Sometimes during troubleshooting, it may come in handy to be able to examine the packet...

Sometimes during troubleshooting, it may come in handy to be able to examine the packet coming into an interface on a Cisco router. This will be very handy when looking into buffer leaks and interface wedged issues.

Issue the following IOS EXEC commands:

Router# show buffers input-interface [interface type] [interface number] header command

Bookmark Share Link

Just enable it in the global configuration mode with 'jumbo', then restart the system.

Just enable it in the global configuration mode with 'jumbo', then restart the system.

Bookmark Share Link

%RTT-4-DuplicateEvent : RTR [dec]: Duplicate event received. Event number [dec]

Symptom:

%RTT-4-DuplicateEvent : RTR [dec]: Duplicate event received. Event number [dec]

Solution:

This informational error message indicates that the Cisco IOS device has received a duplicate round-trip time monitor - RTR - process event.

Issue the router# show rtr configuration Cisco IOS command to assess and troubleshoot possible conflicts.

 

 

 

Bookmark Share Link

The router will crash with a bus error

Bug ID:

CSCdr45483

Resolved In:

12.0(11)S1, 12.0(12)S, 12.0(11)SC1, 12.0(12)SC, 12.1(6), 12.1(6)AA, 12.1(6)T, 12.1(6)EC, 12.1(6)E1

Symptom:

The router will crash with a bus error

Conditions:

This crash occurred on a Cisco IOS router configured for multicast when the device was processing large amounts of unicast route updates. 

Workaround:

None

Solution:

This bug is fixed in 12.0(11)S1, 12.0(12)S, 12.0(11)SC1, 12.0(12)SC, 12.1(6), 12.1(6)AA, 12.1(6)T, 12.1(6)EC, 12.1(6)E1 and later releases of IOS.

Bookmark Share Link

1. To erase the configuration file, issue the erase nvram: command. Reload the ...

1. To erase the configuration file, issue the erase nvram: command.

Reload the router by issuing the reload command.

2. If this does not solve the problem, attempt to break into ROM Monitor (ROMmon) by issuing the break sequence (usually Ctrl and break from the Hyperterminal) from a console connection.



You should see this ROMmon prompt:

rommon 1>

3. Change the configure register value to ignore the startup configuration by issuing the confreg command, as shown in this example:

rommon 2> confreg 0x2142

4. To reload the router, issue the reset command, as shown in this example:

rommon 3> reset

5. After the router boots, issue the enable command at the Router > prompt. The prompt changes to Router#, indicating that the router is now in privileged mode.

6. To enter config mode, issue the config terminal command. You should now see a Router(config)# prompt.

7. To change the configure register to recognize the startup configuration, issue the config-register command, as shown in this example:

Router (config)# config-register 0x2102

To break out of configuration mode, press Cntl and Z.

To save the blank configuration, issue the copy-running config-startup config command.

Bookmark Share Link