Cisco: Warning: SFP gbic-security check fail and gbic-invalid
Problem: I recently had to use some none Cisco 10Gbs copper SFP’s in a 3850 stack. On...
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Category: Cisco
Cisco IOS – Finding unused interfaces
Have you ever looked at a comms cabinet run of Cisco switches only to find that ever interface is...
Read MoreCisco Recovering a Cisco Router Using Rommon
The below details how to recover a Cisco router if you have forgotten the password of there is a problem with the configuration. WARNING: By doing this you may loose any configuration on the router. 1. You will need to be...
Read MoreOn a Ciscio IOS device when you view the logs or the debug logs the date and time is not displayed
If when you run show logging or try to view the debug logs on a Cisco IOS device the date and time is not displayed and instead you get something like the below, here is the solution. 6w4d: %ETHCNTR-3-LOOP_BACK_DETECTED:...
Read MoreClearing a Dynamic ARP Entry from a Cisco ARP Table
The ARP table on a Cisco device is a list of learned IP address and what MAC addresses they resolve to, this is required as generally switches work at layer 2 with MAC addresses not IP Address’s. Problem: If you replace a device...
Read MoreCisco Router Debugging Via Telnet
If like me you what to see the output of a dubug command via a telnet connection, follow the below steps 1) Enable Virtual Terminal Logging Telnet into the router and get yourself into privileged (Enable) mode and enter the...
Read MoreDeleting all the contents of a folder on a Cisco IOS device
Before you can remove a directory on a Cisco devices the directory must be empty, the below steps will show you how to delete all of the files and folders the directory contains. Most modern Catalyst switches store their IOS in...
Read MoreImaging a Cisco Router from ROMMON mode using TFTP
If you find yourself in ROMMON mode having done something silly like wiping the flash or if there was a problem updating the IOS then the below steps will go though how to copy a replacement image from TFTP to the routers flash....
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