I currently have a client with over 50 site to site IPSEC VPN tunnels running GRE tunnels to enable them to use OSPF routing. I wish to build a tunnel from our ASA 5510 to most of these remote sites (most sites are using fairly old Cisco routers) The problem I have is that the ASA does not seem to support GRE tunnels so how can I get OSPF routing to work. I have a basic tunnel up and running but am not sure how to proceed if it is even possible. To change all the client tunnels to use tunnel protection thus bypassing the need for OSPF would not really be a viable solution as they would have to do a lot of network changes which I believe they would be unwilling to do.
Any ideas anyone?