IS-IS reserved TLVs: Reserved Type, Length and Value (TLV) Codepoints in Intermediate System to Intermediate System
A shared list of which type numbers IS-IS routers already use, kept so new extensions do not collide.
Przygienda, T., "Reserved Type, Length and Value (TLV) Codepoints in Intermediate System to Intermediate System", RFC 3359, DOI 10.17487/RFC3359, August 2002, <https://www.rfc-editor.org/info/rfc3359>.
@misc{rfc3359,
series = {Request for Comments},
number = 3359,
howpublished = {RFC 3359},
publisher = {RFC Editor},
doi = {10.17487/RFC3359},
url = {https://www.rfc-editor.org/info/rfc3359},
author = {T. Przygienda},
title = {{Reserved Type, Length and Value (TLV) Codepoints in Intermediate System to Intermediate System}},
pagetotal = 5,
year = 2002,
month = aug,
} RFC text
Contents
Network Working Group T. Przygienda
Request for Comments: 3359 Xebeo
Category: Informational August 2002
Reserved Type, Length and Value (TLV) Codepoints in
Intermediate System to Intermediate System
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document describes implementation codepoints within Intermediate
System to Intermediate System (IS-IS) used today by several ISPs for
routing within their clouds. IS-IS is an interior gateway routing
protocol developed originally by OSI and used with IP extensions as
Interior Gateway Protocol (IGP). This document summarizes all Table,
Length and Value (TLV) codepoints that are being used by the protocol
and its pending extensions.
1. TLV Codepoints Reserved
_____________________________________________________________________
Name Value IIH LSP SNP Status
_____________________________________________________________________
Area Addresses 1 y y n ISO 10589
IIS Neighbors 2 n y n ISO 10589
ES Neighbors 3 n y n ISO 10589
Part. DIS 4 n y n ISO 10589
Prefix Neighbors 5 n y n ISO 10589
IIS Neighbors 6 y n n ISO 10589
Padding 8 y n n ISO 10589
LSP Entries 9 n n y ISO 10589
Authentication 10 y y y ISO 10589
Opt. Checksum 12 y n y IETF-draft
LSPBufferSize 14 n y n ISO 10589 Rev 2 Draft
TE IIS Neigh. 22 n y n IETF-draft
DECnet Phase IV 42 y n n DEC (ancient)
Lucent Proprietary 66 n y n
IP Int. Reach 128 n y n RFC 1195
Prot. Supported 129 y y n RFC 1195
IP Ext. Address 130 n y n RFC 1195
IDRPI 131 n y y RFC 1195
IP Intf. Address 132 y y n RFC 1195
Illegal 133 n n n RFC 1195 (not used)
Router ID 134 n y n IETF-draft
TE IP. Reach 135 n y n IETF-draft
Dynamic Name 137 n y n RFC 2763
Nortel Proprietary 176 n y n
Nortel Proprietary 177 n y n
Restart TLV 211 y n n IETF-draft
MT-ISN 222 n y n IETF-draft
M-Topologies 229 y y n IETF-draft
IPv6 Intf. Addr. 232 y y n IETF-draft
MT IP. Reach 235 n y n IETF-draft
IPv6 IP. Reach 236 n y n IETF-draft
MT IPv6 IP. Reach 237 n y n IETF-draft
P2P Adjacency State 240 y n n IETF-draft
2. Assignment Procedures
This document is provided to avoid possible future conflicts in the
assignment of TLV numbers. It does not constitute or represent any
standard or authority assigning TLV numbers. TLV assignment happens
on a shared, informational basis between the ISO, SIF and the IETF
working groups. The core ISIS protocol is being specified in the ISO
standards body, IP extensions to it however are products of the ISIS
working group in IETF. Since ISO does not provide a numbering
authority and IANA is only responsible for IP related coding points,
no plausible central authority to assign TLV numbers exists as of
today.
This document will be periodically updated by newer versions in the
fashion of [RP94] and successors. It may be replaced at any given
point in time by some type of official registry.
This document will not indicate specific documents using the
codepoints, nor will it resolve the sub-TLV codepoints.
3. Acknowledgments
Thanks to Les Ginsberg and others for pointing out details and
improving this work.
4. Security Consideration
ISIS security applies to the work presented. No specific security
issues are being introduced.
5. References
[Cal90a] R. Callon. OSI ISIS Intradomain Routing Protocol.
INTERNET-RFC, Internet Engineering Task Force, February
1990.
[Cal90b] R. Callon. Use of OSI ISIS for Routing in TCP/IP and Dual
Environments. INTERNET-RFC, Internet Engineering Task
Force, December 1990.
[ISO90] ISO. Information Technology - Telecommunications and
Information Exchange between Systems - Intermediate System
to Intermediate System Routing Exchange Protocol for Use in
Conjunction with the Protocol for Providing the
Connectionless-Mode Network Service. ISO, 1990.
[RP94] Reynolds, J., "Assigned Numbers; RFC 1700 is Replaced by an
On-line Database", RFC 3232, January, 2002.
6. Authors' Addresses
Tony Przygienda
Xebeo
One Cragwood Road
South Plainfield, NJ 07080
Phone: (908) 222 4225
Email: prz@xebeo.com
7. Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
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followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
AI ELI5
On this page
§1Why a List of Codepoints
IS-IS is an interior gateway routing protocol, developed originally by OSI and used with IP extensions. Its messages hold information in TLV blocks: a type, a length and a value. The RFC says it describes codepoints in use by several ISPs for routing within their clouds, and covers the pending extensions too.
The point is to avoid future conflicts. The core protocol is specified by ISO, while the IP extensions come from the IETF IS-IS working group. ISO provides no numbering authority and IANA covers only IP-related code points, so the memo says no plausible central authority exists.
Many people add new kinds of notes to the same message format. A shared list keeps two people from using the same label for different things.
§2The Reserved TLV Table
The table has one row per TLV: its name, its value, whether it may appear in IIH (hello), LSP (link state) and SNP (sequence number) packets, and its status. Status says where the code comes from, such as ISO 10589, RFC 1195, RFC 2763 or an IETF-draft.
Examples are Area Addresses (1), Padding (8), Authentication (10), IP Int. Reach (128), Protocols Supported (129), Dynamic Name (137), IPv6 Intf. Addr. (232) and P2P Adjacency State (240). Two rows are vendor-specific (Lucent 66, Nortel 176 and 177), and DECnet Phase IV (42) is marked ancient. Code 133 is marked Illegal and not used.
It is a big chart: each tag has a number, a name, and which kinds of messages may carry it.
§3Assignment Procedures and Security
The document does not constitute or represent any standard or authority assigning TLV numbers. Assignment happens on a shared, informational basis between ISO, SIF and the IETF working groups. It is to be updated periodically, in the fashion of the Assigned Numbers practice, and may be replaced at any point by some type of official registry. It does not name documents using the codepoints and does not cover sub-TLV codepoints.
On security, the RFC says IS-IS security applies and no specific security issues are introduced.
The list is a friendly notice board, not a rulebook. A real official list might replace it one day.