I have one main office and two branch offices. The main office has 1 main router and 2 routers that are there to talk to the satelite offices. These two routers also connect to the main router. Each office is connected to the main office via a T1 connection. Each office has a CSU/DCU unit for the T1 line and a router. All routers are Cisco except the main one in the office. I am having trouble getting the branch offices to talk to the main office. I think the problem lies in the routing of the routers. I can ping both ethernet and serial links on of the router but only the serial link on another. Can someone explain what the correct routes should be from each office to the main office and what routes should be setup on the routers in the main office and the main router. Each router has ethernet0 and serial0 setup.