draft-ietf-isis-link-attr-03.txt   rfc5029.txt 
Networking Working Group JP. Vasseur Network Working Group JP. Vasseur
Internet-Draft S. Previdi Request for Comments: 5029 S. Previdi
Intended status: Standards Track Cisco Systems, Inc Category: Standards Track Cisco Systems, Inc
Expires: August 10, 2007 February 6, 2007 September 2007
Definition of an IS-IS Link Attribute sub-TLV
draft-ietf-isis-link-attr-03.txt
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This Internet-Draft will expire on August 10, 2007. Definition of an IS-IS Link Attribute Sub-TLV
Copyright Notice Status of This Memo
Copyright (C) The IETF Trust (2007). This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract Abstract
This document defines a sub-TLV called "Link-attributes" carried This document defines a sub-TLV called "Link-attributes" carried
within the TLV 22 and used to flood some link characteristics. within the TLV 22 and used to flood some link characteristics.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................2
2. Link-attributes sub-TLV format . . . . . . . . . . . . . . . . 3 1.1. Terminology ................................................2
3. Interoperability with routers non supporting this 2. Link-Attributes Sub-TLV Format ..................................2
capability . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Interoperability with Routers Not Supporting This Capability ....3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations .............................................3
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations .........................................3
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements ................................................3
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7. References ......................................................4
7.1. Normative References . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References .......................................4
7.2. Informative References . . . . . . . . . . . . . . . . . . 5 7.2. Informative References .....................................4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
Intellectual Property and Copyright Statements . . . . . . . . . . 6
1. Introduction 1. Introduction
[IS-IS] specifies the IS-IS protocol (ISO 10589) with extensions to [IS-IS] specifies the IS-IS protocol (ISO 10589) with extensions to
support IPv4 in [RFC1195]. A router advertises one or several Link support IPv4 in [RFC1195]. A router advertises one or several Link
State Protocol data units which are composed of variable length State Protocol data units that are composed of variable length tuples
tuples called TLVs (Type-Length-Value). called TLVs (Type-Length-Value).
[RFC3784] defines a set of new TLVs whose aims are to add more [RFC3784] defines a set of new TLVs whose aims are to add more
information about links characteristics, increase the range of IS-IS information about links characteristics, increase the range of IS-IS
metrics and optimize the encoding of IS-IS prefixes. metrics, and optimize the encoding of IS-IS prefixes.
This document defines a new sub-TLV named "Link-attributes" carried This document defines a new sub-TLV named "Link-attributes" carried
within the extended IS reachability TLV (type 22) specified in within the extended IS reachability TLV (type 22) specified in
[RFC3784]. [RFC3784].
2. Link-attributes sub-TLV format 1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Link-Attributes Sub-TLV Format
The link-attribute sub-TLV is carried within the TLV 22 and has a The link-attribute sub-TLV is carried within the TLV 22 and has a
format identical to the sub-TLV format used by the Traffic format identical to the sub-TLV format used by the Traffic
Engineering Extensions for IS-IS ([RFC3784]): 1 octet of sub-type, 1 Engineering Extensions for IS-IS ([RFC3784]): 1 octet of sub-type, 1
octet of length of the value field of the sub-TLV followed by the octet of length of the value field of the sub-TLV followed by the
value field - in this case, a 16 bit flags field. value field -- in this case, a 16 bit flags field.
The Link-attribute sub-type is 19 (to be assigned by IANA) and has a The Link-attribute sub-type is 19 and the link-attribute has a length
length of 2 octets. of 2 octets.
This sub-TLV is OPTIONAL and MUST appear at most once for a single IS This sub-TLV is OPTIONAL and MUST appear at most once for a single IS
neighbor. If a received LSP contains more than one Link-Attribute neighbor. If a received Link State Packet (LSP) contains more than
Sub-TLV, an implementation MAY decide to consider only the first one Link-Attribute Sub-TLV, an implementation SHOULD decide to
encountered instance. consider only the first encountered instance.
The following bits are defined: The following bits are defined:
Local Protection Available (0x01). When set, this indicates that the Local Protection Available (0x01). When set, this indicates that the
link is protected by means of some local protection mechanism (e.g link is protected by means of some local protection mechanism (e.g.,
[RFC4090]). [RFC4090]).
Link excluded from local protection path (0x02). When set, this link Link excluded from local protection path (0x02). When set, this link
SHOULD not be included in any computation of a repair path by any SHOULD not be included in any computation of a repair path by any
other router in the routing area. The triggers for setting up this other router in the routing area. The triggers for setting up this
bit are out of the scope of this document. bit are out of the scope of this document.
3. Interoperability with routers non supporting this capability 3. Interoperability with Routers Not Supporting This Capability
A router not supporting the link-attribute sub-TLV will just silently A router not supporting the link-attribute sub-TLV will just silently
ignore this sub-TLV. ignore this sub-TLV.
4. IANA Considerations 4. IANA Considerations
IANA will assign a new codepoint for the link-attribute sub-TLV IANA has assigned codepoint 19 for the link-attribute sub-TLV defined
defined in this document and carried within TLV 22. Suggested value in this document and carried within TLV 22.
is 19 (to be assigned by IANA).
IANA is requested to create a registry for bit values inside the IANA has created a registry for bit values inside the link-attributes
link-attributes sub-TLV. The initial contents of this registry will sub-TLV. The initial contents of this registry are as follows
be:
Value Name Reference Value Name Reference
----- ---- --------- ----- ---- ---------
0x1 Local Protection Available [This Document] 0x1 Local Protection Available [RFC5029]
0x2 Link Excluded from Local Protection [This Document] 0x2 Link Excluded from Local Protection [RFC5029]
Further values are to be allocated by the Standards Action process Further values are to be allocated by the Standards Action process
defined in [RFC2434], with Early Allocation (defined in [RFC4020]) defined in [RFC2434], with Early Allocation (defined in [RFC4020])
permitted. permitted.
5. Security Considerations 5. Security Considerations
Any new security issues raised by the procedures in this document Any new security issues raised by the procedures in this document
depend upon the opportunity for LSPs to be snooped and modified, the depend upon the opportunity for LSPs to be snooped and modified, the
ease/difficulty of which has not been altered. As the LSPs may now ease/difficulty of which has not been altered. As the LSPs may now
contain additional information regarding router capabilities, this contain additional information regarding router capabilities, this
new information would also become available to an attacker. new information would also become available to an attacker.
Specifications based on this mechanism need to describe the security Specifications based on this mechanism need to describe the security
considerations around the disclosure and modification of their considerations around the disclosure and modification of their
information. Note that an integrity mechanism, such as one defined information. Note that an integrity mechanism, such as one defined
in [RFC3567] should be applied if there is high risk resulting from in [RFC3567], should be applied if there is high risk resulting from
modification of capability information. the modification of capability information.
6. Acknowledgements 6. Acknowledgements
The authors would like to thank Mike Shand, Les Ginsberg and Bill The authors would like to thank Mike Shand, Les Ginsberg, and Bill
Fenner for their useful comments. Fenner for their useful comments.
7. References 7. References
7.1. Normative References 7.1. Normative References
[IS-IS] "Intermediate System to Intermediate System Intra-Domain [IS-IS] "Intermediate System to Intermediate System Intra-Domain
Routeing Exchange Protocol for use in Conjunction with the Protocol Routing Exchange Protocol for use in Conjunction with the
for Providing the Connectionless-mode Network Service (ISO 8473)", Protocol for Providing the Connectionless-mode Network
ISO 10589. Service (ISO 8473)", ISO 10589.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990. dual environments", RFC 1195, December 1990.
[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.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434, IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998. October 1998.
[RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate [RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE)", System (IS-IS) Extensions for Traffic Engineering (TE)",
RFC 3784, June 2004. RFC 3784, June 2004.
[RFC4020] Kompella, K. and A. Zinin, "Early IANA Allocation of [RFC4020] Kompella, K. and A. Zinin, "Early IANA Allocation of
Standards Track Code Points", BCP 100, RFC 4020, Standards Track Code Points", BCP 100, RFC 4020, February
February 2005. 2005.
7.2. Informative References 7.2. Informative References
[RFC3567] Li, T. and R. Atkinson, "Intermediate System to [RFC3567] Li, T. and R. Atkinson, "Intermediate System to
Intermediate System (IS-IS) Cryptographic Authentication", Intermediate System (IS-IS) Cryptographic Authentication",
RFC 3567, July 2003. RFC 3567, July 2003.
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", RFC 4090, Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May
May 2005. 2005.
Authors' Addresses Authors' Addresses
JP Vasseur JP Vasseur
Cisco Systems, Inc Cisco Systems, Inc
1414 Massachusetts Avenue 1414 Massachusetts Avenue
Boxborough, MA 01719 Boxborough, MA 01719
USA USA
Email: jpv@cisco.com EMail: jpv@cisco.com
Stefano Previdi Stefano Previdi
Cisco Systems, Inc Cisco Systems, Inc
Via Del Serafico 200 Via Del Serafico 200
Roma, 00142 Roma 00142
Italy Italy
Email: sprevidi@cisco.com EMail: sprevidi@cisco.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
skipping to change at page 6, line 44 skipping to change at line 217
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Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
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