Changing the Router from Level 1-2
By default, routers support both Level 1 and Level 2 routing. Routing at both levels means twice as many hellos and advertisements, twice as much memory consumed, and twice as much processing. However, routing at both levels makes configuration easier. One easy way to optimize IS-IS is to reduce the unnecessary duplication of routing at both levels. IS-IS level is set under the IS-IS process using the is-type level-1 or is-type level-2 commands. Once applied, all interfaces c..
Maintaining the Topology Table
The topology table may be recalculated because a new network is added to the network, successors change, or because a network is lost. Figure 3-4 illustrates the traffic flow seen when a router loses a connection. Figure 3-4. Traffic Flow Used to Maintain the Topology Table Just as the neighbor table tracks the receipt of the EIGRP packets, the topology table records the packets that have been sent by the router to the neighbors. It also identifies the status of the ..
Level 1 router summarization is done only for external routes (redistributed routes from other protocols) because the level 1 router does not receive any routes from the level 2 routers. As such, there is no need to summarize routes from level 2 routers—you can summarize both level 1 and external routes in level 2. External routes can be summarized only at the redistributing router. After the LSP is originated, it cannot be summarized. Summarizing of external ..
Setting the Source Address for Telnet
To configure a single common IP source address for all outbound Telnet session, use the following configuration command: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z.Router1(config)#ip telnet source-interface loopback0Router1(config)#endRouter1# You can also set the IP source address for individual outbound Telnet sessions on the command line: Router1#telnet 172.25.1.5 /source-interface loopback0 By default, the router uses the ..
You can improve the convergence time of OSPF on a particular interface by reducing the hello and dead timers: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#interface Serial0/1 Router1(config-if)#ip ospf hello-interval 5 Router1(config-if)#ip ospf dead-interval 20 Router1(config-if)#exit Router1(config)#end Router1# If you make this change on one router, you must make it on all of the other routers sharing the..
