I work at a company that has 2 offices separated by approximately 5 miles. Each facility has it's own dedicated T1 access to our ISP. Our offices are connected privately through 2 T1's (multilinked). I am wondering if it is possible to create some type of failover so that if one sides internet T1 dies the traffic would route across the internal T1's and out the other locations Internet connection. There are also 2 dmz's created, one at each site, with servers providing external services to our sales reps and customers. If I try and create some type of fault tolerance would I be able to keep both DMZ's up and running? I'm not looking for detailed examples or time consuming responses as I know this isn't really the place. I feel confident I can pull it off it it's possible and some one can point me in the right direction.