topic MAC flapping between cluster members in Firewall and Security Management

MAC flapping between cluster members

OlKuts — Thu, 23 Jun 2022 10:54:07 GMT

Hi,

We have cluster with 2 gateways and use VMAC for them.

These gateways connected to the switch and I noticed MAC flapping on it. On port 1 I see VMAC and physical MAC of active cluster member and on port 2 - physical MAC of standby member. In switch logs I see that physical MAC of standby member is flapping between these 2 ports. But cluster state wasn't changed, no related logs in /var/log/messages.

How this behavior can be explained?

Thanks.

Re: MAC flapping between cluster members

PhoneBoy — Wed, 29 Jun 2022 20:48:18 GMT

You'd have to look at tcpdump to see if the primary gateway is actually generating packets with the standby MAC.
To my knowledge, this shouldn't happen.

Re: MAC flapping between cluster members

OlKuts — Thu, 30 Jun 2022 09:49:07 GMT

Thanks for advise.

I collected tcpdump on active member and I see that for one VPN peer standby cluster member responses with his MAC with VIP IP.

Re: MAC flapping between cluster members

PhoneBoy — Fri, 01 Jul 2022 15:18:34 GMT

That could very well be a bug and probably needs a TAC case to investigate.