Earlier today we had several of these messages popping up and crashing one of our switches (3750) which I will call main switch for purposes of this post.
%SW_MATM-4-MACFLAP_NOTIF: Host XXXX.XXXX.XXXX on Vlan XXX is flapping between port g1/0/2 and g1/0/13
We had several sets of these messages for different pairs of ports.
The setup was a lab switch (HP) which and the servers connecting into it. This lab switch then connected into our main switch (3750) via 1 Ethernet cable.
We unplugged the lab switch that a server which had a load balancing plugged into it.
I read this post which states what the problem was or could have been. Which would be the fact that the same mac was coming up on two different ports causing the messages.
My question is, why would this affect our main switch? The flapping should only occur on the lab switch that the server is plugged into, not our main switch.
If the server was plugged into the main switch on two different ports I could understand the messages popping up on the main switch. However, since there was only one cable connecting the lab switch to our main switch I cannot understand why the flapping was occurring on the main switch.