North American Network Operators Group

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Re: Peering VLANs and MAC addresses

  • From: Steven Bakker
  • Date: Wed Nov 09 14:57:24 2005

On Wed, 2005-11-09 at 10:39 +0000, Simon Brilus wrote:

> The peering exchange has an MoU that only 1 MAC address should be visible on 
> their switch.  However they see 2 MAC addresses on our port.
> - MAC address of Peering router
> - MAC address of the port they are connected to on switch A
> Is there any way to prevent switch A from presenting the interface MAC 
> address?  Or is this a symptom of spanning tree that cannot be stopped?

Has it been confirmed that the violating frames are in fact STP BPDUs?
Could be all kinds of other autoconfig crap (CDP, VTP, etc.).

Don't know your VLAN setup and I certainly don't know that much about
Cisco L2 features. Is it possible to have topology groups with a master
VLAN (the one that does STP) and member VLANs that don't speak STP? If
so, that may be a way to keep STP traffic from coming out of your IX
port (barring vendor bugs).

> Your input will be most welcome.

Is it absolutely necessary to run STP on the edge of the IX?

-- Steven