OSPFv3 and OSPFv2 Similarities

• OSPFv3 uses the same 5 message types, with the same message numbering, as OSPFv2:
  • 1 – Hello
  • 2 – Database Description
  • 3 – Link-State database Request
  • 4 – Link-State Database Update
  • 5 – Link-State Database Acknowledgment

    Keep in mind that OSPFv3 message header fields differ in that there:

  • Are no fields for authentication
  • Is an instance ID field that has local link significance only
• OSPFv2 and OSPv3 support multiple OSPF processes on a device.
• The mechanisms for neighbor discovery and adjacency formation have not changed.
• The supported interface types point-to-point, point-to-mulitpoint, broadcast, NBMA, and virtual have not changed.
• LSA flooding and aging have not changed.
• All of OSPFv2 optional capabilities, including on-demand circuit support, NSSA areas, and the multicast extensions to OSPF are supported in OSPFv3.
• Area ID and Router ID remain 32 bit identifiers. Areas can be configured for Not-So-Stubby-Area (NSSA), Stub Area, and virtual-links.