| 9.3 |  | Troubleshooting Router Issues Overview |
| 9.3.5 |  | Troubleshooting routing issues |

| The show ip protocols and show ip route commands display information about routing protocols and the routing table. The output from these commands can be used to verify the routing protocol configuration. The show ip route command is perhaps the single most important command for troubleshooting routing issues. This command displays the contents of the IP routing table. The output from the show ip route command shows the entries for all known networks and subnetworks, and how that information was learned. If there is a problem reaching a host in a particular network, then the output of the show ip route command can be used to verify that the router has a route to that network. If the output of the show ip route command does not show the expected learned routes or no learned routes, then the problem is possibly that routing information is not being exchanged. In this case, use the show ip protocols command on the router to check for a routing protocol configuration error. The show ip protocols command displays values about IP routing protocol information on the entire router. This command can be used to confirm which protocols are configured, which networks are being advertised, which interfaces are sending updates, and the sources of routing updates. The show ip protocols output also shows timers, filters, route summarization, route redistribution, and other parameters that are specific to each routing protocol that is enabled on the router. When multiple routing protocols are configured, the information about each protocol is listed in a separate section. The show ip protocols command output can be used to diagnose a multitude of routing issues, including identifying a router that is suspected of delivering bad router information. It may be used to confirm the expected protocols, advertised networks, and routing neighbors are present. As with any troubleshooting process, identifying the problem is difficult if not impossible if there is not documentation indicating the expected.
| Lab Activity Lab Exercise: Troubleshooting Routing Issues with show ip route and show ip protocols This lab uses the show ip route and show ip protocols commands to diagnose a routing configuration problem.
| Web Links show ip protocols Command http://www.cisco.com/en/US/products/sw/ iosswrel/ps1835/ products_command_reference_ chapter09186a00800ca759.html#1039245