[c-nsp] Backup IPSEC with ISDN

[Jonathan Soler (EU)]

Hi,

I have a customer that has some remote sites with ADSL connectivity that
are connected to a remote LAN with IPSEC.
The remote LAN has to entry points so the remote routers has a crypto
map with to peers in the same crypto map.

I am going to install a backup to this VPN network by installing a
central router with ISDN interfaces for doing an ISDN backup.

I am thinking in this backup solution and I do not know how to do it??
The customer needs this:

When the first tunnel fails to the first peer, the tunnel will establish
with the second peer (this is now configured), and now we need to add
that when the second tunnel fails (the IPSEC connectivity fails, not the
ADSL interface goes down) the router must make a call to the backup.

How can I do it?

Thanks,
Jonathan