Switched Multi-megabit Data Service
Switched Multi-megabit Data Service was a connectionless service used to connect LANs, MANs and WANs to exchange data, in early 1990s. In Europe, the service was known as Connectionless Broadband Data Service .
SMDS was specified by Bellcore, and was based on the IEEE 802.6 metropolitan area network standard, as implemented by Bellcore, and used cell relay transport, Distributed Queue Dual Bus layer-2 switching arbitrator, and standard SONET or G.703 as access interfaces.
It is a switching service that provides data transmission in the range between 1.544 Mbit/s to 45 Mbit/s. SMDS was developed by Bellcore as an interim service until Asynchronous Transfer Mode matured. SMDS was notable for its initial introduction of the 53-byte cell and cell switching approaches, as well as the method of inserting 53-byte cells onto G.703 and SONET. In the mid-1990s, SMDS was replaced, largely by Frame Relay.
