Backup link for L2L IPSEC Tunnel

[steve.wadge]

Is it possible to configure ISDN backup for an IPSEC L2L tunnel between 2 routers.

IPSEC L2L connection from remote site to HO. Need to provide a backup solution for if the remote sites ADSL connection goes down. Cannot do normal DDR as cannot run dynamic routing protocol over IPSEC tunnel?

Need to somehow monitor IPSEC tunnel to see if goes down & then initiate an ISDN call.

IPSEC configured for pre-share, des, md5

[vcjones]

Yes it is possible and I have several clients with ISDN backup of IPSec in production applications. The "trick" is that you do need to run a routing protocol to detect tunnel failure.

There are several ways you can run a routing protocol over the IPSec tunnel. I prefer to use BGP rather than OSPF or EIGRP, which eliminates the need to set up a GRE tunnel for the routing exchanges. See the "Redundant Routes in IPSec VPNs" white paper on my web site for a discussion and sample configurations.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com