When tmnxOamP2mpLspTrMapAddrType has a value of 'ipv4Address'
tmnxOamP2mpLspTrMapDSIfAddr indicates the downstream LSR's
interface address. When tmnxOamP2mpLspTrMapAddrType has a value
of 'unnumbered', tmnxOamP2mpLspTrMapDSIfAddr indicates the index
assigned by the upstream LSR to the interface.