Tuesday, January 24, 2012

Cisco Configuration Tip - Protect Your Tail

cisco command reload
I have long been a fan of the Cisco "reload in/at" commands. These have saved my tail a number of times. This enables a brave network engineer to schedule a device reload for either a specific amount of time from now, 15 minutes, or just a specific time such as 11:00pm.

Protect Your Tail
Network Engineer Protecting His Tail
This has saved my tail a few times when working on a remote device. When changing ACLs or firewall rules there is always the potential of getting locked out. It has also saved me when debug messages flooded a device and I could not get the telnet/ssh session to respond.

Bonus Tip: When I have to debug a router or a switch I open a second telnet/ssh window. The primary window is set to terminal monitor so I can see the messages. In the second window I type in "undebug all" but don't press enter. If the debug messages get out of hand in the primary window, I switch to the second window and hit enter.
 Before making configuration changes, do the following:
copy run start
terminal monitor (so you can see reload countdown warnings
reload in 15

You are now free to make changes. If you get locked out, sit back and wait for the reload.

When you have made changes and still have access type:
reload cancel
copy run start