OSPF for IPv6
RFC 5340

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Network Working Group                                          R. Coltun
Request for Comments: 5340                          Acoustra Productions
Obsoletes: 2740                                              D. Ferguson
Category: Standards Track                               Juniper Networks
                                                                  J. Moy
                                                  Sycamore Networks, Inc
                                                          A. Lindem, Ed.
                                                        Redback Networks
                                                               July 2008

                             OSPF for IPv6

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 describes the modifications to OSPF to support version
   6 of the Internet Protocol (IPv6).  The fundamental mechanisms of
   OSPF (flooding, Designated Router (DR) election, area support, Short
   Path First (SPF) calculations, etc.) remain unchanged.  However, some
   changes have been necessary, either due to changes in protocol
   semantics between IPv4 and IPv6, or simply to handle the increased
   address size of IPv6.  These modifications will necessitate
   incrementing the protocol version from version 2 to version 3.  OSPF
   for IPv6 is also referred to as OSPF version 3 (OSPFv3).

   Changes between OSPF for IPv4, OSPF Version 2, and OSPF for IPv6 as
   described herein include the following.  Addressing semantics have
   been removed from OSPF packets and the basic Link State
   Advertisements (LSAs).  New LSAs have been created to carry IPv6
   addresses and prefixes.  OSPF now runs on a per-link basis rather
   than on a per-IP-subnet basis.  Flooding scope for LSAs has been
   generalized.  Authentication has been removed from the OSPF protocol
   and instead relies on IPv6's Authentication Header and Encapsulating
   Security Payload (ESP).

   Even with larger IPv6 addresses, most packets in OSPF for IPv6 are
   almost as compact as those in OSPF for IPv4.  Most fields and packet-
   size limitations present in OSPF for IPv4 have been relaxed.  In
   addition, option handling has been made more flexible.

Coltun, et al.              Standards Track                     [Page 1]
RFC 5340                     OSPF for IPv6                     July 2008

   All of OSPF for IPv4's optional capabilities, including demand
   circuit support and Not-So-Stubby Areas (NSSAs), are also supported
   in OSPF for IPv6.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Requirements Notation  . . . . . . . . . . . . . . . . . .  4
     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Differences from OSPF for IPv4 . . . . . . . . . . . . . . . .  5
     2.1.  Protocol Processing Per-Link, Not Per-Subnet . . . . . . .  5
     2.2.  Removal of Addressing Semantics  . . . . . . . . . . . . .  5
     2.3.  Addition of Flooding Scope . . . . . . . . . . . . . . . .  6
     2.4.  Explicit Support for Multiple Instances per Link . . . . .  6
     2.5.  Use of Link-Local Addresses  . . . . . . . . . . . . . . .  7
     2.6.  Authentication Changes . . . . . . . . . . . . . . . . . .  7
     2.7.  Packet Format Changes  . . . . . . . . . . . . . . . . . .  8
     2.8.  LSA Format Changes . . . . . . . . . . . . . . . . . . . .  9
     2.9.  Handling Unknown LSA Types . . . . . . . . . . . . . . . . 10
     2.10. Stub/NSSA Area Support . . . . . . . . . . . . . . . . . . 11
     2.11. Identifying Neighbors by Router ID . . . . . . . . . . . . 11
   3.  Differences with RFC 2740  . . . . . . . . . . . . . . . . . . 11
     3.1.  Support for Multiple Interfaces on the Same Link . . . . . 11
     3.2.  Deprecation of MOSPF for IPv6  . . . . . . . . . . . . . . 12
     3.3.  NSSA Specification . . . . . . . . . . . . . . . . . . . . 12
     3.4.  Stub Area Unknown LSA Flooding Restriction Deprecated  . . 12
     3.5.  Link LSA Suppression . . . . . . . . . . . . . . . . . . . 12
     3.6.  LSA Options and Prefix Options Updates . . . . . . . . . . 13
     3.7.  IPv6 Site-Local Addresses  . . . . . . . . . . . . . . . . 13
   4.  Implementation Details . . . . . . . . . . . . . . . . . . . . 13
     4.1.  Protocol Data Structures . . . . . . . . . . . . . . . . . 14
       4.1.1.  The Area Data Structure  . . . . . . . . . . . . . . . 15
       4.1.2.  The Interface Data Structure . . . . . . . . . . . . . 15
       4.1.3.  The Neighbor Data Structure  . . . . . . . . . . . . . 16
     4.2.  Protocol Packet Processing . . . . . . . . . . . . . . . . 17