OSPF routers communicate with each other by using the various subprotocols with the OSPF protocol. OSPF runs on top of IP, although OSPF is composed of the following subprotocols:
The following sections discuss these subprotocols in detail.
OSPF uses five different packets in its protocols. Table 3-2 describes the different OSPF packet types. This section discusses each protocol and the role that the packets play.
|Hello||1||Discovers and maintains neighbors.|
|Database description||2||Summarizes database contents.|
|Link state request||3||Requests LSAs that need to be downloaded to requesting router. Only sent during Exchange, Loading, ...|