Frame Relay allows you to interconnect your remote sites in a variety of topologies such as the following:
Star topology: Remote sites are connected to a central site that generally provides a service or an application. The star topology, also known as a hub-and-spoke configuration, is the most popular Frame Relay network topology. This is the least expensive topology because it requires the least number of PVCs. In the figure, the central router provides a multipoint connection because it typically uses a single interface to interconnect multiple PVCs.
Full mesh topology: All routers have VCs to all other destinations. Full mesh topology, although costly, provides direct connections from each site to all other sites and allows for redundancy. When one link goes down, a router can reroute traffic through another site. As the number of nodes in this topology increases, a full mesh topology can become very expensive. Use the n(n–1)/2 formula to calculate the total number of links that are required to implement a full mesh topology, where n is the number of nodes. For example, to fully mesh a network of 10 nodes, 45 links are required: 10(10–1)/2.
Partial mesh topology: Not all sites have direct access to all other sites. Depending on the traffic patterns in your network, you may want to have additional PVCs connect to remote sites that have large data traffic requirements.