COMPUTER TIPS

How to configure IS-IS protocol using Cisco routers?

 

 

IS-IS short for Intermediate System-to-Intermediate System is a routing Protocol used to exchange information between level 1 routing devices. IS-IS was developed by Digital Equipment Corporation and uses the Dijkstra’s algorithm to select the best suitable route for packets with in the network. It is a link state routing protocols and perform many functions, for example fast convergence, scalable nature, classless behavior, work with multi-area routing and also support routing leaking.

Today tip will help you to configure IS-IS routing protocols between two different types of areas. In this case, we will try to configure three different routers with routing protocols IS-IS & set the router levels manually using is-type level-1 or is-type level-2 command.

Follow the network topology of three different class network in given figure:

 

IS-IS configuration on Router A

In global configuration mode

Router-A(config) # router isis  (Here enable ISIS protocols on router A)

Router-A(config-Router) # net 49.0001.00b0.6484.4f10.00 (Here 00b0.6484.4f10 indicate the system ID and 1 is area number) 

Router-A(config-Router) # is-type level-1 (set the level for router A) 

Router-A(config-Router) #exit

Router-A(config)# interface serial 0

Router-A(config-if)# ip router isis

Router-A(config-if) #exit

Router-A(config)# interface ethernet 0

Router-A(config-if)# ip router isis

Router-A(config-if) #exit 

IS-IS configuration on Router B

In global configuration mode  

Router-B(config) # router isis  (Here enable ISIS protocols on router B)

Router-B(config-Router) # net 49.0001.00b0.3233.4f10.00 (Here 00b0.3233.4f10 indicate the system ID and 1 is area number) 

Router-B(config-Router) #exit

Router-B(config)# interface serial 0

Router-B(config-if)# ip router isis

Router-B(config-if) #exit

Router-B(config)# interface serial 1

Router-B(config-if)# ip router isis

Router-B(config-if) #exit

Router-B(config)# interface ethernet 0

Router-B(config-if)# ip router isis

Router-B(config-if) #exit

IS-IS configuration on Router C

In global configuration mode  

Router-C(config) # router isis  (Here enable ISIS protocols on router C)

Router-C(config-Router) # net 49.0002.00c0.0050.4f10.00 (Here 00c0.0050.4f10 indicate the system ID and 2 is area number) 

Router-C(config-Router) # is-type level-2 (set the level for router C) 

Router-C(config-Router) #exit

Router-C(config)# interface serial 1

Router-C(config-if)# ip router isis

Router-C(config-if) #exit

Router-C(config)# interface ethernet 0

Router-C(config-if)# ip router isis

Router-C(config-if) #exit

Now verify the routes in router A routing table, run the command:

Router-A# show ip route

      

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