RE: Layer2 troubleshooting

Can you identify what is host with MAC 0022.196b.cd00 and where it connects
?

In the meantime my glass ball is telling me that you have a Dell server on
the network that has two or more NICs configured in "teaming". The server
achieves load balancing by swapping the same MAC address between NICs.
Switches see that as MAC flapping. If the server connects to different
switches, than the same MAC will be seen from different directions, like in
this example via a trunk on Gi0/1.

Does the server connect to int Fe0/8? Is it a VMware server running DOT1Q on
its hardware or virtual switch ?

If my glass ball is right then there is nothing to worry about. The error
that you are seeing is only a notification not an error. If it is not right
then a diagram and more detail will help.

Also, unless this is a very old problem, I suggest that you adjust ntp
settings on your switches :)

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
Jeferson Guardia
Sent: 14-May-10 18:40
To: groupstudy
Subject: Layer2 troubleshooting

 GS,

I am experiencing something weird on a switching scenario. Basically 2
layer2 switches
connected through a patch panel.

I started getting the following message and errors started to increment

 *Sep 14 08:54:05.896 BR-EST: %SW_MATM-4-MACFLAP_NOTIF: Host 0022.196b.cd00
in vlan 2006 is flapping between port Fa0/8 and port Gi0/1

In order to troubleshoot it, I put one side on shutdown while I would check
the configs and look
for problems. But while one side is administratively shutdown, on the other
side I still see it
up/up. weird?! The physical connection has been checked.

My configs on both sides:

SW A

interface ethernet 1/52
 description UPLINK AAE01 - P.8
 shutdown
 switchport allowed vlan add 1 untagged
 switchport ingress-filtering
 switchport native vlan 1
 switchport allowed vlan add 2006 tagged

SW B

Current configuration : 126 bytes
!
interface FastEthernet0/8
 description PRORESERVE - DKA 7o.
 switchport trunk allowed vlan 2006
 switchport mode trunk
end

Any thoughts?

Rgs,

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Received on Sat May 15 2010 - 00:20:36 ART