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
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