In telecommunication, a switched multimegabit data services (SMDS) is a connectionless, broadband, packet-switched data service that provides LAN-like performance and features in metropolitan or wide areas.

Note: Currently SMDS operates at 1.544 Mb/s (megabits per second) or 44.736 Mb/s. These are the T1 and T3 rates, respectively, over switched fiber optic networks.

Source: from Federal Standard 1037C