| 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?
| A. |
hello packets | |
| B. |
SAP messages sent by neighbor routers | |
| C. |
LSAs from other routers | |
| D. |
beacons received on point-to-point links | |
| E. |
routing tables received from other link-state routers | |
| F. |
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.