Downindicates that the connection in at least one direction on a bidirectional link is degraded to the point of no longer passing traffic.
The East/West directionality for each topological link is determined during discovery.
The symptoms for DropSideTopologicalLink Down are as follows:
LOS on the PTP connected to the DropSideTopologicalLink
RFI on the PTP connected to the DropSideTopologicalLink
Signal Failure (SF) on the receiving PTP connected to the DropSideTopologicalLink