Static Routing and Distance Vector Routing Protocols - CCIE Routing and Switching Exam Certification Guide - page 341

Example 7-20 shows the configuration for Router10. IGRP 100 is enabled with the router igrp
100 command. The network 172.16.0.0 specifies that all interfaces on this router with an IP
address within 172.16.0.0 are part of the IGRP process.

Example 7-20 IGRP Configuration for Router10

hostname Router10
!
interface Ethernet0
ip address 172.16.2.1 255.255.255.0
!
interface Serial0
ip address 172.16.4.2 255.255.255.0
!
router igrp 100
network 172.16.0.0

You can verify the routes by using the show ip route command. In Example 7-21, the IGRP
routes are labeled with an I. For Router8, network 172.16.4.0 has an IGRP metric of 8576, and
for network 172.16.2.0, the IGRP metric is 8676. The administrative distance for IGRP is 100,
which is the number that accompanies the IGRP metric in the brackets.

Example 7-21 Output for show ip route on Router8

Router8#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, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

I - IGRP

Gateway of last resort is not set

172.16.0.0/24 is subnetted, 4 subnets
I 172.16.4.0 [100/8576] via 172.16.1.1, 00:00:32, Ethernet0
C 172.16.1.0 is directly connected, Ethernet0
I 172.16.2.0 [100/8676] via 172.16.1.1, 00:00:32, Ethernet0
C 172.16.3.0 is directly connected, TokenRing0

The output of the show ip route command from Router9 is shown in Example 7-22. For
Router9, network 172.16.2.0 has an IGRP metric of 8576 through the serial interface, and for
network 172.16.3.0 the IGRP metric is 1163 through the Ethernet interface.