OSPFv3 adds support for IPv6 in the OSPF routing protocol, as described in RFC 2740. Most configurations and operational commands function essentially the same in OSPFv3 as they do in OSPFv2. For example, OSPFv3 router IDs, area IDs, and LSA link state IDs are 32 bits, just as they are in OSPFv2 IPv4. In addition, all of the optional capabilities of OSPFv2 for IPv4, for example, NSSA, are supported in OSPFv3 for IPv6.
However, there are also many significant changes in OSPFv3 for IPv6, including the following:
Router LSAs and network LSAs no longer carry prefix information. In OSPFv3, these LSAs carry only the topology information.
New and modified LSAs have been created to handle the flow of IPv6 addresses and prefixes in an OSPFv3 network.
OSPFv3 runs on a per-link basis, instead of a per-IP-subnet basis.
IPv6 link-local addresses are used for OSPFv3 neighbor exchanges, except over virtual links.
The flooding scope for LSAs is generalized into three categories for OSPFv3:
Link-local scope. The OSPFv3 packet is flooded only to the members connected on a link.
Area scope. The OSPFv3 packet is flooded to all members of an OSPFv3 area.
AS scope. The OSPFv3 packet is flooded to all members of an AS.
Authentication is removed from the OSPFv3 protocol. Instead, OSPFv3 relies on the AH and ESP portions of the IPSec for all authentication tasks in IPv6.
LSPs and traffic engineering are not supported in OSPFv3.
The 32-bit router ID in OSPFv3 always identifies neighboring routers.