LINK STATE ROUTING PROTOCOLS Dr. Rocky K C Chang 22 November 2010
LINK STATE ROUTING PROTOCOLS Dr. Rocky K. C. Chang 22 November 2010 1
nk state approac o In the dv approach, each router discovers the network topology through the distance vectors received from its neighbors. o In the ls approach each router discovers the network topology through link state advertisements (LSAS) n Each router is responsible for discovering its neighbors and the states of the links between them, and informs other routers a Upon receiving all the link states, a router can form a local view of the entire network
Link state approach 2 In the DV approach, each router discovers the network topology through the distance vectors received from its neighbors. In the LS approach, each router discovers the network topology through link state advertisements (LSAs). Each router is responsible for discovering its neighbors and the states of the links between them, and informs other routers. Upon receiving all the link states, a router can form a local view of the entire network
An example [from [3]) 口R。 outers connected by point-to- point links a Networ ks connected to the routers are omitted a Link states are generally asymmetric 5 A C D E
An example [from [3]) 3 Routers connected by point-to-point links Networks connected to the routers are omitted. Link states are generally asymmetric. A B C E D 4 3 1 1 5 2 3
After exchanging LSAs with neighbors (from [1]) 口 For router a B Link a4 A c Link b4 HA3 C|3 E1 E Link A|1
After exchanging LSAs with neighbors (from [1]) 4 For router A 4 3 1 A Link B C E 4 3 1 E Link A 1 C Link A 3 B Link A 4
After receiving all LSAs(from [1]) 5 o After the protocol converges the routers' link state databases are identical B Link a 4 D 2 A D Link BCE 431 3 ADE B 5 E 253 E C 1 D|3
After receiving all LSAs (from [1]) 5 After the protocol converges, the routers’ link state databases are identical. 4 3 1 1 5 2 3 A Link B C E 4 3 1 E Link A C D 1 1 3 C Link A D E 3 5 1 D Link B C E 2 5 3 B Link A D 4 2