Misconfiguration

Misconfiguration leads to disruption of routing communication between RIP-enabled routers. In addition, it impedes the advertising and receiving of valid routing updates between the routers. Following are the various possible areas pertaining to misconfiguration that may require troubleshooting in RIP environments:

• Network command misconfiguration

• Active VLSM subnets in the network topology

• Missing/incorrect network statement

• Inactive interfaces

• Distribute list out is blocking the routes

• Advertised network interface is down

• Outgoing interface is defined as passive

• Neighbor statement misconfiguration

• Split-horizon is enabled

Consider a scenario in which four routers Router1, Router2, Router3, and Router4 are connected, as shown in Figure 6.1.

Figure 6.1: A routing scenario with four interconnected routers.

The scenario depicted in Figure 6.1 will be used to troubleshoot different problems as discussed in the following sections.

The output of the command router rip from all the four routers used in Figure 6.1 is displayed in the following code listings. Listing 6.4 shows the output of the command router rip from Router1.

Listing 6.4 Output of the Command router rip from Router1

Router1#conf t Router1(global)#interface fa0/0 Router1(global-if)#ip address 192.168.1.2 255.255.255.0 Router1(global-if)#no shut Router1(global)#interface loopback 1 Router1(global-if)#ip address 11.0.1.1 255.255.255.0 Router1(global)#interface loopback 2 Router1(global-if)#ip address 11.0.2.1 255.255.255.0 Router1(global-if)#exit Router1(global)# router rip Router1(global-router)#network 192.168.1.0 Router1(global-router)#network 11.0.0.0

Listing 6.5 shows the output of the command router rip from Router2.

Listing 6.5 Output of the Command router rip from Router2

Router2#conf t Router2(global)#interface fa0/0 Router2(global-if)#ip address 192.168.1.1 255.255.255.0 Router2(global-if)#no shut Router2(global)#interface fa0/1 Router2(global-if)#ip address 192.168.2.1 255.255.255.0 Router2(global-if)#no shut Router2(global-if)#exit Router2(global)# router rip Router2(global-router)#network 192.168.1.0 Router2(global-router)#network 192.168.2.0

Listing 6.6 shows the output of the command router rip from Router3.

Listing 6.6 Output of the Command router rip from Router3

Router3#conf t Router3(global)#interface fa0/0 Router3(global-if)#ip address 192.168.2.2 255.255.255.0 Router3(global-if)#no shut Router3(global)#interface loopback 1 Router3(global-if)#ip address 10.0.1.1 255.255.255.0 Router3(global)#interface loopback 2 Router3(global-if)#ip address 10.0.2.1 255.255.255.0 Router3(global)#interface loopback 3 Router3(global-if)#ip address 10.0.3.1 255.255.255.0 Router3(global)#interface fa0/1 Router3(global-if)#ip address 10.0.4.1 255.255.255.0 Router3(global-if)#no shut Router3(global-if)#exit Router3(global)# router rip Router3(global-router)#network 192.168.2.0 Router3(global-router)#network 10.0.0.0

Listing 6.7 shows the output of the command router rip from Router4.

Listing 6.7 Output of the Command router rip from Router4

Router4#conf t Router4(global)#interface fa0/0 Router4(global-if)#ip address 10.0.4.2 255.255.255.0 Router4(global-if)#no shut Router4(global)#interface loopback 1 Router4(global-if)#ip address 10.0.5.1 255.255.255.0 Router4(global-if)#exit Router4(global)# router rip Router4(global-router)#network 10.0.0.0

The output of the command show ip protocols from all the four routers used in Figure 6.1 is listed in the following listings. Listing 6.8 shows the output of the command show ip protocols from Router1.

Listing 6.8 Output of the Command show ip protocols from Router1

Router1#sh ip protocols Routing Protocol is "rip"   Sending updates every 30 seconds, next due in 21 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Outgoing update filter list for all interfaces is   Incoming update filter list for all interfaces is   Redistributing:   rip   Default version control: send version 1, receive any version     Interface        Send  Recv   Key-chain     FastEthernet0      1    1 2   Routing for Networks:     192.168.1.0     11.0.0.0   Routing Information Sources:     192.168.1.1           120      00:00:0   Distance: (default is 120)

Listing 6.9 shows the output of the command show ip protocols from Router2.

Listing 6.9 Output of the Command show ip protocols from Router2

Router2#sh ip protocols Routing Protocol is "rip"   Sending updates every 30 seconds, next due in 31 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Outgoing update filter list for all interfaces is   Incoming update filter list for all interfaces is   Redistributing:   rip   Default version control: send version 1, receive any version     Interface        Send  Recv   Key-chain     FastEthernet0      1    1 2     FastEthernet0      1    1 2   Routing for Networks:     192.168.1.0     192.168.2.0   Routing Information Sources:     192.168.1.2           120      00:00:03     192.168.2.2           120      00:00:06   Distance: (default is 120)

Listing 6.10 shows the output of the command show ip protocols from Router3.

Listing 6.10 Output of the Command show ip protocols from Router3

Router3#sh ip protocols Routing Protocol is "rip"   Sending updates every 30 seconds, next due in 19 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Outgoing update filter list for all interfaces is   Incoming update filter list for all interfaces is   Redistributing:   rip   Default version control: send version 1, receive any version     Interface        Send  Recv   Key-chain     FastEthernet0      1    1 2     FastEthernet0      1    1 2   Routing for Networks:     10.0.0.0     192.168.2.0   Routing Information Sources:     192.168.2.1           120      00:00:09     10.0.4.2              120      00:00:09   Distance: (default is 120)

Listing 6.11 shows the output of the command show ip protocols from Router4.

Listing 6.11 Output of the Command show ip protocols from Router4

Router4#sh ip protocols Routing Protocol is "rip"   Sending updates every 30 seconds, next due in 22 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Outgoing update filter list for all interfaces is   Incoming update filter list for all interfaces is   Redistributing:   rip   Default version control: send version 1, receive any version     Interface        Send  Recv   Key-chain     FastEthernet0      1    1 2   Routing for Networks:     10.0.0.0   Routing Information Sources:     10.0.4.1              120      00:00:09 Distance: (default is 120)

The command to view the routing table of a router is show ip route.

The output of the command show ip route for all the four routers as given in Figure 6.1 is listed in the following listings. Listing 6.12 shows the output of the command show ip route from Router1.

Listing 6.12 Output of the Command show ip route from Router1

Router1#sh 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        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 Gateway of last resort is not set   C  11.0.1.0/24 is directly connected, Loopback1   C  192.168.1.0/24 is directly connected, FastEthernet0/0   C  11.0.2.0/24 is directly connected, Loopback2   R  192.168.2.0/24 [120/1] via 192.168.1.1, 00:06:29, FastEthernet0/0   R  10.0.1.0/24 [120/2] via 192.168.1.1, 00:08:29, FastEthernet0/0   R  10.0.2.0/24 [120/2] via 192.168.1.1, 00:03:36, FastEthernet0/0   R  10.0.3.0/24 [120/2] via 192.168.1.1, 00:02:15, FastEthernet0/0   R  10.0.4.0/24 [120/2] via 192.168.1.1, 00:06:23, FastEthernet0/0   R  10.0.5.0/24 [120/3] via 192.168.1.1, 00:02:43, FastEthernet0/0

Listing 6.13 shows the output of the command show ip route from Router2.

Listing 6.13 Output of the Command show ip route from Router2

Router2#sh 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        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 Gateway of last resort is not set   C  192.168.1.0/24 is directly connected, FastEthernet0/0   C  192.168.2.0/24 is directly connected, FastEthernet0/1   R  11.0.1.0/24 [120/1] via 192.168.1.2, 00:08:20, FastEthernet0/0   R  11.0.2.0/24 [120/1] via 192.168.1.2, 00:01:42, FastEthernet0/0   R  10.0.1.0/24 [120/1] via 192.168.2.2, 00:02:22, FastEthernet0/1   R  10.0.2.0/24 [120/1] via 192.168.2.2, 00:01:24, FastEthernet0/1   R  10.0.3.0/24 [120/1] via 192.168.2.2, 00:07:38, FastEthernet0/1   R  10.0.4.0/24 [120/1] via 192.168.2.2, 00:03:43, FastEthernet0/1   R  10.0.5.0/24 [120/2] via 192.168.2.2, 00:07:25, FastEthernet0/1

Listing 6.14 shows the output of the command show ip route from Router3.

Listing 6.14 Output of the Command show ip route from Router3

Router3#sh 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        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 Gateway of last resort is not set   C  10.0.1.0/24 is directly connected, Loopback1   C  10.0.2.0/24 is directly connected, Loopback2   C  10.0.3.0/24 is directly connected, Loopback3   C  192.168.2.0/24 is directly connected, FastEthernet0/0   C  10.0.4.0/24 is directly connected, FastEthernet0/1   R  192.168.1.0/24 [120/1] via 192.168.2.1, 00:07:44, FastEthernet0/0   R  10.0.5.0/24 [120/1] via 10.0.4.2, 00:01:14, FastEthernet0/1   R  11.0.1.0/24 [120/2] via 192.168.2.1, 00:07:44, FastEthernet0/0   R  11.0.2.0/24 [120/2] via 192.168.2.1, 00:09:26, FastEthernet0/0

Listing 6.15 shows the output of the command show ip route from Router4.

Listing 6.15 Output of the Command show ip route from Router4

Router4#sh 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        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 Gateway of last resort is not set   C  10.0.5.0/24 is directly connected, Loopback1   C  10.0.4.0/24 is directly connected, FastEthernet0/0   R  10.0.1.0/24 [120/1] via 10.0.4.1, 00:01:32, FastEthernet0/0   R  10.0.2.0/24 [120/1] via 10.0.4.1, 00:02:27, FastEthernet0/0   R  10.0.3.0/24 [120/1] via 10.0.4.1, 00:07:35, FastEthernet0/0   R  192.168.2.0/24 [120/1] via 10.0.4.1, 00:05:40, FastEthernet0/0   R  192.168.1.0/24 [120/2] via 10.0.4.1, 00:07:17, FastEthernet0/0   R  11.0.1.0/24 [120/3] via 10.0.4.1, 00:01:24, FastEthernet0/0   R  11.0.2.0/24 [120/3] via 10.0.4.1, 00:09:35, FastEthernet0/0