Chapter 7
OSPFv3 Configuration
Table of Contents
7.1 OSPFv3 Overview
Introduction to OSPFv3
Open Shortest Path First (
) version 2 is a link-status-based interior gateway protocol
developed by IETF. Because it has a wide application scope, provides fast convergence,
eliminates routing loops and facilitates hierarchical network design, it has been widely
applied in IPv4 networks.
With the construction of IPv6 networks, dynamic routing protocols are also required to
provide accurate and valid routing information for IPv6 packet forwarding. For this reason,
IETF revised OSPFv2 according to IPv6 networks and developed OSPFv3. OSPFv3 is
mostly used in IPv6 networks to provide the routing function. It is a mainstream routing
protocol applied in IPv6 networks.
The IPv6 OSPF protocol is OSPFv3, and the IPv4 OSPF protocol is OSPFv2.
The IPv6 OSPF keeps the majority of IPv4 algorithms. The essential OSPF mechanism
remains unchanged from IPv4 to IPv6.
Both OSPFv3 and OSPFv2 have a link status database. The Link Status Advertisement
(
) is contained in the link status database, and the link status databases of all routers
in the same area must be kept synchronous.
Database synchronization is implemented through the database exchange process, which
includes exchanging database description packets, link state request packets and link state
update packets. The subsequent database synchronization is maintained through flooding
with link state update packets and link state acknowledgment packets.
In broadcast and Non-Broadcast Multicast Access (
) networks, both OSPFv3 and
OSPFv2 use the hello packet to discover and maintain adjacency and to elect Designate
Router (
) and Backup Designate Router (
).
OSPFv3 and OSPFv2 also keep consistent with each other in such aspects as neighbor
determination, basic concept of inter-area routes, redistribution of Autonomous System
(
) external routes and so on.
7-1
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