diffserv framework [18]
supports service level specifications (SLS) from an ingress router supports service level specifications (SLS) from an ingress router
to one, some or all of the egress routers. This calls for a _one to to one, some or all of the egress routers. This calls for a "one to
many_ SLS within the Diffserv region, from BR1 to BR2 and BR3. Given many" SLS within the Diffserv region, from BR1 to BR2 and BR3. Given
that the SLS is granted by the Diffserv region, the ingress router that the SLS is granted by the Diffserv region, the ingress router
BR1, or perhaps an upstream node such as ER1, marks packets entering BR1, or perhaps an upstream node such as ER1, marks packets entering
the Diffserv region with the appropriate DSCP. The packets are the Diffserv region with the appropriate DSCP. The packets are
routed to the egresses of the Diffserv domain using the original routed to the egresses of the Diffserv domain using the original
multicast address. multicast address.
The two major problems, explained in the following, are associated The two major problems, explained in the following, are associated
with heterogeneous multicast trees containing branch points within with heterogeneous multicast trees containing branch points within
the Diffserv region, i.e. multicast trees where the level of the Diffserv region, i.e. multicast trees where the level of
resource requirement is not uniform among all receivers. An example resource requirement is not uniform among all receivers. An example
of such a scenario in the network of Figure 2 is the case where both of such a scenario in the network of Figure 2 is the case where both
Rx1 and Rx2 need to receive multicast data from Tx1 but only one of Rx1 and Rx2 need to receive multicast data from Tx1 but only one of
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Integrated Services Operation Over Diffserv Networks March, 2000
the receivers has requested a level of service above best effort. We the receivers has requested a level of service above best effort. We
consider such scenarios in the following paragraphs. consider such scenarios in the following paragraphs.
7.1 Remarking of packets in branch point routers 7.1 Remarking of packets in branch point routers
Bernet, ed. et al. 20
Integrated Services Operation Over Diffserv Networks June, 1999
In the above scenario, the packets that arrive at BR1 are marked In the above scenario, the packets that arrive at BR1 are marked
with an appropriate DSCP for the requested Intserv service and are with an appropriate DSCP for the requested Intserv service and are
sent to RR. Packets arriving at the branch point must be sent sent to RR. Packets arriving at the branch point must be sent
towards BR2 with the same DSCP otherwise the service to Rx1 is towards BR2 with the same DSCP otherwise the service to Rx1 is
degraded. However, the packets going from RR towards BR3 need not degraded. However, the packets going from RR towards BR3 need not
maintain the high assurance level anymore. They may be demoted to maintain the high assurance level anymore. They may be demoted to
best effort so that the QoS provided to other packets along this best effort so that the QoS provided to other packets along this
branch of the tree is not disrupted. Several problems can be branch of the tree is not disrupted. Several problems can be
observed in the given scenario: observed in the given scenario:
- In the Diffserv region, DSCP marking is done at edge routers - In the Diffserv region, DSCP marking is done at edge routers
(ingress), whereas a branch point router might be a core (ingress), whereas a branch point router might be a core
router, which does not mark packets. router, which does not mark packets.
- Being a core Diffserv router, RR classifies based on - Being a core Diffserv router, RR classifies based on
aggregate traffic streams (BA) _ as opposed to per flow (MF) aggregate traffic streams (BA), as opposed to per flow (MF)
classification. Hence, it does not necessarily have the classification. Hence, it does not necessarily have the
capability to distinguish those packets which belong to a capability to distinguish those packets which belong to a
specific multicast tree and require demotion from the other specific multicast tree and require demotion from the other
packets in the behavior aggregate, which carry the same DSCP. packets in the behavior aggregate, which carry the same DSCP.
- Since RR may be RSVP-unaware, it may not participate in the - Since RR may be RSVP-unaware, it may not participate in the
admission control process, and would thus not store any per- admission control process, and would thus not store any per-
flow state about the reservations for the multicast tree. flow state about the reservations for the multicast tree.
Hence, even if RR were able to perform MF classification and Hence, even if RR were able to perform MF classification and
DSCP remarking, it would not know enough about downstream DSCP remarking, it would not know enough about downstream
skipping to change at line 1154 skipping to change at line 1159
1. If some Intserv-capable routers are placed within the Diffserv 1. If some Intserv-capable routers are placed within the Diffserv
region, it might be possible to administer the network topology and region, it might be possible to administer the network topology and
routing parameters so as to ensure that branch points occur only routing parameters so as to ensure that branch points occur only
within such routers. These routers would support MF classification within such routers. These routers would support MF classification
and remarking and hold per-flow state for the heterogeneous and remarking and hold per-flow state for the heterogeneous
reservations for which they are the branch point. Note that in this reservations for which they are the branch point. Note that in this
case, branch point routers would have essentially the same case, branch point routers would have essentially the same
functionality as ingress routers of an RSVP-aware Diffserv domain. functionality as ingress routers of an RSVP-aware Diffserv domain.
2. Packets sent on the _non-reserved_ branch (from RR towards BR3) 2. Packets sent on the "non-reserved" branch (from RR towards BR3)
are marked with the _wrong_ DSCP; that is, they are not demoted to are marked with the "wrong" DSCP; that is, they are not demoted to
best effort but retain their DSCP. This in turn requires over best effort but retain their DSCP. This in turn requires over
reservation of resources along that link or runs the risk of reservation of resources along that link or runs the risk of
degrading service to packets that legitimately bear the same DSCP degrading service to packets that legitimately bear the same DSCP
along this path. However, it allows the Diffserv routers to remain along this path. However, it allows the Diffserv routers to remain
free of per-flow state. free of per-flow state.
Bernet, ed. et al. 21
Integrated Services Operation Over Diffserv Networks March, 2000
3. A combination of mechanism 1 and 2 may be an effective 3. A combination of mechanism 1 and 2 may be an effective
compromise. In this case, there are some Intserv-capable routers in compromise. In this case, there are some Intserv-capable routers in
the core of the network, but the network cannot be administered so the core of the network, but the network cannot be administered so
that ALL branch points fall at such routers. that ALL branch points fall at such routers.
Bernet, ed. et al. 21
Integrated Services Operation Over Diffserv Networks June, 1999
4. Administrators of Diffserv regions may decide not to enable 4. Administrators of Diffserv regions may decide not to enable
heterogeneous sub-trees in their domains. In the case of different heterogeneous sub-trees in their domains. In the case of different
downstream reservations, a ResvErr message would be sent according downstream reservations, a ResvErr message would be sent according
to the RSVP rules. This is similar to the approach taken for Intserv to the RSVP rules. This is similar to the approach taken for Intserv
over IEEE 802 Networks [2,5]. over IEEE 802 Networks [2,5].
5. In [3], a scheme was introduced whereby branch point routers in 5. In [3], a scheme was introduced whereby branch point routers in
the interior of the aggregation region (i.e. the Diffserv region) the interior of the aggregation region (i.e. the Diffserv region)
keep reduced state information regarding the reservations by using keep reduced state information regarding the reservations by using
measurement based admission control. Under this scheme, packets are measurement based admission control. Under this scheme, packets are
skipping to change at line 1217 skipping to change at line 1222
branches of a multicast tree, it may be possible to more closely branches of a multicast tree, it may be possible to more closely
approach the goal of allocating appropriate resources only where approach the goal of allocating appropriate resources only where
they are needed rather than overprovisioning or underprovisioning they are needed rather than overprovisioning or underprovisioning
along certain branches of a tree. This is essentially the approach along certain branches of a tree. This is essentially the approach
described in [15]. described in [15].
8. Security Considerations 8. Security Considerations
8.1 General RSVP Security 8.1 General RSVP Security
We are proposing that RSVP signaling be used to obtain resources in
both Diffserv and non-Diffserv regions of a network. Therefore, all
RSVP security considerations apply [9]. In addition, network
Bernet, ed. et al. 22 Bernet, ed. et al. 22
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
We are proposing that RSVP signaling be used to obtain resources in
both Diffserv and non-Diffserv regions of a network. Therefore, all
RSVP security considerations apply [9]. In addition, network
administrators are expected to protect network resources by administrators are expected to protect network resources by
configuring secure policers at interfaces with untrusted customers. configuring secure policers at interfaces with untrusted customers.
8.2 Host Marking 8.2 Host Marking
Though it does not mandate host marking of the DSCP, our proposal Though it does not mandate host marking of the DSCP, our proposal
does allow it. Allowing hosts to set the DSCP directly may alarm does allow it. Allowing hosts to set the DSCP directly may alarm
network administrators. The obvious concern is that hosts may network administrators. The obvious concern is that hosts may
attempt to 'steal' resources. In fact, hosts may attempt to exceed attempt to "steal" resources. In fact, hosts may attempt to exceed
negotiated capacity in Diffserv network regions at a particular negotiated capacity in Diffserv network regions at a particular
service level regardless of whether they invoke this service level service level regardless of whether they invoke this service level
directly (by setting the DSCP) or indirectly (by submitting traffic directly (by setting the DSCP) or indirectly (by submitting traffic
that classifies in an intermediate marking router to a particular that classifies in an intermediate marking router to a particular
DSCP). DSCP).
In either case, it will generally be necessary for each Diffserv In either case, it will generally be necessary for each Diffserv
network region to protect its resources by policing to assure that network region to protect its resources by policing to assure that
customers do not use more resources than they are entitled to, at customers do not use more resources than they are entitled to, at
each service level (DSCP). The exception to this rule is when the each service level (DSCP). The exception to this rule is when the
skipping to change at line 1268 skipping to change at line 1272
responsibility to the edges of the network, where it scales better responsibility to the edges of the network, where it scales better
and provides other benefits described in Section 3.3.1. The larger and provides other benefits described in Section 3.3.1. The larger
Diffserv network regions are thus focused on the task of protecting Diffserv network regions are thus focused on the task of protecting
their networks, while the Intserv-capable nodes are focused on the their networks, while the Intserv-capable nodes are focused on the
task of shaping and policing their own traffic to be in compliance task of shaping and policing their own traffic to be in compliance
with their negotiated Intserv parameters. with their negotiated Intserv parameters.
9. Acknowledgments 9. Acknowledgments
Authors thank the following individuals for their comments that led Authors thank the following individuals for their comments that led
to improvements to the previous version(s) of this draft: David to improvements to the previous version(s) of this document: David
Oran, Andy Veitch, Curtis Villamizer, Walter Weiss, Francois le Oran, Andy Veitch, Curtis Villamizer, Walter Weiss, Francois le
Faucheur and Russell White. Faucheur and Russell White.
Many of the ideas in this document have been previously discussed in Many of the ideas in this document have been previously discussed in
the original Intserv architecture document [10]. the original Intserv architecture document [10].
10. References
Bernet, ed. et al. 23 Bernet, ed. et al. 23
Integrated Services Operation Over Diffserv Networks June, 1999 Integrated Services Operation Over Diffserv Networks March, 2000
10. References
[1] Braden, R., Zhang, L., Berson, S., Herzog, S. and Jamin, S., [1] Braden, R., Zhang, L., Berson, S., Herzog, S. and Jamin, S.,
"Resource Reservation Protocol (RSVP) Version 1 Functional "Resource Reservation Protocol (RSVP) Version 1 Functional
Specification", RFC 2205, Proposed Standard, September 1997 Specification", RFC 2205, Proposed Standard, September 1997
[2] Yavatkar, R., Hoffman, D., Bernet, Y., Baker, F. and Speer, M., [2] Yavatkar, R., Hoffman, D., Bernet, Y., Baker, F. and Speer, M.,
"SBM (Subnet Bandwidth Manager): A Protocol For RSVP-based "SBM (Subnet Bandwidth Manager): A Protocol For RSVP-based
Admission Control Over IEEE 802 Style Networks", Internet Draft, Admission Control Over IEEE 802 Style Networks", Internet Draft,
[3] Berson, S. and Vincent, R., "Aggregation of Internet Integrated [3] Berson, S. and Vincent, R., "Aggregation of Internet Integrated
Services State", Internet Draft, draft-berson-rsvp-aggregation- Services State", Internet Draft, draft-berson-rsvp-aggregation-
00.txt, August 1998. 00.txt, August 1998.
[4] Nichols, K., Jacobson, V. and Zhang, L., "A Two-bit [4] Nichols, K., Jacobson, V. and Zhang, L., "A Two-bit
Differentiated Services Architecture for the Internet", RFC Differentiated Services Architecture for the Internet", RFC
2638, July 1999. 2638, July 1999.
[5] Seaman, M., Smith, A., Crawley, E., and Wroclawski, J., [5] Seaman, M., Smith, A., Crawley, E., and Wroclawski, J.,
"Integrated Service Mappings on IEEE 802 Networks", Internet "Integrated Service Mappings on IEEE 802 Networks", Internet
[6] Guerin, R., Blake, S. and Herzog, S., "Aggregating RSVP based [6] Guerin, R., Blake, S. and Herzog, S., "Aggregating RSVP based
QoS QoS Requests", Internet Draft, draft-guerin-aggreg-rsvp-00.txt,
Requests", Internet Draft, draft-guerin-aggreg-rsvp-00.txt,
November 1997. November 1997.
[7] Nichols, Kathleen, et al., "Definition of the Differentiated [7] Nichols, Kathleen, et al., "Definition of the Differentiated
Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC
2474, December 1998. 2474, December 1998.
[8] Blake, S., et al., "An Architecture for Differentiated [8] Blake, S., et al., "An Architecture for Differentiated
Services." RFC 2475, December 1998. Services." RFC 2475, December 1998.
[9] Baker, F., "RSVP Cryptographic Authentication", Internet Draft, [9] Baker, F., "RSVP Cryptographic Authentication", Internet Draft,
skipping to change at line 1324 skipping to change at line 1327
the Internet Architecture: an Overview", Internet RFC 1633, the Internet Architecture: an Overview", Internet RFC 1633,
[11] Garrett, M. W., and Borden, M., "Interoperation of Controlled- [11] Garrett, M. W., and Borden, M., "Interoperation of Controlled-
Load Service and Guaranteed Service with ATM", RFC2381, August Load Service and Guaranteed Service with ATM", RFC2381, August
1998. 1998.
[12] Weiss, Walter, Private communication, November 1998. [12] Weiss, Walter, Private communication, November 1998.
[13] Kent, S., Atkinson, R., "Security Architecture for the Internet [13] Kent, S., Atkinson, R., "Security Architecture for the Internet
Protocol", RFC 2401, November 1998. Protocol", RFC 2401, November 1998.
Bernet, ed. et al. 24
Integrated Services Operation Over Diffserv Networks March, 2000
[14] Bernet, Y., "Usage and Format of the DCLASS Object with RSVP [14] Bernet, Y., "Usage and Format of the DCLASS Object with RSVP
Signaling", Internet Draft, draft-issll-dclass-00.txt, August Signaling", Internet Draft, draft-issll-dclass-00.txt, August
1999. 1999.
Bernet, ed. et al. 24
Integrated Services Operation Over Diffserv Networks June, 1999
[15] Baker, F., Iturralde, C., le Faucheur, F., and Davie, B. "RSVP [15] Baker, F., Iturralde, C., le Faucheur, F., and Davie, B. "RSVP
Reservation Aggregation", Internet Draft, draft-ietf-issll- Reservation Aggregation", Internet Draft, draft-ietf-issll-
aggregation-00.txt, September 1999. aggregation-00.txt, September 1999.
[16] Terzis, A., Krawczyk, J., Wroclawski, J., Zhang, L., "RSVP [16] Terzis, A., Krawczyk, J., Wroclawski, J., Zhang, L., "RSVP
Operation Over IP Tunnels", Internet Draft, draft-ietf-rsvp- Operation Over IP Tunnels", Internet Draft, draft-ietf-rsvp-
tunnel-04.txt, May 1999. tunnel-04.txt, May 1999.
[17] Boyle, J., Cohen, R., Durham, D., Herzog, S., Rajan, D., and [17] Boyle, J., Cohen, R., Durham, D., Herzog, S., Rajan, D., and
Sastry, A., _COPS Usage for RSVP_, Internet Draft, draft-ietf- Sastry, A., "COPS Usage for RSVP", Internet Draft, draft-ietf-
rap-cops-rsvp-05.txt, June 1999. rap-cops-rsvp-05.txt, June 1999.
[18] Bernet, Y., et al., _A Framework for Differentiated Services_, [18] Bernet, Y., et al., "A Framework for Differentiated Services",
Internet draft, draft-ietf-diffserv-framework-02.txt, February Internet draft, draft-ietf-diffserv-framework-02.txt, February
1999. 1999.
[19] Jacobson Van, "Differentiated Services Architecture", talk in
the Int-Serv WG at the Munich IETF, August 1997.
[20] Jacobson, V., Nichols K., and Zhang, L. "A Two-bit
Differentiated Services Architecture for the Internet",
RFC 2638, June 1999.
[21] First Internet2 bandwidth broker operability event
http://www.merit.edu/internet/working.groups/i2-qbone-bb/
inter-op/index.htm
11. Author's Addresses: 11. Author's Addresses:
Yoram Bernet Yoram Bernet
Microsoft Microsoft
One Microsoft Way, Redmond, WA 98052 One Microsoft Way, Redmond, WA 98052
Phone: (425) 936-9568 Phone: (425) 936-9568
Email: yoramb@microsoft.com Email: yoramb@microsoft.com
Raj Yavatkar Raj Yavatkar
Intel Corporation Intel Corporation
JF3-206 2111 NE 25th. Avenue, Hillsboro, OR 97124 JF3-448 2111 NE 25th. Avenue, Hillsboro, OR 97124
Phone: (503) 264-9077 Phone: (503) 264-9077
Email: raj.yavatkar@intel.com Email: raj.yavatkar@intel.com
Peter Ford Peter Ford
Microsoft Microsoft
One Microsoft Way, Redmond, WA 98052 One Microsoft Way, Redmond, WA 98052
Phone: (425) 703-2032 Phone: (425) 703-2032
Email: peterf@microsoft.com Email: peterf@microsoft.com
Fred Baker Fred Baker
Bernet, ed. et al. 25
Integrated Services Operation Over Diffserv Networks March, 2000
Cisco Systems Cisco Systems
519 Lado Drive, Santa Barbara, CA 93111 519 Lado Drive, Santa Barbara, CA 93111
Phone: (408) 526-4257 Phone: (408) 526-4257
Email: fred@cisco.com Email: fred@cisco.com
Lixia Zhang Lixia Zhang
UCLA UCLA
4531G Boelter Hall Los Angeles, CA 90095 4531G Boelter Hall Los Angeles, CA 90095
Phone: +1 310-825-2695 Phone: (310) 825-2695
Email: lixia@cs.ucla.edu Email: lixia@cs.ucla.edu
Michael Speer Michael Speer
Sun Microsystems Sun Microsystems
901 San Antonio Road UMPK15-215 Palo Alto, CA 94303 901 San Antonio Road UMPK15-215 Palo Alto, CA 94303
Phone: (650)786-6368
Bernet, ed. et al. 25
Integrated Services Operation Over Diffserv Networks June, 1999
Phone: +1 650-786-6368
Email: speer@Eng.Sun.COM Email: speer@Eng.Sun.COM
Bob Braden Bob Braden
USC Information Sciences Institute USC Information Sciences Institute
4676 Admiralty Way Marina del Rey, CA 90292-6695 4676 Admiralty Way Marina del Rey, CA 90292-6695
Phone: 310-822-1511 Phone: (310) 822-1511
Email: braden@isi.edu Email: braden@isi.edu
Bruce Davie Bruce Davie
Cisco Systems Cisco Systems
250 Apollo Drive, Chelmsford, MA 01824 250 Apollo Drive, Chelmsford, MA 01824
Phone: (978)-244-8000 Phone: (978) 244-8000
Email: bsd@cisco.com Email: bsd@cisco.com
Eyal Felstaine Eyal Felstaine
Allot Communications Dept. of Computer Science
5 Hanagar St. Technion, IIT
Neve Ne'eman B Hod- Hasharon. 32000 Haifa, Israel
45800 Israel. Phone: +972-50-747672
Phone: +972-9-7443676/ext 202 Email: eyalfe@cs.technion.ac.il
Email: efelstaine@allot.com
John Wroclawski John Wroclawski
MIT Laboratory for Computer Science MIT Laboratory for Computer Science
545 Technology Sq. 545 Technology Sq.
Cambridge, MA 02139 Cambridge, MA 02139
Phone: 617-253-7885 Phone: (617) 253-7885
E-mail: jtw@lcs.mit.edu E-mail: jtw@lcs.mit.edu
12. Full Copyright Statement 12. Full Copyright Statement
Copyright (C) The Internet Society (1999). All Rights Reserved. Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
Bernet, ed. et al. 26
Integrated Services Operation Over Diffserv Networks March, 2000
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than followed, or as required to translate it into languages other than
English. English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
Bernet, ed. et al. 26
Integrated Services Operation Over Diffserv Networks June, 1999
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
This draft expires March, 2000 This draft expires September, 2000
Bernet, ed. et al. 27 Bernet, ed. et al. 27
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