2

Due to our clunky monitoring, we are watching an IP on a bridge interface on a Cisco C800, which sometimes won't have any active FastEthernet connections which means the bridge goes into the down state.

This then raises alarms which are pointless.

Is there some way of forcing the bridge (BVI) to stay up, even when all the interfaces are down? I think that using the timeout option may work, but I'm unsure if it'll work on a bridge interface?

  • I think you can exclude it from the log by using no logging event link-status – user36472 Nov 14 '17 at 13:43
  • We aren't pulling the log for our monitoring, it uses snmp. While we could just 'ignore' the interface, that leaves us with no monitoring on the lan side. – djsmiley2k - CoW Nov 14 '17 at 19:48
  • sometimes won't have any active FastEthernet connections... means your neighbor devices at both ends go offline at the same time? – Hung Tran Nov 18 '17 at 0:46
  • @HungTran it's a edge device - connected to some laptops... sometimes. – djsmiley2k - CoW Nov 19 '17 at 15:34
  • @djsmiley2k I have added my answer. Please try it out. – Hung Tran Nov 19 '17 at 16:01
3

I'm not sure if it's supported on the C800, but try no autostate under the VLAN interface.

This will hold the VLAN up on most devices even when all member ports are down.

  • I've not been able to test, but I've also found the same instructions for this. We've now actually changed the configs so they no longer use the BVI's anyway so it's no longer a problem :) – djsmiley2k - CoW Mar 29 '18 at 7:59
1

If you have any spare switches, the trick is to place them between your C800 router and end devices (here are laptops as you commented).

BVI bridge interface will go down when all of the bridge ports are down. Therefore, If you can keep one of those ports up (by connecting it to a switch, and of course this switch must stay up together with C800 router), BVI will remain up.

Updated answer:

You can try to disable keepalive to see if it works for you for not.

  • Thanks for that idea but it's really not what I'm looking for. – djsmiley2k - CoW Nov 20 '17 at 14:25
  • 1
    @djsmiley2k Okay. If you stick to your idea Is there some way of forcing the bridge (BVI) to stay up, even when all the interfaces are down?, I think it is not possible. You might think about keeping one of bridge ports/interfaces always up (no matter what), then the problem would be resolved. You can try to disable keepalive to see if it works for you. – Hung Tran Nov 20 '17 at 16:19
  • @djsmiley2k Have you had a chance to test it out? – Hung Tran Nov 23 '17 at 8:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.