Switch MAC Address Assignment

Unanswered Question
May 15th, 2007


Please let us know where we could find the Switch Base MAC Address?

Further, We have experienced that on a Catalyst 4506 we have same MAC Address for all the VLAN interfaces created.

So how does the ARP lookup happen as L2 address for all the VLAN is same?

On a Catalyst 3750, it has been noticed that we have different MAC addresses for each VLAN interface. In this case how many MAC Addresses are reserved by the Switch?

Does the Switch also reserves MAC Address for Port-Channel Interfaces?

To summarize how are the MAC Addresses assigned on various Catalyst Switches.

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
ankbhasi Tue, 05/15/2007 - 23:11

Hi Tej,

To get the base mac address command issue a command "sh version"

On most of the cat switches you will see same mac address on all vlan interfaces. Cisco switches support per-vlan mac-address table or CAM table. This allows the switches to maintain mac-address table per vlan, hence having the same mac-address on multiple-vlan interfaces is not an issue.

The 2970 and 3750 series switches have a unique mac-addresses for each SVI. SO the number of SVI you will create you will be assigned a new mac address.

To summarize is most of the cat switches per-vlan mac-address table or CAM table is supported.



tejpreet1111 Wed, 05/16/2007 - 00:41

Hello Ankur

Thanks 4 the reply.

By issuing the command "sh version:" we get the MAC address on 3750 but not on 4506.

I have tested on both till now.

Also, what is the limit to the number of VLAN L2 Addresses would be 1024 per switch in which we have unique mac-address per SVI.

Could you also through some light on the MAC Address for Port-channel.

What is the limit for the number of MAC Addresses reserved on 2970 / 3750.




This Discussion