Index into mplsXCTable that identifies which cross- connect entry is associated with this route entry by containing the mplsXCIndex of that cross-connect entry. This field is only valid for a VPN BGP route where rtmRouteType is remote and rtmRouteProto is bgp. Where valid, a zero value for this field indicates that a label stack is not associated with this route entry. This can be the case because the label bindings have not yet been established, or because some change in the agent has removed them.