Issue with mac address flapping

[carl_townshend]

Hi All

We have a funny issue whereby we are seeing mac address flaps coming from 2 port channels.

The mac address in question is the mac address of the core switch L3 interface.

The connectivity is core 4500 - 3750x - hp blade switch, we are seeing the messages on the 3750x and the mac address is seen on the connection to the core and from the hp blade switch.

we have shut all individual ports down and still get the same issue, configs and patching is all ok.

bug or issue on the 3750x maybe?

[paul driver]

Hello
You dont say how the blade server is connected to the 3750? -  Meaning does it have multiple PC interconnected or a sinlge PC.

Are you using any link-aggregation (LACP) , Doyou have any L2 link protection such as UDLD, loopguard, STP root guard appended to the 3750 downstrean towards the Blade sever?
What stp mode are you running?
Do you have any span sessions running?

[carl_townshend]

Hi Paul

Downstream switch has LACP configured

UDLD is not configured on this switch.

Both switches are running RTSP

No span sessions running.

I believe they said there was a power issue sometime last week, maybe the switch did not come up cleanly?

[paul driver]

Hello

So you do you have multple PCs?
Suggest you enable UDLD, and also possibley rootguard.

Are you aware of any flapping links that could be causing multiple stp retransisions?

sh interface | in line|\/sec
sh spanning-tree detail | in occu|from|is exec
sh spanning-tree int x/x detail | in BPDU

[carl_townshend]

Hi

We will give the switch a reboot first, nothing has changed, we will see if this helps.

What do you mean by multiple pc's ?

cheers

[paul driver]

How many Port Channels do you have between the blade server and 3750 switch?