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Webcast-Catalyst9k
New Member

same mac addr.different vlan

I'm interested to know in the following sh mac-address table outputs, why i got four (4) same mac address in a different vlans of my network, Anybody got an explanation?

Thanks.

Leo

switch34.1#sh mac-address-table address 00d0.005e.4bfc

Mac Address Table

-------------------------------------------

Vlan Mac Address Type Ports

---- ----------- -------- -----

34 00d0.005e.4bfc DYNAMIC Fa0/24

33 00d0.005e.4bfc DYNAMIC Fa0/24

1 00d0.005e.4bfc DYNAMIC Fa0/24

5 00d0.005e.4bfc DYNAMIC Fa0/24

Total Mac Addresses for this criterion: 4

3 REPLIES
New Member

Re: same mac addr.different vlan

I've seen this before with MSFCs where the VLAN interfaces use the BIA address. As a result, all of the VLAN ip addresses resolve to the same MAC so you would see the same MAC address on multiple VLANs. Are you able to track down where the MAC address is being sourced from?

New Member

Re: same mac addr.different vlan

I would also check the arp table on your local router to see if the router has an entry or entries for that mac address if you are having problems tracking it via the mac or cam table.

New Member

Re: same mac addr.different vlan

Hi Leo,

the mac-address has to be unique in one segment, there is no need to use an other mac-address in different vlans.

Regards Frank

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