Anyone who has fiddled with IP VPN or Cisco MPLS knows it’s a bizarre beast. No PVCs, the network’s magically fully-meshed, and you need special routers.

So how do you back up an IP VPN connection? Traditionally, if you got a, say, a frame relay T1, most places settle for an ADSL, ISDN dial-on-demand, a 56K dialup line, a fractional T1 or even a second T1, depending on how much bandwidth and functionality you needed in a backup situation. But these things won’t work out in VPNe La-La Land.

It’s simple: to back up an IP VPN connection, you use a second IP VPN connection. If you have an IP VPN T1, for instance, you can run a second VPN T1 or go for a cheaper IP VPN ADSL link. Keep in mind the ADSL link will have a lower MTTR, and will be less reliable.

Depending on your service provider, you will probably have three kinds of diversity. For the cheapest way, just have both your primary and auxiliary connection go to the same provider edge router. For a bit more added protection, you can have the two connections go to two separate PE routers. If you’re the belt-and-suspenders type of person, you can go all out and have these two connections go to two separate PE routers housed in to separate COs.