Route Information Gateway

Route Information
Just like with other routing protocols, you should always verify that the correct information is
in the routing table:
RouterB#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
i L1 192.168.50.0/24 [115/20] via 192.168.40.1, Serial1.1
i L2 192.168.1.0/24 [115/40] via 192.168.30.2, Serial0.1
i L2 192.168.10.0/24 [115/30] via 192.168.30.2, Serial0.1
i L2 192.168.20.0/24 [115/20] via 192.168.30.2, Serial0.1
C 192.168.40.0/24 is directly connected, Serial1.1
C 192.168.30.0/24 is directly connected, Serial0.1
As can be seen from this routing table, there is one Level 1 route and three Level 2 routes that
were learned through IS-IS. You know that a route is a Level 1 IS-IS route by the code L1, and
you recognize a Level 2 IS-IS route by the code L2. The code I at the beginning of the line means
226 Chapter 7  Integrated IS-IS
that the route is an IS-IS route. If you would like to view only routes learned by IS-IS, the following
command may be used:
RouterB#show ip route isis
i L1 192.168.50.0/24 [115/20] via 192.168.40.1, Serial1.1
i L2 192.168.1.0/24 [115/40] via 192.168.30.2, Serial0.1
i L2 192.168.10.0/24 [115/30] via 192.168.30.2, Serial0.1
i L2 192.168.20.0/24 [115/20] via 192.168.30.2, Serial0.1