Can anyone please clarify the split horizon rules for Frame Relay. I have read conflicting descriptions from different sources.
As I understand it, for the main physical interface configured with encapsulation type Frame Relay, split horizon is disabled by default. This is unless EIGRP is being used in which case the command :-
no ip split-horizon eigrp
must be issued explicitly on the interface.
However what happens with sub-interfaces ? What is the default for split horizon for point-to-point subinterfaces, and for multipoint subinterfaces ?
Also, if split horizon is disabled, cannot routing loops then occur, as this is the reason for implementing split horizon in the first place ?