OSPFv3

OSPFv3 is the IPv6-enabled version of the Open Shortest Path First (OSPF) routing protocol. Defined in RFC 5340, it serves as a link-state interior gateway protocol for IPv6 networks, computing shortest-path trees and distributing routing information within an autonomous system.

Like OSPFv2, OSPFv3 uses areas, router LSAs, network LSAs, and summary and ASBR LSAs to form a consistent topology database and compute routes with the SPF algorithm. It can run multiple routing instances on a single link via an instance ID, allowing network segmentation similar to VRFs.

OSPFv3 introduces IPv6-specific enhancements, including new link-state advertisements for IPv6 link properties and prefixes. It uses IPv6 addresses and prefixes in LSAs, and neighbor adjacencies are formed over IPv6 link-local addresses with IPv6 multicast for the protocol's discovery and flooding processes.

Security is primarily provided by IPsec; traditional OSPFv2-style password authentication is not used. OSPFv3 supports redistribution and filtering of routes between instances or other routing protocols, as in OSPFv2, with considerations for IPv6.

OSPFv3 is widely implemented by major vendors and is commonly deployed in enterprises and service-provider networks that run IPv6. It can operate in dual-stack environments alongside OSPFv2, though careful planning is required for area design, route redistribution, and inter-area summarization.