This gauge reports the aggregate port identifier that the neighboring device associates with the far end of this Fibre Channel link, as discovered by the physical Fibre Channel endpoint representing one FC-facing port on the fabric interconnect, together with the neighbor device it discovers on the wire. An administrator verifying that a port channel is correctly bundled on both ends compares peerAggrPortId on this PhysFcEp instance against the local aggrPortId to confirm the two sides agree. For example, a mismatch between aggrPortId and peerAggrPortId on this PhysFcEp instance would explain why a port channel is not forming correctly with the neighboring switch.