Overview
OSPFv3 and OSPFv2 have the following in common:
32-bit router ID and area ID.
Hello, Database Description (DD), Link State Request (LSR), Link State Update (LSU), Link State Acknowledgment (LSAck).
Mechanisms for finding neighbors and establishing adjacencies.
Mechanisms for advertising and aging LSAs.
OSPFv3 and OSPFv2 have the following differences:
OSPFv3 runs on a per-link basis. OSPFv2 runs on a per-IP-subnet basis.
OSPFv3 supports running multiple processes on an interface, but OSPFv2 does not support.
OSPFv3 identifies neighbors by router ID. OSPFv2 identifies neighbors by IP address.