How OSPF for IPv6 Works

OSPF is a routing protocol for IP. It is a link-state protocol, as opposed to a distance vector protocol. Think of a link as being an interface on a networking device. A link-state protocol makes its routing decisions based on the states of the links that connect source and destination machines.

The state of a link is a description of that interface and its relationship to its neighboring networking devices. The interface information includes the IPv6 prefix of the interface, the network mask, the type of network that it is connected to, the routers connected to that network, and so on.

This information is propagated in various types of link-state advertisements (LSAs). A collection of LSA data on a router is stored in a link-state database (LSDB). The contents of the database, when subjected to Dijkstra's algorithm, result in the creation of the OSPF routing table.

The difference between the database and the routing table is that the database contains a complete collection of raw data; the routing table contains a list of shortest paths to known destinations via specific router interface ports.

OSPFv3, which is described in RFC 2740, supports IPv6.

© 2006 Cisco Systems, Inc. Implementing IPv6 8-43

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