Network Working Group
Request for Comments: 4203
Updates: 3630
Category: Standards Track

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

OSPF 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.

Copyright Notice

Abstract

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

1. Introduction

This document specifies extensions to the OSPF routing protocol [OSPF] in support of carrying link state information for Generalized Multi-Protocol Label Switching (GMPLS). The set of required enhancements to OSPF are outlined in [GMPLS-ROUTING].

In this section, we define the enhancements to the Traffic Engineering (TE) properties of GMPLS TE links that can be announced in OSPF TE LSAs. The TE LSA, which is an opaque LSA with area flooding scope [OSPF-TE], has only one top-level Type/Length/Value (TLV) triplet and has one or more nested sub-TLVs for extensibility. The top-level TLV can take one of two values (1) Router Address or (2) Link. In this document, we enhance the sub-TLVs for the Link TLV in support of GMPLS. Specifically, we add the following sub-TLVs to the Link TLV:

   Sub-TLV Type      Length    Name
             11           8    Link Local/Remote Identifiers
             14           4    Link Protection Type
             15    variable    Interface Switching Capability Descriptor
             16    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 BCP 14, RFC 2119 [RFC2119].

1.1. Link Local/Remote Identifiers

Link Local/Remote Identifiers is a sub-TLV of the Link TLV. The type of this sub-TLV is 11, 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.

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

A node can communicate its Link Local Identifier to its neighbor using a link local Opaque LSA, as described in Section "Exchanging Link Local TE Information".

1.2. Link Protection Type

The Link Protection Type is a sub-TLV of the Link TLV. The type of this sub-TLV is 14, and length is four octets.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |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 remaining three octets SHOULD be set to zero by the sender, and SHOULD be ignored by the receiver.

The Link Protection Type sub-TLV may occur at most once within the Link TLV.

1.3. Shared Risk Link Group (SRLG)

The SRLG is a sub-TLV (of type 16) of the Link TLV. The length is the length of the list in octets. The value is an unordered list of 32 bit numbers that are the SRLGs that the link belongs to. The format of the value field is as shown below:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Shared Risk Link Group Value                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        ............                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Shared Risk Link Group Value                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

This sub-TLV carries the Shared Risk Link Group information (see Section "Shared Risk Link Group Information" of [GMPLS-ROUTING]).

The SRLG sub-TLV may occur at most once within the Link TLV.

1.4. Interface Switching Capability Descriptor

The Interface Switching Capability Descriptor is a sub-TLV (of type 15) of the Link TLV. The length is the length of value field in octets. The format of the value field is as shown below:

    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, Interface MTU, and padding.

    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       |            Padding            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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. The padding is 2 octets, and is used to make the Interface Switching Capability Descriptor sub-TLV 32-bits aligned. It SHOULD be set to zero by the sender and SHOULD be ignored by the receiver.

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, an indication whether the interface supports Standard or Arbitrary SONET/SDH, and padding.

    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  |                 Padding                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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. The padding is 3 octets, and is used to make the Interface Switching Capability Descriptor sub-TLV 32-bits aligned. It SHOULD be set to zero by the sender and SHOULD be ignored by the receiver.

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 Link TLV.

2. Implications on Graceful Restart

The restarting node should follow the OSPF restart procedures [OSPF-RESTART], and the RSVP-TE restart procedures [GMPLS-RSVP].

When a restarting node is going to originate its TE LSAs, the TE LSAs containing Link TLV should be originated with 0 unreserved bandwidth, Traffic Engineering metric set to 0xffffffff, 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 TE LSAs.

In addition in the case of a planned restart prior to restarting, the restarting node SHOULD originate the TE LSAs containing Link TLV 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 advertise the actual unreserved bandwidth on the TE links from the neighbors to that node.

Regular graceful restart should not be aborted if a TE LSA or TE topology changes. TE graceful restart need not be aborted if a TE LSA or TE topology changes.

3. Exchanging Link Local TE Information

It is often useful for a node to communicate some Traffic Engineering information for a given interface to its neighbors on that interface. One example of this is a Link Local Identifier. If nodes X and Y are connected by an unnumbered point-to-point interface I, then X's Link Local Identifier for I is Y's Link Remote Identifier for I. X can communicate its Link Local Identifier for I by exchanging with Y a TE link local opaque LSA described below. Note that this information need only be exchanged over interface I, hence the use of a link local Opaque LSA.

A TE Link Local LSA is an opaque LSA of type 9 (link-local flooding scope) with Opaque Type 1 (TE LSA) and Opaque ID of 0.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            LS age             |    Options    |       9       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Opaque Type  |                   Opaque ID                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Advertising Router                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     LS sequence number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         LS checksum           |             length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +-                            TLVs                             -+
   |                             ...                               |

The format of the TLVs that make up the body of the TE Link Local LSA is the same as that of the TE TLVs: a 2-octet Type field followed by a 2-octet Length field which indicates the length of the Value field in octets. The Top Level Type for the Link Local TLV is 4. The Value field is zero-padded at the end to a four octet boundary.

The only TLV defined here is the Link Local Identifier TLV, with Type 1, Length 4 and Value the 32 bit Link Local Identifier for the link over which the TE Link Local LSA is exchanged.

4. 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
Ciena Corporation
10480 Ridgeview Court
Cupertino, CA 94014

   Phone: +1.408.366.4713
   EMail: greg@ciena.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
Metanoia, Inc.
335 Elan Village Lane, Unit 203
San Jose, CA 95134-2539

   Phone: +1.408.943.1794
   EMail: v.sharma@ieee.org

5. Acknowledgements

The authors would like to thank Suresh Katukam, Jonathan Lang, Quaizar Vohra, and Alex Zinin for their comments on the document.

6. Security Considerations

This document specifies the contents of Opaque LSAs in OSPFv2. As Opaque LSAs are not used for SPF computation or normal routing, the extensions specified here have no direct effect on IP routing. Tampering with GMPLS TE LSAs may have an effect on the underlying transport (optical and/or SONET-SDH) network. [OSPF-TE] suggests mechanisms such as [OSPF-SIG] to protect the transmission of this information, and those or other mechanisms should be used to secure and/or authenticate the information carried in the Opaque LSAs.

7. IANA Considerations

The memo introduces four new sub-TLVs of the TE Link TLV in the TE Opaque LSA for OSPF v2; [OSPF-TE] says that the sub-TLVs of the TE Link TLV in the range 10-32767 must be assigned by Expert Review, and must be registered with IANA.

The memo has four suggested values for the four sub-TLVs of the TE Link TLV; it is strongly recommended that the suggested values be granted, as there are interoperable implementations using these values.

Finally, a new Top Level Type for OSPF TE LSAs for the Link Local TLV has been allocated from the Standards Action space.

8. References

8.1. 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., "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).
   
   [OSPF]          Moy, J., "OSPF Version 2", STD 54, RFC 2328, April
                   1998.
   
   [OSPF-RESTART]  Moy, J., Pillay-Esnault, P., and A. Lindem, "Graceful
                   OSPF Restart", RFC 3623, November 2003.
   
   [OSPF-SIG]      Murphy, S., Badger, M., and B. Wellington, "OSPF with
                   Digital Signatures", RFC 2154, June 1997.
   
   [OSPF-TE]       Katz, D., Kompella, K., and Yeung, D., "Traffic
                   Engineering (TE) Extensions to OSPF Version 2", RFC
                   3630, September 2003.
   
   [RFC2119]       Bradner, S., "Key words for use in RFCs to Indicate
                   Requirement Levels", BCP 14, RFC 2119, March 1997.

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

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