[c-nsp] Bridging solution for 5 locations

[Jeff Crowe]

Hi all,

I am trying to establish a bridged solution for 5 locations that are served
via ADSL non-authenticated connections.  These ADSL connections are
delivered to us via a wholesale provider and we do not have the ability to
control the network or implement changes.

The network topology of the locations is a flat 192.168.0.x/24 with the
address space spread across each of the 5 locations.

Each separate ADSL connection is delivered to me via separate VLAN's over an
Ethernet trunk.  I have put that trunk into a Cisco 2651 and created a
bridge using IRB.  Data flows for a short while, but then packets stop
flowing between locations.  After some troubleshooting and guessing - I
think the problem is with MAC address flapping on the wholesale provider
network.  Either they have spanning tree enabled or mac-address learning
enabled on their core and this is causing my bridged connections to cause
grief on their network equipment and shut down the paths.

My question is:  What would be a simple solution to allow these 5 locations
to communicate between each other without changing the network topology?  I
looked into GRE tunnels, but they will not allow a broadcast network to span
multiple locations.  

Should I be looking into L2TPv3 type tunnels and put a CPE at each location
to control the tunnels?  If so - what is the lowest form of router that
could be used? (Cisco 17xx?).

Is it possible to do MAC NAT'ing on a Cisco device?  This would allow me to
keep the mac addresses separated on each vlan and still allow for bridging.

Thanks,

Jeff.