Loop-Back_Detected

g_curuchaga · ‎11-27-2007

Hello, I have catalyst 2950 with IOS version 12.1(22).EA4, some times detects loop in the network, but we do not know the origin of the problem. How I can identify that it originates the problem?

regards

Guillermo

g_curuchaga · ‎11-27-2007

I send the log about the loop

Nov 27 09:57:29: %ETHCNTR-3-LOOP_BACK_DETECTED: Keepalive packet loop-back detected on GigabitEthernet0/1.

Nov 27 09:57:29: %PM-4-ERR_DISABLE: loopback error detected on Gi0/1, putting Gi0/1 in err-disable state

Nov 27 09:57:30: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to down

Nov 27 09:57:31: %LINK-3-UPDOWN: Interface GigabitEthernet0/1, changed state to down

Nov 27 10:02:29: %PM-4-ERR_RECOVER: Attempting to recover from loopback err-disable state on Gi0/1

Nov 27 10:02:34: %LINK-3-UPDOWN: Interface GigabitEthernet0/1, changed state to up

Nov 27 10:02:36: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up

Nov 27 10:03:01: %DTP-5-DOMAINMISMATCH: Unable to perform trunk negotiation on port Gi0/1 because of VTP domain mismatch.

Nov 27 10:13:21: %LINK-3-UPDOWN: Interface FastEthernet0/21, changed state to up

Nov 27 10:13:22: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/21, changed state to down

Nov 27 10:13:23: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/21, changed state to up

Nov 27 10:13:59: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to down

regards

Guillermo

jeanaguemon · ‎11-28-2007

It looks like there is VTP domain mismatch. Check the VTP domain name and password on the 2950 above and the switch connected to the G0/1. Monitor thereafter and let me know.

Jeanaguemon