Network Working Group
Request for Comments: 4205
Updates: 3784
Category: Informational

K. Kompella, Ed.
Y. Rekhter, Ed.
Juniper Networks
October 2005

Intermediate System to Intermediate System (IS-IS) Extensions

in Support of Generalized Multi-Protocol Label Switching (GMPLS)

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

Abstract

This document specifies encoding of extensions to the IS-IS routing protocol in support of Generalized Multi-Protocol Label Switching (GMPLS).

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  Shared Risk Link Group

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].

1.1. Link Local/Remote Identifiers

A Link Local Interface Identifiers is a sub-TLV of the extended IS reachability TLV. The type of this sub-TLV is 4, and length is eight octets. The value field of this sub-TLV contains four octets of Link Local Identifier followed by four octets of Link Remote Identifier (see Section "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.

       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 length two 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 "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

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 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)                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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 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 octets field in the IEEE floating point format. The units are bytes (not bits!) per second. The Interface MTU is encoded as a 2 octets 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.

       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 octets 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 "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 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.

       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 neighbors 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 "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 ISIS 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 Engineering Default metric set to 0xffffff, and if the link has LSC or FSC as its Switching Capability then also 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, and if the link has LSC or FSC as its Switching Capability then also 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. 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

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

4. Acknowledgements

The authors would like to thank Jim Gibson, Suresh Katukam, Jonathan Lang and Quaizar Vohra for their comments on the draft.

5. Security Considerations

This document specifies the contents of GMPLS TE TLVs in ISIS. 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 ISIS Link State PDUs and/or the TE TLVs [ISIS-HMAC] can be used to secure the GMPLS TE TLVs as well.

6. IANA Considerations

This document defines the following new ISIS TLV type that needs to be reflected in the ISIS TLV code-point 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 need to be reflected in the ISIS sub-TLV registry for TLV 22:

          Type        Description                        Length
          ----        ------------------------------   --------
             4        Link Local/Remote Identifiers           8
            20        Link Protection Type                    2
            21        Interface Switching Capability   variable
                      Descriptor

References

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., "Generalized Multi-Protocol Label
                   Switching (GMPLS) Signaling Resource ReserVation
                   Protocol-Traffic Engineering (RSVP-TE) Extensions",
                   RFC 3473, January 2003.
   
   [GMPLS-SIG]     Berger, L., "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
                   Intermediate System to Intermediate System (IS-IS)
                   Point-to-Point Adjacencies", RFC 3373, September
                   2002.
   
   [ISIS-RESTART]  Shand, M. and L. Ginsberg, "Restart Signaling for
                   Intermediate System to Intermediate System (IS-IS)",
                   RFC 3847, July 2004.
   
   [ISIS-TE]       Smit, H. and T. Li, "Intermediate System to
                   Intermediate System (IS-IS) Extensions for Traffic
                   Engineering (TE)", RFC 3784, June 2004.
   
   [RFC2119]       Bradner, S., "Key words for use in RFCs to Indicate
                   Requirement Levels", BCP 14, RFC 2119, March 1997.
   
   [ISIS-HMAC]     Li, T. and R. Atkinson, "Intermediate System to
                   Intermediate System (IS-IS) Cryptographic
                   Authentication", RFC 3567, July 2003.

Authors' Addresses

Kireeti Kompella
Juniper Networks, Inc.
1194 N. Mathilda Ave
Sunnyvale, CA 94089

EMail:

          kireeti@juniper.net

Yakov Rekhter
Juniper Networks, Inc.
1194 N. Mathilda Ave
Sunnyvale, CA 94089

EMail:

          yakov@juniper.net

Full Copyright Statement

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 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Intellectual Property

The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79.

Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr.

The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org.

Acknowledgement

Funding for the RFC Editor function is currently provided by the Internet Society.