Actually one of our customer is shifting from ISDN to LEASED LINE and the problem is the service provider here provides different ip addresse range for each type of service.But for our customer it is vert difficult to tell all of his users that from now to own you should some other IP for the VPN, so to make this change seemless to the end users or to make this change slowly ,wt can we do,
One thing that comes in our mind is to assign two ip address to outside interface so that same interface will terminate the VPN Tunnel orignating for two different IP address.
OR if any body have any other solution then pleasle let me know, i'll be very thank full to u.
sameer