How can I extend my broadcast domains across a WAN?

[luke.paris]

I am planning a data center migration in which I'm installing a point to point DS3 between the two data centers.

I want to extend my VLANs (i.e. broadcast domains) over the DS3 to create a transparent LAN. This would allow servers at both data centers to reside on the same IP network so I can avoid making IP changes at the application layer.

How can I make the router that terminates the DS3 operate like a switch and treat the DS3 interface as though it were an ethernet LAN segment?

As a side note, I attempted to provision a Metro Ethernet service that would extend the VLANs providing a transparent LAN service, however, complications arose and now I'm in search of an alternative solution.

[smif101]

You would need to create a bridge network, however I wouldn't do that at all and just do it the right way. Change the IP on the servers once and be done with it because you will run into more problems than you want setting up and troubleshooting bridging.

[jboyer]

If it is a point-point DS3 it is easy. Enable IRB then create BVI interfaces on each side for bridging across the DS3. There are a couple of different ways to configure and I think the best in this scenario is to "ip unnumbered BVIx" on the serial interfaces - haven't tried this myself. The other option is to add "bridge-group x" to the ethernet ints but depending on other purposes for this router that might not be the best way.