OSPF Failover Utilizing VPN and two T1's

bardellom · ‎10-28-2008

My question has to do with how to failover over between our primary WAN links (two T1's that terminate on the same router) and a VPN tunnel (on a different router) if only one of our T1's go down. The two T1's and the VPN tunnel are running OSPF and the T1's have the better administrator distance and cost. Currently if both T1's go down we failover to the VPN tunnel automatically.

owillins · ‎11-04-2008

This is possible if the bandwidth of the VPN tunnel is more than the bandwidth given by a single T1 link. As you are running OSPF it is possible to tweak the settings using which OSPF calculates cost of a link. Use the command "ospf auto-cost reference-bandwidth ref-bw" to set a lower bandwidth value than the default 108 and check if it works.

bardellom · ‎11-04-2008

Thanks, I'll give this a try.