draft-ietf-tcpm-experimental-options-06.txt   rfc6994.txt 
TCPM Working Group J. Touch
Internet Draft USC/ISI
Intended status: Proposed Standard June 4, 2013
Expires: December 2013
Shared Use of Experimental TCP Options Internet Engineering Task Force (IETF) J. Touch
draft-ietf-tcpm-experimental-options-06.txt Request for Comments: 6994 USC/ISI
Category: Standards Track August 2013
ISSN: 2070-1721
Status of this Memo Shared Use of Experimental TCP Options
This Internet-Draft is submitted in full conformance with the Abstract
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document describes how the experimental TCP option codepoints
Task Force (IETF), its areas, and its working groups. Note that can concurrently support multiple TCP extensions, even within the
other groups may also distribute working documents as Internet- same connection, using a new IANA TCP experiment identifier. This
Drafts. approach is robust to experiments that are not registered and to
those that do not use this sharing mechanism. It is recommended for
all new TCP options that use these codepoints.
Internet-Drafts are draft documents valid for a maximum of six Status of This Memo
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at This is an Internet Standards Track document.
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at This document is a product of the Internet Engineering Task Force
http://www.ietf.org/shadow.html (IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on December 4, 2013. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6994.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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warranty as described in the Simplified BSD License. described in the Simplified BSD License.
Abstract
This document describes how the experimental TCP option codepoints
can concurrently support multiple TCP extensions, even within the
same connection. It uses a new IANA TCP experiment identifier, and
is also robust to experiments that are not registered and those that
do not use this sharing mechanism. It is recommended for all new TCP
options that use these codepoints.
Table of Contents Table of Contents
1. Introduction...................................................2 1. Introduction ....................................................2
2. Conventions used in this document..............................4 2. Conventions Used in This Document ...............................3
3. TCP Experimental Option Structure..............................4 3. TCP Experimental Option Structure ...............................4
3.1. Selecting an ExID.........................................6 3.1. Selecting an ExID ..........................................5
3.2. Impact on TCP Option Processing...........................7 3.2. Impact on TCP Option Processing ............................6
4. Reducing the Impact of False Positives.........................7 4. Reducing the Impact of False Positives ..........................7
5. Migration to Assigned Options..................................8 5. Migration to Assigned Options ...................................7
6. Rationale......................................................8 6. Rationale .......................................................8
7. Security Considerations........................................9 7. Security Considerations .........................................9
8. IANA Considerations............................................9 8. IANA Considerations .............................................9
9. References....................................................10 9. References .....................................................10
9.1. Normative References.....................................10 9.1. Normative References ......................................10
9.2. Informative References...................................10 9.2. Informative References ....................................10
10. Acknowledgments..............................................12 10. Acknowledgments ...............................................11
1. Introduction 1. Introduction
TCP includes options to enable new protocol capabilities that can be TCP includes options to enable new protocol capabilities that can be
activated only where needed and supported [RFC793]. The space for activated only where needed and supported [RFC793]. The space for
identifying such options is small - 256 values, of which 30 are identifying such options is small -- 256 values, of which 30 are
assigned at the time this document was published [IANA]. Two of assigned at the time of this document's publication [IANA]. Two of
these codepoints are allocated to support experiments (253, 254) these codepoints (253, 254) are allocated to support experiments
[RFC4727]. These values are intended for testing purposes or anytime [RFC4727]. These values are intended for testing purposes or for use
an assigned codepoint is either not warranted or available, e.g., when an assigned codepoint is either not warranted or available,
based on the maturity status of the defined capability (i.e., e.g., based on the maturity status of the defined capability (i.e.,
Experimental or Informational, rather than Standards Track). Experimental or Informational, rather than Standards Track).
The term "experimental TCP options" refers here to options that use Here, the term "experimental TCP options" refers to options that use
the TCP experimental option codepoints [RFC4727]. Such experiments the TCP experimental option codepoints [RFC4727]. Such experiments
can be described in any type of RFC - Experimental, Informational, can be described in an RFC of any status (e.g., Experimental,
etc., and are intended to be used both in controlled environments Informational, etc.) and are intended to be used in controlled
and in are allowed in public deployments (when not enabled as environments and are allowed in public deployments (when not enabled
default) [RFC3692]. Nothing prohibits deploying multiple experiments as default [RFC3692]). Nothing prohibits the deployment of multiple
in the same environment - controlled or public. Further, some experiments in the same environment -- controlled or public.
protocols are specified in Experimental or Informational RFCs, which Further, some protocols are specified in Experimental or
either include parameters or design choices not yet understood or Informational RFCs, which either include parameters or design choices
which might not be widely deployed [RFC2026]. TCP options in such not yet understood or which might not be widely deployed [RFC2026].
RFCs are typically not eligible for assigned TCP option codepoints Typically, these TCP options are not eligible to receive assigned
[RFC2780], and so there is a need to share use of the experimental codepoints [RFC2780], so they need a way to share their use of the
option codepoints. experimental codepoints.
There is currently no mechanism to support shared use of the TCP There is currently no mechanism to support shared use of the TCP
experimental option codepoints, either by different experiments on experimental option codepoints, either by different experiments on
different connections, or for more than two experimental options in different connections or for more than two experimental options in
the same connection. Experimental options 253 and 254 are already the same connection. Experimental options 253 and 254 are already
deployed in operational code to support an early version of TCP deployed in operational code to support an early version of TCP
authentication. Option 253 is also documented for the experimental authentication. Option 253 is also documented for the experimental
TCP Cookie Transaction option [RFC6013]. This shared use results in TCP Cookie Transaction option [RFC6013]. This shared use results in
collisions in which a single codepoint can appear multiple times in collisions in which a single codepoint can appear multiple times in a
a single TCP segment and for which each use is ambiguous. single TCP segment and for which each use is ambiguous.
Other codepoints have been used without assignment (known as Other codepoints have been used without assignment (known as
"squatting"), notably 31-32 (TCP cookie transactions, as originally "squatting"), notably 31-32 (TCP cookie transactions, as originally
distributed and in its API doc) and 76-78 (tcpcrypt) [Bi11][Si11]. distributed and in its API doc) and 76-78 (tcpcrypt) [Bi11] [Si11].
Commercial products reportedly also use unassigned options 33, 69- Commercial products reportedly also use unassigned options 33, 69-70,
70, and 76-78 as well. Even though these uses are unauthorized, they and 76-78. Even though these uses are unauthorized, they currently
currently impact legitimate assignees. impact legitimate assignees.
Both such misuses (squatting on both experimental and assigned Both such misuses (squatting on both experimental and assigned
codepoints) are expected to continue, but there are several codepoints) are expected to continue, but there are several
approaches which can alleviate the impact on cooperating protocol approaches that can alleviate the impact on cooperating protocol
designers. One proposal relaxes the requirements for assignment of designers. One proposal relaxes the requirements for assignment of
TCP options, allowing them to be assigned more readily for protocols TCP options, allowing them to be assigned more readily for protocols
that have not been standardized through the IETF process [RFC5226]. that have not been standardized through the IETF process [RFC5226].
Another proposal assigns a larger pool to the TCP experiment option Another proposal assigns a larger pool to the TCP experiment option
codepoints and manages their sharing through IANA coordination codepoints and manages their sharing through IANA coordination
[Ed11]. [Ed11].
The approach proposed in this document does not require additional The approach proposed in this document does not require additional
TCP option codepoints, and is robust to those who choose either not TCP option codepoints and is robust to those who choose either not to
to support it or not to register their experiments. The solution support it or not to register their experiments. The solution adds a
adds a field to the structure of the experimental TCP option. This field to the structure of the experimental TCP option. This field is
field is populated with an "experiment identifier" (ExID) defined as populated with an "experiment identifier" (ExID) defined as part of a
part of a specific option experiment. The ExID helps reduce the specific option experiment. The ExID helps reduce the probability of
probability of a collision of independent experimental uses of the a collision of independent experimental uses of the same option
same option codepoint, both for those who follow this document codepoint, both for those who follow this document (using registered
(using registered ExIDs) and those who do not (squatters who either ExIDs) and those who do not (squatters who either ignore this
ignore this extension or do not register their ExIDs). extension or do not register their ExIDs).
The solution proposed in this document is recommended for all new The solution proposed in this document is recommended for all new
protocols that use TCP experimental option codepoints. The protocols that use TCP experimental option codepoints. The
techniques used here may also help share other experimental techniques described here may also enable shared use of other
codepoints, but that issue is out of scope for this document. experimental codepoints, but that issue is out of scope for this
document.
2. Conventions used in this document 2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
In this document, these words will appear with that interpretation In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be only when in ALL CAPS. Lowercase uses of these words are not to be
interpreted as carrying RFC-2119 significance. interpreted as carrying RFC 2119 significance.
In this document, the characters ">>" preceding an indented line(s) In this document, the characters ">>" preceding an indented line(s)
indicates a compliance requirement statement using the key words indicates a compliance requirement statement using the key words
listed above. This convention aids reviewers in quickly identifying listed above. This convention aids reviewers in quickly identifying
or finding the explicit compliance requirements of this RFC. or finding the explicit compliance requirements of this RFC.
3. TCP Experimental Option Structure 3. TCP Experimental Option Structure
TCP options have the current common structure [RFC793], in which the TCP options have the current common structure [RFC793], in which the
first byte is the codepoint (Kind) and the second byte is the length first byte is the codepoint (Kind) and the second byte is the length
of the option in bytes (Length): of the option in bytes (Length):
0 1 2 3 0 1 2 3
01234567 89012345 67890123 45678901 01234567 89012345 67890123 45678901
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| Kind | Length | ... | | Kind | Length | ... |
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| ... | ...
+-------- +--------
Figure 1 TCP Option Structure [RFC793] Figure 1. TCP Option Structure [RFC793]
This document extends the option structure for experimental This document extends the option structure for experimental
codepoints (253, 254) with an experiment identifier (ExID), which is codepoints (253, 254) with an experiment identifier (ExID), which is
either 2 or 4 bytes in length. The ExID is used to differentiate either 2 or 4 bytes in length. The ExID is used to differentiate
different experiments, and is the first field after the Kind and experiments and is the first field after Kind and Length, as follows:
Length, as follows:
0 1 2 3 0 1 2 3
01234567 89012345 67890123 45678901 01234567 89012345 67890123 45678901
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| Kind | Length | ExID | | Kind | Length | ExID |
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| option contents... | option contents...
+--------+--------+--------+--- +--------+--------+--------+---
Figure 2 TCP Experimental Option with a 16-bit ExID Figure 2. TCP Experimental Option with a 16-bit ExID
0 1 2 3 0 1 2 3
01234567 89012345 67890123 45678901 01234567 89012345 67890123 45678901
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| Kind | Length | ExID | | Kind | Length | ExID |
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| ExID (con't) | option contents... | ExID (con't) | option contents...
+--------+--------+--------+--- +--------+--------+--------+---
Figure 3 TCP Experimental Option with a 32-bit ExID Figure 3. TCP Experimental Option with a 32-bit ExID
This mechanism is encouraged for all TCP options that are not yet This mechanism is encouraged for all TCP options that are not yet
eligible for assigned codepoints: eligible for assigned codepoints:
>> Protocols requiring new TCP option codepoints that are not >> Protocols requiring new TCP option codepoints that are not
eligible for assigned values SHOULD use the existing TCP eligible for assigned values SHOULD use the existing TCP
experimental option codepoints (253, 254) with ExIDs as described in experimental option codepoints (253, 254) with ExIDs as described
this document. in this document.
This mechanism is encouraged for all TCP options using the current This mechanism is encouraged for all TCP options using the current
experimental codepoints in controlled environments: experimental codepoints in controlled environments:
>> All protocols using the TCP experimental option codepoints (253, >> All protocols using the TCP experimental option codepoints (253,
254), even those deployed in controlled environments, SHOULD use 254), even those deployed in controlled environments, SHOULD use
ExIDs as described in this document. ExIDs as described in this document.
This mechanism is required for all TCP options using the current This mechanism is required for all TCP options using the current
experimental codepoints that are publicly deployed, whether enabled experimental codepoints that are publicly deployed, whether enabled
by default or not: by default or not:
>> All protocols using the TCP experimental option codepoints (253, >> All protocols using the TCP experimental option codepoints (253,
254) that are deployed outside controlled environments, such as in 254) that are deployed outside controlled environments, such as in
the public Internet, MUST use ExIDs as described in this document. the public Internet, MUST use ExIDs as described in this document.
Once a TCP option uses the mechanism in this document, registration Once a TCP option uses the mechanism in this document, registration
of the ExID with IANA is required: of the ExID with IANA is required:
>> All protocols using ExIDs as described in this document MUST >> All protocols using ExIDs as described in this document MUST
register those ExIDs with IANA. register those ExIDs with IANA.
Applicants register their desired ExID by contacting IANA [IANA]. Applicants register their desired ExID by contacting IANA [IANA].
3.1. Selecting an ExID 3.1. Selecting an ExID
ExIDs are selected at design time, when the protocol designer first ExIDs are selected at design time, when the protocol designer first
implements or specifies the experimental option. ExIDs can be either implements or specifies the experimental option. ExIDs can be either
16-bits or 32-bits. In both cases, the value is stored in the header 16 bits or 32 bits. In both cases, the value is stored in the header
in network-standard (big-endian) byte order. ExIDs combine in network-standard (big-endian) byte order. ExIDs combine
properties of IANA registered codepoints with "magic numbers". properties of IANA registered codepoints with "magic numbers".
>> All ExIDs MUST be either 16-bits or 32-bits long. >> All ExIDs MUST be either 16 bits or 32 bits long.
Use of the ExID, whether 16-bit or 32-bit, helps reduce the Use of the ExID, whether 16 bit or 32 bit, helps reduce the
probability of a false positive collision with those who either do probability of a false positive collision with those who either do
not register their experiment or who do not implement this not register their experiment or who do not implement this mechanism.
mechanism.
In order to conserve TCP option space, either for use within a In order to conserve TCP option space, either for use within a
specific option or to be available for other options: specific option or to be available for other options:
>> Options implementing the mechanism of this document SHOULD >> Options implementing the mechanism of this document SHOULD use
use 16-bit ExIDs except where explicitly motivating the need for 32- 16-bit ExIDs, except where explicitly motivating the need for
bit ExIDs, e.g., to avoid false positives or maintain alignment with 32-bit ExIDs, e.g., to avoid false positives or maintain alignment
an expected future assigned codepoint. with an expected future assigned codepoint.
ExIDs are registered with IANA using "first-come, first-served" ExIDs are registered with IANA using "first come, first served"
priority based on the first two bytes. Those two bytes are thus (FCFS) priority based on the first two bytes. Those two bytes are
sufficient to interpret which experimental option is contained in thus sufficient to interpret which experimental option is contained
the option field. in the option field.
>> All ExIDs MUST be unique based on their first 16 bits. >> All ExIDs MUST be unique based on their first 16 bits.
The second two bytes serve as a "magic number". A magic number is a The second two bytes serve as a "magic number". A magic number is a
self-selected codepoint whose primary value is its unlikely self-selected codepoint whose primary value is its unlikely collision
collision with values selected by others. Magic numbers are used in with values selected by others. Magic numbers are used in other
other protocols, e.g., BOOTP [RFC951] and DHCP [RFC2131]. protocols, e.g., bootstrap protocol (BOOTP) [RFC951] and DHCP
[RFC2131].
Using the additional magic number bytes helps the option contents Using the additional magic number bytes helps the option contents
have the same byte alignment in the TCP header as they would have if have the same byte alignment in the TCP header as they would have if
(or when) a conventional (non-experiment) TCP option codepoint is (or when) a conventional (non-experiment) TCP option codepoint is
assigned. Use of the same alignment reduces the potential for assigned. Use of the same alignment reduces the potential for
implementation errors, especially in using the same word-alignment implementation errors, especially in using the same word-alignment
padding, if the same software is later modified to use a padding, if the same software is later modified to use a conventional
conventional codepoint. Use of the longer, 32-bit ExID further codepoint. Use of the longer, 32-bit ExID further decreases the
decreases the probability of such a false positive compared to those probability of such a false positive compared to those using shorter,
using shorter, 16-bit ExIDs. 16-bit ExIDs.
Use of the ExID does consume TCP option space but enables concurrent Use of the ExID does consume TCP option space but enables concurrent
use of the experimental codepoints and provides protection against use of the experimental codepoints and provides protection against
false positives, leaving less space for other options (including false positives, leaving less space for other options (including
other experiments). Use of the longer, 32-bit ExID consumes more other experiments). Use of the longer, 32-bit ExID consumes more
space, but provides more protection against false positives.S space, but provides more protection against false positives.
3.2. Impact on TCP Option Processing 3.2. Impact on TCP Option Processing
The ExID number is considered part of the TCP option, not the TCP The ExID number is considered part of the TCP option, not the TCP
option header. The presence of the ExID increases the effective option header. The presence of the ExID increases the effective
option Length field by the size of the ExID. The presence of this option Length field by the size of the ExID. The presence of this
ExID is thus transparent to implementations that do not support TCP ExID is thus transparent to implementations that do not support TCP
options where it is used. options.
During TCP processing, ExIDs in experimental options are matched During TCP processing, ExIDs in experimental options are matched
against the ExIDs for each implemented protocol. The remainder of against the ExIDs for each implemented protocol. The remainder of
the option is specified by the particular experimental protocol. the option is specified by the particular experimental protocol.
>> Experimental options that have ExIDs that do not match >> Experimental options with ExIDs that do not match implemented
implemented protocols MUST be ignored. protocols MUST be ignored.
The ExID mechanism must be coordinated during connection The ExID mechanism must be coordinated during connection
establishment, just as with any TCP option. establishment, just as with any TCP option.
>> TCP ExID, if used in any TCP segment of a connection, MUST be >> TCP ExID, if used in any TCP segment of a connection, MUST be
present in TCP SYN segments of that connection. present in TCP SYN segments of that connection.
>> TCP experimental option ExIDS, if used in any TCP segment of a >> TCP experimental option ExIDs, if used in any TCP segment of a
connection, SHOULD be used in all TCP segments of that connection in connection, SHOULD be used in all TCP segments of that connection
which any experimental option is present. in which any experimental option is present.
Use of an ExID uses additional space in the TCP header and requires Use of an ExID uses additional space in the TCP header and requires
additional protocol processing by experimental protocols. Because additional protocol processing by experimental protocols. Because
these are experiments, neither consideration is a substantial these are experiments, neither consideration is a substantial
impediment; a finalized protocol can avoid both issues with the impediment; a finalized protocol can avoid both issues with the
assignment of a dedicated option codepoint later. assignment of a dedicated option codepoint later.
4. Reducing the Impact of False Positives 4. Reducing the Impact of False Positives
False positives occur where the registered ExID of an experiment False positives occur where the registered ExID of an experiment
matches the value of an option that does not use ExIDs. Such matches the value of an option that does not use ExIDs. Such
collisions can cause an option to be interpreted by the incorrect collisions can cause an option to be interpreted by the incorrect
processing routine. Use of checksums or signatures may help an processing routine. Use of checksums or signatures may help an
experiment use the shorter ExID while reducing the corresponding experiment use the shorter ExID while reducing the corresponding
increased potential for false positives. increased potential for false positives.
>> Experiments that are not robust to ExID false positives SHOULD >> Experiments that are not robust to ExID false positives SHOULD
implement other detection measures, such as checksums or minimal implement other detection measures, such as checksums or minimal
digital signatures over the experimental options they support. digital signatures over the experimental options they support.
5. Migration to Assigned Options 5. Migration to Assigned Options
Some experiments may transition from experiment, and become eligible Some experiments may transition away from being experimental and
for an assigned TCP option codepoint. This document does not become eligible for an assigned TCP option codepoint. This document
recommend a specific migration plan to transition from use of the does not recommend a specific migration plan to transition from use
experimental TCP options/ExIDs to use of an assigned codepoint. of the experimental TCP options/ExIDs to use of an assigned
codepoint.
However, once an assigned codepoint is allocated, use of an ExID However, once an assigned codepoint is allocated, use of an ExID
represents unnecessary overhead. As a result: represents unnecessary overhead. As a result:
>> Once a TCP option codepoint is assigned to a protocol, that >> Once a TCP option codepoint is assigned to a protocol, that
protocol SHOULD NOT continue to use an ExID as part of that assigned protocol SHOULD NOT continue to use an ExID as part of that
codepoint. assigned codepoint.
This document does not recommend whether or how an implementation of This document does not recommend whether or how an implementation of
an assigned codepoint can be backward-compatible with use of the an assigned codepoint can be backward compatible with use of the
experimental codepoint/ExID. experimental codepoint/ExID.
However, some implementers may be tempted to include both the However, some implementers may be tempted to include both the
experimental and assigned codepoint in the same segment, e.g., in a experimental and assigned codepoint in the same segment, e.g., in a
SYN to support backward-compatibility during connection SYN to support backward compatibility during connection
establishment. This is a poor use limited resources and so to ensure establishment. This is a poor use of limited resources; so, to
conservation of the TCP option space: ensure conservation of the TCP option space:
>> A TCP segment MUST NOT contain both an assigned TCP option >> A TCP segment MUST NOT contain both an assigned TCP option
codepoint and a TCP experimental option codepoint for the same codepoint and a TCP experimental option codepoint for the same
protocol. protocol.
Instead, a TCP that intends backward compatibility might send Instead, a TCP that intends backward compatibility might send
multiple SYNs with alternates of the same option and discard all but multiple SYNs with alternates of the same option and discard all but
the most desired successful connection. Although this approach may the most desired successful connection. Although this approach may
resolve more slowly or require additional effort at the endpoints, resolve more slowly or require additional effort at the endpoints, it
it is preferable to excessively consuming TCP option space. is preferable to excessively consuming TCP option space.
6. Rationale 6. Rationale
The ExIDs described in this document combine properties of IANA The ExIDs described in this document combine properties of IANA
first-come/first-served (FCFS) registered values with magic numbers. FCFS-registered values with magic numbers. Although IANA FCFS
Although IANA FCFS registries are common, so too are those who registries are common, so too are those who either fail to register
either fail to register or who 'squat' by deliberately using or who 'squat' by deliberately using codepoints that are assigned to
codepoints that are assigned to others. The approach in this others. The approach in this document is intended to recognize this
document is intended to recognize this reality and be more robust to reality and be more robust to its consequences than would be a
its consequences than would be a conventional IANA FCFS registry. conventional IANA FCFS registry.
Existing ID spaces were considered as ExIDs in the development of Existing ID spaces were considered as ExIDs in the development of
this mechanism, including IEEE Organizationally Unique Identifier this mechanism, including IEEE Organizationally Unique Identifier
(OUI) and IANA Private Enterprise Numbers (PENs) [802] [OUI] (OUI) and IANA Private Enterprise Numbers (PENs) [IEEE802] [OUI]
[RFC1155]. [RFC1155].
OUIs are 24-bit identifiers that are combined with 24 to 40-bits of OUIs are 24-bit identifiers that are combined with 24 to 40 bits of
privately-assigned space to create identifiers that commonly privately assigned space to create identifiers that are commonly
assigned to a unique piece of hardware. OUIs are already longer than assigned to a unique piece of hardware. OUIs are already longer than
the smaller ExID value, and obtaining an OUI is costly (currently the smaller ExID value, and obtaining an OUI is costly (currently
$1,885.00 USD). An OUI could be obtained for each experiment, but $1,885.00 USD). An OUI could be obtained for each experiment, but
this could be considered expensive. An OUI already assigned to an this could be considered expensive. An OUI already assigned to an
organization could be shared if extended (to support multiple organization could be shared if extended (to support multiple
experiments within an organization), but this would either require experiments within an organization), but this would either require
coordination within an organization or an IANA registry; the former coordination within an organization or an IANA registry; the former
is prohibitive, and the latter is more complicated than to have IANA is prohibitive, and the latter is more complicated than having IANA
manage the entire space. manage the entire space.
PENs were originally used in SNMP [RFC1157]. PENs are identifiers PENs were originally used in the Simple Network Management Protocol
that can be obtained without cost from IANA [PEN]. Despite the (SNMP) [RFC1157]. PENs are identifiers that can be obtained without
current registry, the size of the PEN assignment space is currently cost from IANA [PEN]. Despite the current registry, the size of the
undefined, and has only recently been proposed (as 32-bits) [Li12]. PEN assignment space is currently undefined and has only recently
PENs are currently assigned to organizations, and there is no been proposed (as 32 bits) [IANA-PEN]. PENs are currently assigned
current process for assigning them to individuals. Finally, if 32- to organizations, and there is no current process for assigning them
bits as expected, they would be larger than needed in many cases. to individuals. Finally, if the PENs are 32 bits as expected, they
would be larger than needed in many cases.
7. Security Considerations 7. Security Considerations
The mechanism described in this document is not intended to provide The mechanism described in this document is not intended to enhance,
(nor does it weaken existing) security for TCP option processing. nor does it weaken the existing state of security for TCP option
processing.
8. IANA Considerations 8. IANA Considerations
This document calls for IANA to create a new TCP experimental option IANA has created a "TCP Experimental Option Experiment Identifiers
Experiment Identifier (ExID) registry. The registry records both 16- (TCP ExIDs)" registry. The registry records both 16-bit and 32-bit
bit and 32-bit ExIDs, as well as a name and e-mail contact for each ExIDs, as well as a reference (description, document pointer, or
entry. ExIDs are registered for use with both TCP experimental assignee name and e-mail contact) for each entry. ExIDs are
option codepoints, i.e., with TCP options with values of 253 and registered for use with both of the TCP experimental option
254. codepoints, i.e., with TCP options with values of 253 and 254.
Entries are assigned on a First-Come, First-Served (FCFS) basis Entries are assigned on a First Come, First Served (FCFS) basis
[RFC5226]. The registry operates FCFS on the first two bytes of the [RFC5226]. The registry operates FCFS on the first two bytes of the
ExID (in network-standard order) but records the entire ExID (in ExID (in network-standard order) but records the entire ExID (in
network-standard order). Some examples are: network-standard order). Some examples are:
o 0x12340000 collides with a previous registration of 0x1234abcd o 0x12340000 collides with a previous registration of 0x1234abcd
o 0x5678 collides with a previous registration of 0x56780123 o 0x5678 collides with a previous registration of 0x56780123
o 0xabcd1234 collides it a previous registration of 0xabcd o 0xabcd1234 collides with a previous registration of 0xabcd
IANA will advise applicants of duplicate entries to select an IANA will advise applicants of duplicate entries to select an
alternate value, as per typical FCFS processing. alternate value, as per typical FCFS processing.
IANA will record known duplicate uses to assist the community in IANA will record known duplicate uses to assist the community in both
both debugging assigned uses as well as correcting unauthorized debugging assigned uses as well as correcting unauthorized duplicate
duplicate uses. uses.
IANA should impose no requirements on making a registration other IANA should impose no requirements on making a registration other
than indicating the desired codepoint and providing a point of than indicating the desired codepoint and providing a point of
contact. A short description or acronym for the use is desired, but contact. A short description or acronym for the use is desired but
should not be required. should not be required.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC [RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, Sep. 1981. 793, September 1981.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4727] Fenner, B., "Experimental Values in IPv4, IPv6, ICMPv4, [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
ICMPv6, UDP, and TCP Headers", RFC 4727, Nov. 2006. ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006.
[RFC5226] Narten, T., H. Alvestrand, "Guidelines for Writing an IANA [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
Considerations Section in RFCs", BCP 26, RFC 5226, May IANA Considerations Section in RFCs", BCP 26, RFC 5226,
2008. May 2008.
9.2. Informative References 9.2. Informative References
[802] "IEEE Standard for Local and Metropolitan Area Networks: [Bi11] Bittau, A., Boneh, D., Hamburg, M., Handley, M., Mazieres,
Overview and Architecture", IEEE 802-2001, 8 March 2002. D., and Q. Slack, "Cryptographic protection of TCP
Streams", Work in Progress, September 2012.
[Bi11] Bittau, A., D. Boneh, M. Hamburg, M. Handley, D. Mazieres, [Ed11]
Q. Slack, "Cryptographic protection of TCP Streams Eddy, W., "Additional TCP Experimental-Use Options", Work
(tcpcrypt)", work in progress, draft-bittau-tcp-crypt-03, in Progress, August 2011.
Sep. 3, 2012.
[Ed11] Eddy, W., "Additional TCP Experimental-Use Options", work [IANA] IANA, <http://www.iana.org/>.
in progress, draft-eddy-tcpm-addl-exp-options-00, Aug. 16,
2011.
[IANA] IANA web pages, http://www.iana.org/ [IANA-PEN] Liang, P. and A. Melnikov, "Private Enterprise Number
(PEN) Practices and Internet Assigned Numbers: Authority
(IANA) Considerations for Registration Procedures", Work
in Progress, June 2012.
[Li12] Liang, P., A. Melnikov, "Private Enterprise Number (PEN) [IEEE802] IEEE, "IEEE Standard for Local and Metropolitan Area
practices and Internet Assigned Numbers: Authority (IANA) Networks: Overview and Architecture", IEEE 802-2001, 8
considerations for registration procedures", draft-liang- March 2002.
iana-pen-01, (work in progress), June 2012.
[OUI] IEEE OUI registry, [OUI] IEEE, "Organizationally Unique Identifier (OUI) or
http://standards.ieee.org/develop/regauth/oui/ 'Company_ID'",
<http://standards.ieee.org/develop/regauth/oui/>.
[PEN] IANA Private Enterprise Numbers, [PEN] IANA, "Private Enterprise Numbers",
http://www.iana.org/assignments/enterprise-numbers <http://www.iana.org/assignments/enterprise-numbers>.
[RFC951] Croft, B., J. Gilmore, "BOOTSTRAP PROTOCOL (BOOTP)", RFC [RFC951] Croft, W. and J. Gilmore, "Bootstrap Protocol", RFC 951,
951, Sept. 1985. September 1985.
[RFC1155] Rose, M., K. McCloghrie, "Structure and Identification of [RFC1155] Rose, M. and K. McCloghrie, "Structure and Identification
Management Information for TCP/IP-based internets", RFC of Management Information for TCP/IP-Based Internets", STD
1155, May 1990. 16, RFC 1155, May 1990.
[RFC1157] Case, J., M. Fedor, M. Schoffstall, J. Davin, "A Simple [RFC1157] Case, J., Fedor, M., Schoffstall, M., and J. Davin,
Network Management Protocol (SNMP)", RFC 1157, May 1990. "Simple Network Management Protocol (SNMP)", RFC 1157, May
1990.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, Oct. 1996. 3", BCP 9, RFC 2026, October 1996.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, Mar. 1997. 2131, March 1997.
[RFC2780] Bradner, S., V. Paxson, "IANA Allocation Guidelines For [RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
Values In the Internet Protocol and Related Headers", BCP Values In the Internet Protocol and Related Headers", BCP
37, RFC 2780, Mar. 2000. 37, RFC 2780, March 2000.
[RFC3692] Narten, T., "Assigning Experimental and Testing Numbers [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers
Considered Useful", BCP 82, RFC 3692, Jan. 2004. Considered Useful", BCP 82, RFC 3692, January 2004.
[RFC6013] Simpson, W., "TCP Cookie Transactions (TCPCT)", RFC 6013, [RFC6013] Simpson, W., "TCP Cookie Transactions (TCPCT)", RFC 6013,
Jan. 2011. January 2011.
[Si11] Simpson, W., "TCP Cookie Transactions (TCPCT) Sockets [Si11] Simpson, W., "TCP Cookie Transactions (TCPCT) Sockets
Application Program Interface (API)", work in progress, Application Program Interface (API)", Work in Progress,
draft-simpson-tcpct-api-04, Apr. 7, 2011. April 2011.
10. Acknowledgments 10. Acknowledgments
This document was motivated by discussions on the IETF TCPM mailing This document was motivated by discussions on the IETF TCPM mailing
list and by Wes Eddy's proposal [Ed11]. Yoshifumi Nishida, Pasi list and by Wes Eddy's proposal [Ed11]. Yoshifumi Nishida, Pasi
Sarolathi, and Michael Scharf provided detailed feedback. Sarolathi, and Michael Scharf provided detailed feedback.
This document was prepared using 2-Word-v2.0.template.dot. This document was originally prepared using 2-Word-v2.0.template.dot.
Authors' Addresses Author's Address
Joe Touch Joe Touch
USC/ISI USC/ISI
4676 Admiralty Way 4676 Admiralty Way
Marina del Rey, CA 90292-6695 U.S.A. Marina del Rey, CA 90292-6695 U.S.A.
Phone: +1 (310) 448-9151 Phone: +1 (310) 448-9151
Email: touch@isi.edu EMail: touch@isi.edu
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