This read-only PnniPortId is a 4-byte logical port identifier of the traversed node in the trace, where a value of 0 indicates the destination node for the trace has been reached. An administrator reads this to know which egress port the traced call used at each hop, and to detect trace completion when the value hits 0. For example, an engineer stops walking further trace entries once cwspConnTraceEgressPortId reports 0, since that marks arrival at the call's destination node.