|Exam 200-120||Question id=45||IP Routing Technologies|
What information does a router running a link-state protocol use to maintain and build it's topology database?
SAP messages sent by neighbor routers|
LSAs from other routers|
beacons received on point-to-point links|
routing tables received from other link-state routers|
TTL from multi-hop designated routers|
Link-state routing protocols generate routing updates only when a change occurs in the network topology. When a link changes state, the device that detected the change creates a link-state advertisement (LSA) concerning that link and sends to all neighboring devices using a special multicast address. Each routing device takes a copy of the LSA, updates its link-state database (LSDB), and forwards the LSA to all neighboring devices.
Hello: are used to establish and maintain adjacency with other OSPF routers. They are also used to elect the Designated Router (DR) and Backup Designated Router (BDR) on multiaccess networks.