Command Debug IP Routing Use This command enables debugging messages related to the routing table. This debug is particularly useful for finding routing loops. Since the routing table is normally stable, you will only see debug messges when there are route changes. Syntax Router#debug ip routing Example In …

Command Debug IP RIP Use This command enables RIP debugging messages. The debugging shows RIP updates that are being sent and received. Syntax Router#debug ip rip Example In the below example we enable RIP debugging on R2. R2#debug ip rip RIP protocol debugging is on R2# *Mar 1 …

Command Debug IP OSPF Adj Use Turns on OSPF adjacency events debugging on the router. Syntax Router#do debug ip ospf adj Example This example demonstrates what occurs when enabling adjacency debugging on R2. R2(config-router)#do debug ip ospf adj OSPF adjacency events debugging is on Shortly afterwards, int fa0/0 …

Command Debug IP Packet Detail Use This command enables detailed IP packet debugging messages. The debugging shows detailed IP information being processed by the route. , Also, you can use an access-list to limit the debug output. Syntax Router#debug ip packet detail  OR Router#debug ip packet detail <access-list> Example …

Command Debug IP OSPF Packet Use Displays the actual packets sent and received by OSPF. Syntax Router#debug ip ospf packet Example In this example, OSPF packet debugging is enabled on R2. R2(config-router)#do debug ip ospf packet OSPF packet debugging is on Here are some of the output after …

Command Debug IP EIGRP Use Shows all EIGRP routing messages. Syntax Router#debug ip eigrp Example In this example, debug ip eigrp is used to display all eigrp routing messages on R2. R2(config-router)#do debug ip eigrp Here are some of the debug messages shown after issuing the command. R2(config-router)# …

Command Debug IP Packet Use This command enables IP packet debugging messages. The debugging shows all IP information being processed by the router. You can also use an access-list to limit the debug output. Syntax Router#debug ip packet OR Router#debug ip packet <access-list> Example In the below example, …

Command Neighbor Use This command tells OSPF to communicate with unicast updates to a specific neighbor. This is particularly useful over non-broadcast links, such as frame-relay, as adjacenies will not form by default. Syntax Router(config-router)#neighbor <ip address> Example In this example, we will configure R4 to send its …

Command Auto-Cost Reference-Bandwidth Use Changes how OSPF calculates its metric. By default, a FastEthernet and above will have a cost of 1, so a gigabit interface will be equal with a fastethernet. This is not ideal. Syntax Router(config-router)#auto-cost reference-bandwidth <bandwidth> Example In this example, we will configure OSPF …

Command Passive-Interface Default Use This command prevents OSPF from forming adjacencies on all interfaces on the router. Using no passive interface default command is used to allow OSPF communication. Syntax Router(config-router)#passive-interface default Example In this example, we will use passive-interface default to block all OSPF adjacencies. Afterwards, we will allow communication through …