Troubleshooting Routing Information Protocol (RIP)
Commands that you can use to gather information about the Routing Information Protocol (RIP) routing protocol in order to assist in your troubleshooting and problem resolution are covered.
Getting network information
To start this process, look at the ip route command, which in addition to listing routes, can display summary information letting you know how many RIP-based networks exist in the routing table.
Router2>enable Password: Router2#show ip route summary IP routing table name is Default-IP-Routing-Table(0) IP routing table maximum-paths is 16 Route Source Networks Subnets Overhead Memory (bytes) connected 2 0 144 272 static 1 0 72 136 rip 1 0 72 136 Total 4 0 288 544
To ensure that the routing protocol is up and functioning, use the show ip protocols command, which provides similar output to the following. However, first note some important things to look for in the output:
Timers and when the next update will be sent to neighboring routers
Version of RIP in use
Interfaces in use for RIP
Networks being routed by RIP
Address from which you are receiving RIP information
Router2>enable Password: Router2#show ip protocols Routing Protocol is "rip" Sending updates every 30 seconds, next due in 12 seconds Invalid after 180 seconds, hold down 180, flushed after 240 Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Redistributing: rip Default version control: send version 2, receive version 2 Interface Send Recv Triggered RIP Key-chain FastEthernet0/0 2 2 FastEthernet0/1 2 2 Automatic network summarization is not in effect Maximum path: 4 Routing for Networks: 192.168.1.0 192.168.5.0 Routing Information Sources: Gateway Distance Last Update 192.168.1.1 120 00:32:42 Distance: (default is 120)
Note the last item, which lists the administrative distance. This point becomes important when using multiple routing protocols, because each protocol has a different default distance that determines which routing protocol is favored when a remote network is advertised on multiple routing protocols.
Seeing information RIP receives
You can view the contents of the RIP database to find out what information RIP has received. Doing so shows you the networks that are part of RIP, the summarization settings, and from which routers your router has learned routes.
Router2>enable Password: Router2#show ip rip database 192.168.1.0/24 auto-summary 192.168.1.0/24 directly connected, FastEthernet0/0 192.168.5.0/24 auto-summary 192.168.5.0/24 directly connected, FastEthernet0/1 192.168.10.0/24 auto-summary 192.168.10.0/24  via 192.168.1.1, 00:00:20, FastEthernet0/0
Finally, you have the system debug command. In regard to RIP, the debug command is limited to database changes. In the following output, you see the types of data you can get from debug command, which are also listed here:
The RIP information your router is sending out and the networks included in the update
The RIP version being used
The RIP data being received, including the interface it arrived on, the router it came from, and the networks that are included
If you are using debug through a remote console, you use terminal monitor to see the debug information the remote console's screen.
Router2>enable Password: Router2#debug ip rip ? database RIP database events events RIP protocol events trigger RIP trigger extension <cr> Router2#debug ip rip RIP protocol debugging is on Router2# *Mar 17 22:57:39.842: RIP: sending v1 update to 255.255.255.255 via FastEthernet0/1 (192.168.5.1) *Mar 17 22:57:39.842: RIP: build update entries *Mar 17 22:57:39.842: network 192.168.1.0 metric 1 *Mar 17 22:57:39.842: network 192.168.10.0 metric 2 *Mar 17 22:57:46.870: RIP: sending v1 update to 255.255.255.255 via FastEthernet0/0 (192.168.1.240) *Mar 17 22:57:46.870: RIP: build update entries *Mar 17 22:57:46.870: network 192.168.5.0 metric 1 *Mar 17 22:57:53.654: RIP: received v1 update from 192.168.1.1 on FastEthernet0/0 *Mar 17 22:57:53.654: 192.168.10.0 in 1 hops Router2#no debug ip rip