Showing results for 
Search instead for 
Did you mean: 

Error Disabled 2960-X Switch Trunk Ports due to Loopback


I am wondering if anyone could help me resolve the below issue I faced couple of days ago.


We had 10 2960-X switches which were working fine initially. And out of the sudden only 3 of these switches' trunk ports (Gi1/0/24) got error disabled due to loopback. The horizontal cabling was done with fiber optic cable so we use media converters at all ends.


Of course we have tried disabling *keepalive and setting *errdisabled recovery interval which helped with getting the switch port up but nothing more. The management VLAN interface's line protocol stays down.


We finally found out that there is some issue with one of the six media converters (3 pairs), and all worked after removing it. But I am not sure how this has come to be the solution since there is no way one faulty media converter could affect three links in the first place.


So, can any one help me understand deep how #keepalive works and what causes them from experience, please?

2 Replies 2

Leo Laohoo
Hall of Fame
Hall of Fame
What firmware is the stack running on?



 - Make sure to activate syslogging on all devices to a central syslog-server. This may give you better ways to analyze and scrutinize the problem when it occurs.


-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
    When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '
Review Cisco Networking for a $25 gift card