The OSPF Opaque LSA Option
RFC 2370

Network Working Group                                          R. Coltun
Request for Comments: 2370                                  FORE Systems
See Also: 2328                                                 July 1998
Category: Standards Track

                       The OSPF Opaque LSA Option

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

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

Table Of Contents

   1.0 Abstract .................................................  1
   2.0 Overview .................................................  2
   2.1 Organization Of This Document ............................  2
   2.2 Acknowledgments ..........................................  3
   3.0 The Opaque LSA ...........................................  3
   3.1 Flooding Opaque LSAs .....................................  4
   3.2 Modifications To The Neighbor State Machine ..............  5
   4.0 Protocol Data Structures .................................  6
   4.1 Additions To The OSPF Neighbor Structure .................  6
   5.0 Management Considerations ................................  7
   6.0 Security Considerations ..................................  9
   7.0 IANA Considerations ...................................... 10
   8.0 References ............................................... 10
   9.0 Author's Information ..................................... 11
   Appendix A: OSPF Data Formats ................................ 12
   A.1 The Options Field ........................................ 12
   A.2 The Opaque LSA ........................................... 13
   Appendix B: Full Copyright Statment .......................... 15

1.0  Abstract

   This memo defines enhancements to the OSPF protocol to support a new
   class of link-state advertisements (LSA) called Opaque LSAs.  Opaque
   LSAs provide a generalized mechanism to allow for the future
   extensibility of OSPF. Opaque LSAs consist of a standard LSA header
   followed by application-specific information.  The information field

Coltun                      Standards Track                     [Page 1]
RFC 2370               The OSPF Opaque LSA Option              July 1998

   may be used directly by OSPF or by other applications.  Standard OSPF
   link-state database flooding mechanisms are used to distribute Opaque
   LSAs to all or some limited portion of the OSPF topology.

2.0  Overview

   Over the last several years the OSPF routing protocol [OSPF] has been
   widely deployed throughout the Internet.  As a result of this
   deployment and the evolution of networking technology, OSPF has been
   extended to support many options; this evolution will obviously
   continue.

   This memo defines enhancements to the OSPF protocol to support a new
   class of link-state advertisements (LSA) called Opaque LSAs.  Opaque
   LSAs provide a generalized mechanism to allow for the future
   extensibility of OSPF. The information contained in Opaque LSAs may
   be used directly by OSPF or indirectly by some application wishing to
   distribute information throughout the OSPF domain.  For example, the
   OSPF LSA may be used by routers to distribute IP to link-layer
   address resolution information (see [ARA] for more information).  The
   exact use of Opaque LSAs is beyond the scope of this memo.

   Opaque LSAs consist of a standard LSA header followed by a 32-bit
   qaligned application-specific information field.  Like any other LSA,
   the Opaque LSA uses the link-state database distribution mechanism
   for flooding this information throughout the topology.  The link-
   state type field of the Opaque LSA identifies the LSA's range of
   topological distribution. This range is referred to as the Flooding
   Scope.

   It is envisioned that an implementation of the Opaque option provides
   an application interface for 1) encapsulating application-specific
   information in a specific Opaque type, 2) sending and receiving
   application-specific information, and 3) if required, informing the
   application of the change in validity of previously received
   information when topological changes are detected.

2.1  Organization Of This Document

   This document first defines the three types of Opaque LSAs followed
   by a description of OSPF packet processing. The packet processing
   sections include modifications to the flooding procedure and to the
   neighbor state machine. Appendix A then gives the packet formats.