On partially meshed Frame Relay networks, the problem of split horizon can be overcome by using Frame Relay subinterfaces. Frame Relay provides a
mechanism to allow a physical interface to be partitioned into multiple virtual interfaces. In a similar way, using subinterfaces allows a partially meshed network to be divided into a number of smaller, fully meshed point-to-point networks. Generally, each point-to-point subnetwork is assigned a unique network address.
This allows packets received on one physical interface to be sent out from the same physical interface, albeit forwarded on VCs in different subinterfaces.

There are two types of subinterfaces supported by Cisco routers: point-to-point and multipoint subinterfaces.