GLBP disabled automatically

[laukiknahar91]

The glbp got disabled on both groups and couldnt find the reason for this.

Logs from the router -

018895: Aug 9 01:11:15.731 mumbai: %GLBP-6-FWDSTATECHANGE: GigabitEthernet0/0 Grp 10 Fwd 2 state Active -> Disabled
018896: Aug 9 01:11:15.731 mumbai: %GLBP-6-FWDSTATECHANGE: GigabitEthernet0/1 Grp 20 Fwd 2 state Active -> Disabled

Also , we got no logs on the syslog server about the port went down or anything which can explain why it went to disabled state.

Tried searching but found -

%GLBP-6-FWDSTATECHANGE: FastEthernet0/0 Grp 1 Fwd 1 state Active -> Disabled   <----AVF's virtual mac is disabled

What is the exact reason behind this , need help ?

Attached is the show tech-support output.

[Mark Malone]

Hi

did you check the stp of the connected switches see if they caused it , is there anything in there logs , if something happened on switch side at layer 2

if the AVF is not known GLBP wont work and will disable , so what happened that mac is what you need to find out

Use this see if it shows any of the connected ports to the routers as something that was in a calculation recently on LAN side may have caused it

sh spanning-tree de | i ieee|occur|from|i exec

Disabled: Indicates that the virtual IP address has not been configured or learned yet, but other GLBP configuration exists.

Disabled: Indicates that the virtual MAC address has not been assigned or learned. This is a transitory state because a virtual forwarder changing to a disabled state is deleted.

[laukiknahar91]

Hi Mark

The network was up and running on this configuration, but suddenly got this message alert(GLBP disabled).

Right now the network is fine but need to get to the cause why this alert was shown.

The only change made was IOS upgrade of the router. Is it the reason why this happened as the IOS on both router were different ?

Also checked the connectivity ,after IOS upgrade on the router , but found nothing. Everything was working fine , even the GLBP was working fine.

This GLBP disable issue was faced few hours later the IOS upgrade.

[Mark Malone]

Hi
you need to run that full stp command it breaks down the details and shows exactly where and when the last changes were seen from like below extract from my switch , I cant see what your connected to on the routers if there was an stp change as cdp is disabled on the ports on the router

STP check is important as an inline  LAN TCN could cause a topology change at layer 2 and cause a recalculation put the ports in a spin which could shut down an FHRP temporarily until it resets , as layer 2 ports even switch side will be part of calculation if its an STP issue, this could be caused by a failed port you may not have to do anything to kick it off

Number of topology changes 17 last change occurred 2w5d ago
          from Port-channel122

The only change made was IOS upgrade of the router. Is it the reason why this happened as the IOS on both router were different ?

Should not be the issue unless theres a registered bug for GLBP on the release notes of either IOS version have you checked them what caveats are open , the release notes are available where you downloaded the IOS on Cisco website , you can have GLBP mixed across different platforms and versions usually without issues once its supported

You may not get the root cause of this, most issues like this have to be captured in real time with debugging outputs and wiresharks all you have is an alert notification and unfortunately the issue is not occurring anymore , there could have been a software glitch on one side that even rectified itself a once off they do happen