24-Port Layer 3 Switch Management Guide

IP R

OUTING

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OSPF routers exist; as well as the not-so-stubby area option

(RFC 1587).

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.

backbone

normal

area

NSSA

isolated

area

stub

Autonomous System A

Autonomous System B

external network

Router

ABR

ASBR

virtual

link