Operationally disabled is the normal operational state for STP on a spoke SDP in a VPLS that has any of the following conditions:
VPLS state administratively down
Spoke SDP state administratively down
Spoke SDP state operationally down
If the spoke SDP enters the operationally up state with the STP administratively up and the spoke SDP STP state is up, the spoke-SDP transitions to the STP spoke SDP discarding state.
When, during normal operation, the router detects a downstream loop behind a spoke SDP, BPDUs can be received at a very high rate. To recover from this situation, STP transitions the spoke SDP to a disabled state for the configured forward-delay duration.