[AusNOG] The occurrence of duplicate MAC addresses

[Gavin Tweedie]

On 8/02/2013 2:51 AM, Paul Brooks wrote:
> ...remembering that duplicate MAC addresses aren't actually a problem
> unless you get two of them on the same broadcast-domain LAN. Within  an
> 'IP Core' there usually aren't many high-node-count broadcast domains.
> Many many point-to-point real or virtual links with 2 addresses, many
> VLANs with less than 20 nodes perhaps.

Not a lot of large broadcast domains within a SP routed network, but 
they do occur at the edge of SP networks at exchange points, and in 
layer2 backhaul (ethernet DSLAM backhaul, NBN..).

Bad luck for guy #2 who rocks up to the peering point with the same MAC 
as an existing member eh? Or potentially bad luck for both if nobody 
notices before they connect.

An interesting stat to know would be what sort of vendor equipment this 
is occurring on, is it just low end home gateway devices or does the 
vendor have the same issue on higher end gear?

Gav