Dear all,i found there is mac flapping between two port and the mac address is 0080c8000000

[SZU CHI CHEN]

it's very strange

i can't found it in other switch except cisco 3550 forwarding table

any expert know what is it ? <0080c8000000>

thank you

Host 0080.c800.0000 in vlan 12 is flapping between port Gi0/4 and port Gi0/11

[Leo Laohoo]

Try this link:

http://www.coffer.com/mac_find/?string=0080.c800.0000

[SZU CHI CHEN]

0080c8000000 is unusual mac address

how can i locate and identify it

[Leo Laohoo]

how can i locate and identify it

But you already have the answer right in front of you.

Host 0080.c800.0000 in vlan 12 is flapping between port Gi0/4 and port Gi0/11

The answer you seek is plugged into ports Gi0/4 and Gi0/11.

[bgandhi]

Hi,

This is more to do with host than the switch issue. The switch would report MAC address flapping issue when it laerns same MAC address from 2 differenet interafces. If you enable port-security this port would go into error disable state.

Sugegst you check the host configuration, it may happen if teaming is wrongly configured. The guidelines for teaming configuration are mentioned in the link below.

http://www.cisco.com/en/US/partner/products/hw/switches/ps700/products_tech_note09186a00800a7af0.shtml#nic_teaming

The MAC address is registered with 0080C8     D-Link     (also Solectek Pocket Adapters, and LinkSys PCMCIA). Sugegst you get the unwanted features disabled on the host. e.g 802.1x authentication.

Hope this would help you.

Regards,

Bhavesh

[Ganesh Hariharan]

it's very strange
i can't found it in other switch except cisco 3550 forwarding table
any expert know what is it ? <0080c8000000>
thank you
Host 0080.c800.0000 in vlan 12 is flapping between port Gi0/4 and port Gi0/11

Hi jason,

The following mac 0080c8 belongs to D-Link (also Solectek Pocket Adapters), Just check out the two port for any teaming configuration or load balacning configuration behind these ports for any specfic devices or server.

Hope to Help !!

Ganesh.H

[Prabhdeep Nijjar]

Hi Jason

As already discussed in this issue, the MAC 0080.c800.0000 belongs to Vendor:D-link. The simplest way to find from where this MAC is coming, is following:

1. Check what is the configuration of both these ports

   A. If they are both access port, then these hosts must be connect to the same D-Link device.Remove that D-link device and           connect the PCs directly and the problem will be resolved.

   B. If one port is an Access and the other a Trunk , then follow the MAC address across the Trunk , till you narrow it down to a              host connection.Then check how the host is related or connected to the Access port on 3550.

2. And you have mentioned that you are seeing the MAC only on 3550 , which means that the loop is on this switch only. Check            the interface physically and remove the redundant link.

In a nut shell , all it means that this problem happens only when there is a LOOP in the network.

Hope it helps,

Prabhdeeep Nijjar

[lescarfullery]

I had a similar problem and no loops in my network. I found a common factor, the MAC shown in the error were from Hosts with IPv6 enabled (windows 7). I disabled IPv6 on all my network hosts and the MAC flapping error stopped. I asked Cisco support about it and they never heard about that issue.