Hello Sims
There are a couple of options for creating a frame relay topology.
If you have multiple sites, you can place all routers from all the sites on one subnet like so:
Notice that all serial interfaces are on the same subnet of 10.1.1.0/24. This topology does not require a separate subnet for each link, but one subnet for all routers. This requires the employment of a static frame relay map to map between a next hop protocol address and a DLCI destination address. This is done using the frame-relay map protocol protocol-address dlci [broadcast] command. Notice the broadcast keyword at the end of the command which indicates that this is a pseudo-broadcast implementation because frame-relay does not natively support broadcasts.
Concerning point to point links in frame relay, each link MUST have a separate subnet. This is the case in the following diagram:
In this case, one subinterface is created for each point to point link and each link between two subinterfaces has a separate subnet. The advantage of this is that routing protocols such as OSPF can function without the need for specialised commands such as removing split-horizon rules and such.
I hope this has been helpful!
Laz