This value selects the physical/link media type for the local interface this route to the destination network is reached through from a large fixed enumeration (Ethernet, TR4/TR16, FDDI, a range of synchronous/async HDLC and X.25 speeds, fractional/full T1 rates, or a VINES-over-IP tunnel), defaulting to Ethernet where applicable. The enumerated values cover every WAN/LAN media type the Wellfleet router's VINES stack could run over at the time -- Ethernet, 4/16 Mbps Token Ring, FDDI, various synchronous/asynchronous HDLC and X.25 speeds, a range of fractional/full T1 rates, and a VINES-over-IP tunnel. An admin sets or reads this to confirm the VINES stack has the correct media type recorded for this circuit, which matters because VINES uses per-media-type default costs and framing assumptions.