IPSEC VPN w/ ISDN Internet backup

[bdedek]

Hi,

I am looking for documentation or a config on how to implement IPSEC encrypted ISDN dialup internet access, as a backup to a dedicated T1 IPSEC VPN. Basically I have 1760 with a T1 internet connection running a typical IPSEC VPN back to a central hub, using GRE and routing protocols to detect failures. I have currently implemented ISDN DDR back to the main hub, but would like to eliminate long distance charges on my ISDN line. I can have a dialup ISDN account with the ISP for backup, but I am not sure how to setup the router to have a failover IPSEC VPN on the ISDN internet connection when the T1 goes down. Any one have a similar scenario? I have successfully made the IPSEC VPN work over the ISDN dialup, but I'm not sure on how to set it up as a failover secondary connection.

Thanks,

Billy Dedek, CNE, CCNA

[drolemc]

Please see the document at http://www.cisco.com/warp/public/707/ipsec_dialerwatch.html. Though it does not use GRE, it deals specifically with building IPSec redundancy over an ISDN interface. You could also find a number of documents on GRE on the IPSec support page http://www.cisco.com/pcgi-bin/Support/browse/psp_view.pl?p=Internetworking:IPSec&viewall=true.