I have 1 central location with a 1721 router, and one remote location with another 1721 router joined by a T1. This has already been setup. These are configured strictly as a bridge. We have added a third remote location to join only the central location with another T1 and a 1721. I added another T1 DSU/CSU to the central located router. Again this needs to be setup as a bridge only. What do I have to add to the configuration of the central bridge for this configuration?