What is OSPFv3?
OSPFv3 is a link-state routing protocol for IPv6 as its predecessor OSPFv2 in IPv4.
OSPFv3 still uses the autonomous areas to separate networks into areas.
OSPFv3 uses an IPv6 multicast address range of FF02::5 for OSPF routes and FF02::6 for ospf designated routers when sending updates and acknowledgments.
OSPF routers generate routing updates only when a change occurs in the network topology.
When a route link changes state, the network device that detects the change creates a Link State Advertisement (LSA) and forwards it to the DR using FF02::6 multicast address who informs all devices within an area using FF02::5 multicast address. Each device then updates its Link State Database.
One of the new features of OSPFv3 is the ability to assign the router ID, area ID and link-state ID with a 32-bit value without IP addresses. This feature enables OSPFv3 to be routable over almost any network layer protocol. Like other IPv6 routing protocols – RIPng and EIGRPv6, you must enable it directly on the router interface for the process to work.
OSPFv3 Configuration Requirements.
* Enable IPv6 unicast routing
* Enable the OSPFv3 routing process
* Enable OSPFv3 on the interface
* Configure passive interfaces to suppress routing updates to and from an interface.
The biggest differences between OSPFv3 and the older OSPFv2 lay with internals and with configuration. OSPFv3 changes the structure of some OSPF LSAs and uses a more direct approach to configuration, enabling OSPFv3 on each interface using an interface subcommand.
The interface configuration process is just to assign an ospfv3 process ID and area.
Similarities between OSPFv2 and OSPFv3
√ Both are link-state protocols.
√ Both use the same area design concepts and design terms.
√ Both require that the routing protocol is enabled on an interface.
√ Once enabled on an interface, both then attempt to discover neighbors connected to the data link connected to an interface.
√ Both perform a check of certain settings before a router will become neighbors with another router (the list of checks is slightly different between OSPFv2 and OSPFv3).
√ After two routers become neighbors, both OSPFv2 and OSPFv3 proceed by exchanging the contents of their link-state databases (LSDB)—the link-state advertisements (LSA) that describe the network topology—between the two neighbors.
√ After all the LSAs have been exchanged, both OSPFv2 and OSPFv3 use the shortest path first (SPF) algorithm to calculate the best route to each subnet.
√ Both use the same metric concept, based on the interface cost of each interface, with the same default cost values.
√ Both use LSAs to describe the topology, with some differences in how LSAs work.