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rfc:rfc4205

Network Working Group K. Kompella, Ed. Request for Comments: 4205 Y. Rekhter, Ed. Updates: 3784 Juniper Networks Category: Informational 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

 Copyright (C) The Internet Society (2005).

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

Kompella & Rekhter Informational [Page 1] RFC 4205 IS-IS Extensions for MPLS October 2005

 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   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Kompella & Rekhter Informational [Page 2] RFC 4205 IS-IS Extensions for MPLS October 2005

 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.

Kompella & Rekhter Informational [Page 3] RFC 4205 IS-IS Extensions for MPLS October 2005

     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.

Kompella & Rekhter Informational [Page 4] RFC 4205 IS-IS Extensions for MPLS October 2005

 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.

Kompella & Rekhter Informational [Page 5] RFC 4205 IS-IS Extensions for MPLS October 2005

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]).

Kompella & Rekhter Informational [Page 6] RFC 4205 IS-IS Extensions for MPLS October 2005

 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.

Kompella & Rekhter Informational [Page 7] RFC 4205 IS-IS Extensions for MPLS October 2005

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

Kompella & Rekhter Informational [Page 8] RFC 4205 IS-IS Extensions for MPLS October 2005

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.

Kompella & Rekhter Informational [Page 9] RFC 4205 IS-IS Extensions for MPLS October 2005

 [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

Kompella & Rekhter Informational [Page 10] RFC 4205 IS-IS Extensions for MPLS October 2005

Full Copyright Statement

 Copyright (C) The Internet Society (2005).
 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.

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Acknowledgement

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

Kompella & Rekhter Informational [Page 11]

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