OSPF v3 Overview

OSPF v3 is a redesign of OSPF v2 which adds support for a generic address family. Up to now, only the IPv6 address family has been defined. The OSPF v3 protocol is first described in RFC 2740. It inherits most of the OSPF v2 mechanisms (Flooding, DR, LSU,…) with little changes.

In OSPF v3, router-id has the same format as OSPF v2, new and modified LSAs have been created to handle the flow of IPv6 addresses and prefixes in an OSPF v3 network. The new LSAs introduced in OSPF v3 are the Link LSA, and the Intra-Area-Prefix LSA.

To get more information about OSPF v2, please look at the following reference OSPF v2.

OSPF v3 terminology

Most of the acronyms used for OSPF v3 are common with OSPF v2. More information at following link OSPF v2 terminology.

OSPF v3 packets

OSPF v3 operates over IP protocol number 89, like with IPv4. Also, hello messages are carried over ff02:5. Similarly, ff02:6 is used for messages to DR and BDR

All basic OSPF packet types can be found on OSPF v3 too. It is worth to be noted that LSA of OSPF v2 can be found on OSPF v3.

There are however some specificities:

  • The link state type values are different. Router LSA type id is 0x2001 ( formerly 1 in OSPF v2). Network LSA value is 0x2002, inter-Area Prefix LSA is 0x2003 (formerly network summary LSA type 3), inter-Area Router LSA is 0x2004 (formerly ASBR summary LSA type 4), AS-external LSA type id is 0x4005 (formerly type 5), Group Membership LSA tpye id is 0x2006 (formerly type 6), Type-7 LSA type id is 0x2007 (formerly NSSA external LSA).
  • A new link state type is available : Link LSA type id is 0x0008. This message is dedicated to local link information only.
  • Another link state type is available : The Intra-area Prefix LSA with type id value set to 0x2009. That message is used to carry intra-area network information previously included in Network LSA used with SPF calculation. This separation permits adding or removing IP subnets without modifying the SPF tree.

RFC

RFC 5340:
OSPF version 3