Question about Frame Relay

xwesleyxwillisx

Tomorrow I'm going to be taking the ICND to hopefully complete my CCNA. I have heard that Frame Relay is the stressed WAN protocol over ISDN. I know how to configure both but I have a question. When you set up your routers for Frame Relay, is it common practice to set up subinterfaces in only a two router scenario? I realize that each subinterface is for each individual PVC, so I would think they are unnecessary when only 1 PVC is established between 2 routers. I also understand that Frame Relay is meant for connecting multiple sites, and therefore multiple routers. So the mere 2 router scenario seems unlikey. However, I do want to be prepared in case it comes up on the exam or even a future endeavour.

Thanks beforehand.

tunerX

PPP is usually stressed over ISDN due to the MLP and fragmentation capabilities.

There are three main topologies.

Full-mesh
partial-mesh
Hub and spoke

Usually you will only the physical interface in a hub and spoke topology, or a single circuit. With frame relay you should configure sub interfaces because it allows for additions and deletions of dlci's without having to mess with the physical layer.