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.