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New Member

Different MAC-addresses on vlan on C6503 MSFC

I have a problem setting different mac-addresses on vlan interfaces in the MSFC. When i change the mac-adress on one vlan interface all vlan interfaces get the same mac. I have done this on some other 6509 with sup1 without any problems. This wouldn't been a problem in normal, but.....

I use one 6503 as BGP-router in a multihomed env.

One separate vlan to each upstream-provider with different /30 nets for the link. Between the catalyst and the provider I have a transparent filter/packetshaper with incoming and outgoing interfaces. On the filter I can group interfaces to belong to the same vlan, but when I group this interfaces the packetshaper stop forwarding because it doesn't know which interface to forward to because the mac-address is the same for different ip-addresses.

I know It's hard to explain this matter in text, but if anyone know anything about how to fix I would appreciate it.

Cisco Employee

Re: Different MAC-addresses on vlan on C6503 MSFC

From your description I assume you have a sup2/msfc2 system. This issue is documented in the release notes under MSFC restrictions:

"With a PFC2, if you enter the mac mac_address interface command, the configured MAC address is used for all VLAN interfaces. "

New Member

Re: Different MAC-addresses on vlan on C6503 MSFC

Thank you for the answer.

And yes it's a sup2/msfc2.

Do you think it's possible to do a workaround with HSRP on one vlan, whitout having a second router interface, to get the virtual mac-address of HSRP to assign to the vlan, and set update-source in BGP for that neighbor to the virtual ip-address of HSRP.


Re: Different MAC-addresses on vlan on C6503 MSFC

Nope--BGP won't work in this situation. You could source from a loopback on the same router, but I don't think BGP's going to allow you to source and terminate a TCP session on an HSRP address. You could try setting up an alias command, using a local ip address, with a difference MAC address, but I don't know that it's going to help you get your traffic shipped to a different IP address through BGP.


New Member

Re: Different MAC-addresses on vlan on C6503 MSFC


I think I'll buy another 6503 for the second upstream provider. (Less problem)

Thanks again for the help.

Case closed


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