IP ROUTING

OSPF routers exist; as well as the not-so-stubby area option (RFC 1587).

stub

ABR

ABR

NSSA

backbone

ABR

isolated area

ABR

virtual link

normal area

ASBR

ASBR

Autonomous System A

ASBR

Router

external network

Autonomous System B

Command Usage

OSPF looks at more than just the simple hop count. When adding the shortest path to any node into the tree, the optimal path is chosen on the basis of delay, throughput and connectivity. OSPF utilizes IP multicast to reduce the amount of routing traffic required when sending or receiving routing path updates. The separate routing area scheme used by OSPF further reduces the amount of routing traffic, and thus inherently provides another level of routing protection. In addition, all routing protocol exchanges can be authenticated. Finally, the OSPF algorithms have been tailored for efficient operation in TCP/IP Internets.

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SMC Networks SMC6724L3 manual 187, Command Usage