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IETF RFC 5307
IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)
Last modified on Friday, October 3rd, 2008
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Network Working Group K. Kompella, Ed.
Request for Comments: 5307 Y. Rekhter, Ed.
Obsoletes: 4205 Juniper Networks
Updates: 5305 October 2008
Category: Standards Track
IS-IS Extensions in Support of
Generalized Multi-Protocol Label Switching (GMPLS)
 Status of This Memo
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
This document specifies encoding of extensions to the IS-IS routing
protocol in support of Generalized Multi-Protocol Label Switching
(GMPLS).
Kompella & Rekhter Standards Track PAGE 1 
RFC 5307 IS-IS Extensions for GMPLS October 2008
1. Introduction
This document specifies extensions to the IS-IS routing protocol in
support of carrying link state information for Generalized Multi-
Protocol Label Switching (GMPLS). The set of required enhancements
to IS-IS are outlined in [GMPLS-ROUTING]. Support for unnumbered
interfaces assumes support for the "Point-to-Point Three-Way
Adjacency" IS-IS Option type [ISIS-3way].
In this section, we define the enhancements to the Traffic
Engineering (TE) properties of GMPLS TE links that can be announced
in IS-IS Link State Protocol Data Units.
In this document, we enhance the sub-TLVs for the extended IS
reachability TLV (see [ISIS-TE]) in support of GMPLS. Specifically,
we add the following sub-TLVs:
Sub-TLV Type Length Name
4 8 Link Local/Remote Identifiers
20 2 Link Protection Type
21 variable Interface Switching Capability
Descriptor
We further add one new TLV to the TE TLVs:
TLV Type Length Name
138 variable GMPLS-SRLG
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 [RFC 2119].
1.1. Link Local/Remote Identifiers
A Link Local Interface Identifier is a sub-TLV of the extended IS
reachability TLV. The type of this sub-TLV is 4, and the length is 8
octets. The value field of this sub-TLV contains 4 octets of Link
Local Identifier followed by 4 octets of Link Remote Identifier (see
Section 2.1, "Support for Unnumbered Links", of [GMPLS-ROUTING]). If
the Link Remote Identifier is unknown, it is set to 0.
The following illustrates encoding of the Value field of the Link
Local/Remote Identifiers sub-TLV.
Kompella & Rekhter Standards Track PAGE 2
RFC 5307 IS-IS Extensions for GMPLS October 2008
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Remote Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Link Local/Remote Identifiers sub-TLV MUST NOT occur more than
once within the extended IS reachability TLV. If the Link
Local/Remote Identifiers sub-TLV occurs more than once within the
extended IS reachability TLV, the receiver SHOULD ignore all these
sub-TLVs.
1.2. Link Protection Type
The Link Protection Type is a sub-TLV (of type 20) of the extended IS
reachability TLV, with a length of 2 octets.
The following illustrates encoding of the Value field of the Link
Protection Type sub-TLV.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Protection Cap | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The first octet is a bit vector describing the protection capabilities
of the link (see Section 2.2, "Link Protection Type", of
[GMPLS-ROUTING]). They are:
0x01 Extra Traffic
0x02 Unprotected
0x04 Shared
0x08 Dedicated 1:1
0x10 Dedicated 1+1
0x20 Enhanced
0x40 Reserved
0x80 Reserved
Kompella & Rekhter Standards Track PAGE 3
RFC 5307 IS-IS Extensions for GMPLS October 2008
The second octet SHOULD be set to zero by the sender, and SHOULD be
ignored by the receiver.
The Link Protection Type sub-TLV MUST NOT occur more than once within
the extended IS reachability TLV. If the Link Protection Type sub-
TLV occurs more than once within the extended IS reachability TLV,
the receiver SHOULD ignore all these sub-TLVs.
1.3. Interface Switching Capability Descriptor
The Interface Switching Capability Descriptor is a sub-TLV (of type
21) of the extended IS reachability TLV. The length is the length of
the value field in octets. The following illustrates encoding of the
Value field of the Interface Switching Capability Descriptor sub-TLV.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Switching Cap | Encoding | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Switching Capability-specific information |
| (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Kompella & Rekhter Standards Track PAGE 4
RFC 5307 IS-IS Extensions for GMPLS October 2008
The Switching Capability (Switching Cap) field contains one of the
following values:
1 Packet-Switch Capable-1 (PSC-1)
2 Packet-Switch Capable-2 (PSC-2)
3 Packet-Switch Capable-3 (PSC-3)
4 Packet-Switch Capable-4 (PSC-4)
51 Layer-2 Switch Capable (L2SC)
100 Time-Division-Multiplex Capable (TDM)
150 Lambda-Switch Capable (LSC)
200 Fiber-Switch Capable (FSC)
The Encoding field contains one of the values specified in Section
3.1.1 of [GMPLS-SIG].
Maximum Link State Protocol Data Unit (LSP) Bandwidth is encoded as a
list of eight 4-octet fields in the IEEE floating point format
[IEEE], with priority 0 first and priority 7 last. The units are
bytes (not bits!) per second.
The content of the Switching Capability specific information field
depends on the value of the Switching Capability field.
When the Switching Capability field is PSC-1, PSC-2, PSC-3, or PSC-4,
the Switching Capability specific information field includes Minimum
LSP Bandwidth and Interface MTU.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum LSP Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface MTU |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Minimum LSP Bandwidth is encoded in a 4-octet field in the IEEE
floating point format. The units are bytes (not bits!) per second.
The Interface MTU is encoded as a 2-octet integer, and carries the
MTU value in the units of bytes.
When the Switching Capability field is L2SC, there is no Switching
Capability specific information field present.
When the Switching Capability field is TDM, the Switching Capability
specific information field includes Minimum LSP Bandwidth and an
indication whether the interface supports Standard or Arbitrary
SONET/SDH (Synchronous Optical Network / Synchronous Digital
Hierarchy).
Kompella & Rekhter Standards Track PAGE 5
RFC 5307 IS-IS Extensions for GMPLS October 2008
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum LSP Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Indication |
+-+-+-+-+-+-+-+-+
The Minimum LSP Bandwidth is encoded in a 4-octet field in the IEEE
floating point format. The units are bytes (not bits!) per second.
The indication whether the interface supports Standard or Arbitrary
SONET/SDH is encoded as 1 octet. The value of this octet is 0 if the
interface supports Standard SONET/SDH, and 1 if the interface
supports Arbitrary SONET/SDH.
When the Switching Capability field is LSC, there is no Switching
Capability specific information field present.
To support interfaces that have more than one Interface Switching
Capability Descriptor (see Section 2.4, "Interface Switching
Capability Descriptor", of [GMPLS-ROUTING]) the Interface Switching
Capability Descriptor sub-TLV MAY occur more than once within the
extended IS reachability TLV.
1.4. Shared Risk Link Group TLV
The Shared Risk Link Group (SRLG) TLV (of type 138) contains a data
structure consisting of:
6 octets of System ID
1 octet of Pseudonode Number
1 octet Flag
4 octets of IPv4 interface address or 4 octets of a Link Local
Identifier
4 octets of IPv4 neighbor address or 4 octets of a Link Remote
Identifier
(variable) list of SRLG values, where each element in the list
has 4 octets.
The following illustrates encoding of the Value field of the SRLG
TLV.
Kompella & Rekhter Standards Track PAGE 6
RFC 5307 IS-IS Extensions for GMPLS October 2008
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| System ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| System ID (cont.) | Pseudonode num| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 interface address/Link Local Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 neighbor address/Link Remote Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ............ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The neighbor is identified by its System ID (6 octets), plus one
octet to indicate the pseudonode number if the neighbor is on a LAN
interface.
The least significant bit of the Flag octet indicates whether the
interface is numbered (set to 1) or unnumbered (set to 0). All other
bits are reserved and should be set to 0.
The length of this TLV is 16 + 4 * (number of SRLG values).
This TLV carries the Shared Risk Link Group information (see Section
2.3, "Shared Risk Link Group Information", of [GMPLS-ROUTING]).
The SRLG TLV MAY occur more than once within the IS-IS Link State
Protocol Data Units.
1.5. Link Identifier for Unnumbered Interfaces
Link Identifiers are exchanged in the Extended Local Circuit ID field
of the "Point-to-Point Three-Way Adjacency" IS-IS Option type [ISIS-
3way].
2. Implications on Graceful Restart
The restarting node SHOULD follow the IS-IS restart procedures
[ISIS-RESTART] and the RSVP-TE restart procedures [GMPLS-RSVP].
When the restarting node is going to originate its IS-IS Link State
Protocol Data Units for TE links, these Link State Protocol Data
Units SHOULD be originated with 0 unreserved bandwidth, Traffic
Kompella & Rekhter Standards Track PAGE 7
RFC 5307 IS-IS Extensions for GMPLS October 2008
Engineering Default metric set to 0xffffff. Also, if the link has
LSC or FSC as its Switching Capability, then they SHOULD be
originated with 0 as Max LSP Bandwidth, until the node is able to
determine the amount of unreserved resources taking into account the
resources reserved by the already established LSPs that have been
preserved across the restart. Once the restarting node determines
the amount of unreserved resources, taking into account the resources
reserved by the already established LSPs that have been preserved
across the restart, the node SHOULD advertise these resources in its
Link State Protocol data units.
In addition, in the case of a planned restart prior to restarting,
the restarting node SHOULD originate the IS-IS Link State Protocol
data units for TE links with 0 as unreserved bandwidth. Also, if the
link has LSC or FSC as its Switching Capability, then they SHOULD be
originated with 0 as Max LSP Bandwidth. This would discourage new
LSP establishment through the restarting router.
Neighbors of the restarting node SHOULD continue to advertise the
actual unreserved bandwidth on the TE links from the neighbors to
that node.
3. Security Considerations
This document specifies the contents of GMPLS TE TLVs in IS-IS. As
these TLVs are not used for SPF computation or normal routing, the
extensions specified here have no direct effect on IP routing.
Tampering with GMPLS TE TLVs may have an effect on the underlying
transport (optical and/or SONET/SDH) network. Mechanisms to secure
IS-IS Link State PDUs and/or the TE TLVs [ISIS-HMAC] can be used to
secure the GMPLS TE TLVs as well.
For a discussion of general security considerations for IS-IS, see
[ISIS-HMAC].
4. IANA Considerations
This document defines the following new IS-IS TLV type that has been
reflected in the IS-IS TLV codepoint registry:
Type Description IIH LSP SNP
---- ---------------------- --- --- ---
138 Shared Risk Link Group n y n
This document also defines the following new sub-TLV types of top-
level TLV 22 that have been reflected in the IS-IS sub-TLV registry
for TLV 22:
Kompella & Rekhter Standards Track PAGE 8
RFC 5307 IS-IS Extensions for GMPLS October 2008
Type Description Length
---- ------------------------------ --------
4 Link Local/Remote Identifiers 8
20 Link Protection Type 2
21 Interface Switching Capability variable
Descriptor
5. References
5.1. Normative References
[GMPLS-ROUTING] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
Extensions in Support of Generalized Multi-Protocol
Label Switching (GMPLS)", RFC 4202, October 2005.
[GMPLS-RSVP] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[GMPLS-SIG] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description",
RFC 3471, January 2003
[IEEE] IEEE, "IEEE Standard for Binary Floating-Point
Arithmetic", Standard 754-1985, 1985 (ISBN
1-5593-7653-8).
[ISIS-3way] Katz, D. and R. Saluja, "Three-Way Handshake for IS-
IS Point-to-Point Adjacencies", RFC 5303, October
2008.
[ISIS-HMAC] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, October 2008.
[ISIS-RESTART] Shand, M. and L. Ginsberg, "Restart Signaling for
IS-IS", RFC 5306, October 2008.
[ISIS-TE] Smit, H. and T. Li, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
6. Acknowledgements
The authors would like to thank Jim Gibson, Suresh Katukam, Jonathan
Lang, and Quaizar Vohra for their comments on the document.
Kompella & Rekhter Standards Track PAGE 9
RFC 5307 IS-IS Extensions for GMPLS October 2008
7. Contributors
Ayan Banerjee
Calient Networks
5853 Rue Ferrari
San Jose, CA 95138
Phone: +1 408 972 3645
EMail: abanerjee@calient.net
John Drake
Calient Networks
5853 Rue Ferrari
San Jose, CA 95138
Phone: +1 408 972 3720
EMail: jdrake@calient.net
Greg Bernstein
Grotto Networking
EMail: gregb@grotto-networking.com
Don Fedyk
Nortel Networks Corp.
600 Technology Park Drive
Billerica, MA 01821
Phone: +1 978 288 4506
EMail: dwfedyk@nortelnetworks.com
Eric Mannie
Independent Consultant
EMail: eric_mannie@hotmail.com
Kompella & Rekhter Standards Track PAGE 10
RFC 5307 IS-IS Extensions for GMPLS October 2008
Debanjan Saha
Tellium Optical Systems
2 Crescent Place
P.O. Box 901
Ocean Port, NJ 07757
Phone: +1 732 923 4264
EMail: dsaha@tellium.com
Vishal Sharma
EMail: v.sharma@ieee.org
Authors' Addresses
Kireeti Kompella (editor)
Juniper Networks, Inc.
1194 N. Mathilda Ave
Sunnyvale, CA 94089
EMail: kireeti@juniper.net
Yakov Rekhter (editor)
Juniper Networks, Inc.
1194 N. Mathilda Ave
Sunnyvale, CA 94089
EMail: yakov@juniper.net
Kompella & Rekhter Standards Track PAGE 11
RFC 5307 IS-IS Extensions for GMPLS October 2008
Full Copyright Statement
Copyright © The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
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OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
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Kompella & Rekhter Standards Track PAGE 12
IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)
RFC TOTAL SIZE: 22619 bytes
PUBLICATION DATE: Friday, October 3rd, 2008
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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