6.4 Frame Relay Subinterfaces
6.4.3 The resolution of point-to-point and multipoint reachability issues
You can configure subinterfaces to support the following connection types:
  • Point-to-point -- A single subinterface is used to establish one PVC connection to another physical interface or subinterface on a remote router. In this case, the interfaces would be in the same subnet, and each interface would have a single DLCI. Each point-to-point connection is its own subnet. In this environment, broadcasts are not a problem because the routers are point-to-point and act like a leased line.
  • Multipoint -- A single subinterface is used to establish multiple PVC connections to multiple physical interfaces or subinterfaces on remote routers. In this case, all the participating interfaces would be in the same subnet, and each interface would have its own local DLCI. In this environment, because the subinterface is acting like a regular Frame Relay network, routing updates are subject to split horizon.