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
COMPUTER TIPS