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