[c-nsp] Same MAC addresses from two ports on different VLAN

Phil Mayers p.mayers at imperial.ac.uk
Sun Mar 14 08:51:47 EDT 2010


On 03/12/2010 07:21 PM, Jay Nakamura wrote:
> We have an Extreme Summit switch where I found that if you have two
> separate ports on different VLANs, and the same MAC address enters the
> switch on those two completely different VLANs, the switch will start
> having problems forwarding traffic.  (Or only use the first entry in
> the FDB, I am not sure what it actually does other than half of the
> traffic drops.)  Extreme support has confirmed that this is by design.

Which model? We've run several.

The only time I've ever seen this is when netlogin is enabled; you can't 
have a mac which is inserted into the FDB via netlogin on two ports.

It certainly doesn't happen with "ordinary" configs.


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