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New Member

Nexus 5000 Mac Address Issue


I have an issue on switches mac address table.

I have started ping to a server connected to a Nexus 5000 from a host that also conected to Nexus 5000.

Ping results are always succeed.

However, when I check server's mac address on Nexus 5000 mac address table with "show mac address-table"; the mac-address of server RANDOMLY APPEARS AND DISAPPEARS on the mac address list. However, as I said before pinging is still succesfull, there is no problem in operation level.

I have check the cpu (%33) and mac address count (around 1000), everything looks like usual.

What can cause this issue?

Is that possible that "show mac address-table" does not shows up-to-date mac address table and there is a delay between "show mac address-table" and the mac address table that is used by switch?

Thanks in advance.

New Member

Nexus 5000 Mac Address Issue

Are you using vPC or even just regular Port-channel ??

in the running config you can add the command " mac address-table notification mac-move  "  then either turn on term mon and see if the mac is bouncing between 2 interfaces or port-channels. Or check the logs

Do you have 2 Nexus Switches and one acting as the peer switch??

Also is this server Vmware with multiple nics with a vswitch config ?? I have seen behavior with this, where vmware will have the nics teamed in a port group, But if the cisco switch is not setup as port channel the mac addresses can change from one interface to another.

Ned to know a little more about the switching and server environment to better answer your question

New Member

Nexus 5000 Mac Address Issue

Yes, we have two Nexus witch vpc confic and server is Vmware with mutiple nics.

Let me check if the problem occur again, when port-channel is used .

I will be back with the results.

**********By the way, thanks for "mac address-table notification mac-move" very usefulll command.********

Many Thanks,

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