This is the peer-address-keyed counterpart to cpwVcIdMappingVcIndex, letting a management station look up which row in cpwVcTable corresponds to a pseudowire toward a specific peer, rather than by VC ID. An engineer who knows only the remote PE router's address can use this mapping to find the local VC entry serving that peer without already knowing its internal index. This matters on routers terminating many pseudowires to the same peer, where VC ID alone wouldn't disambiguate which specific circuit is affected.