The OSPF Opaque LSA Option
RFC 5250

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Network Working Group                                          L. Berger
Request for Comments: 5250                                          LabN
Obsoletes: 2370                                               I. Bryskin
Category: Standards Track                                           Adva
                                                                A. Zinin
                                                          Alcatel-Lucent
                                                               R. Coltun
                                                    Acoustra Productions
                                                               July 2008

                       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.

Abstract

   This document defines enhancements to the OSPF protocol to support a
   new class of link state advertisements (LSAs) 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
   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.

   This document replaces RFC 2370 and adds to it a mechanism to enable
   an OSPF router to validate Autonomous System (AS)-scope Opaque LSAs
   originated outside of the router's OSPF area.

Berger, et al.              Standards Track                     [Page 1]
RFC 5250                 OSPF Opaque LSA Option                July 2008

Table of Contents

   1. Introduction ....................................................3
      1.1. Organization of This Document ..............................3
      1.2. Acknowledgments ............................................3
   2. Conventions Used in This Document ...............................4
   3. The Opaque LSA ..................................................4
      3.1. Flooding Opaque LSAs .......................................5
      3.2. Modifications to the Neighbor State Machine ................6
   4. Protocol Data Structures ........................................7
      4.1. Additions to the OSPF Neighbor Structure ...................8
   5. Inter-Area Considerations .......................................8
   6. Management Considerations .......................................9
   7. Backward Compatibility ..........................................9
   8. Security Considerations .........................................9
   9. IANA Considerations ............................................11
   10. References ....................................................12
      10.1. Normative References .....................................12
      10.2. Informative References ...................................12
   Appendix A. OSPF Data formats .....................................13
      A.1. The Options Field .........................................13
      A.2. The Opaque LSA ............................................14

Berger, et al.              Standards Track                     [Page 2]
RFC 5250                 OSPF Opaque LSA Option                July 2008

1.  Introduction

   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 document defines enhancements to the OSPF protocol to support a
   new class of link state advertisements (LSAs) 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.  The exact use of
   Opaque LSAs is beyond the scope of this document.

   Opaque LSAs consist of a standard LSA header followed by a 32-bit
   aligned 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