Switched Multi-megabit Data Service
Template:Short description Template:Redirect Switched Multi-megabit Data Service (SMDS) 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 (CBDS).<ref name = "McDysan 1999"/>Template:Rp
SMDS was specified by Bellcore,<ref name="TR-TSV-000772"/><ref name="TR-TSV-000773"/><ref name="TR-TSV-000774"/> and was based on the IEEE 802.6 metropolitan area network (MAN) standard, as implemented by Bellcore, and used cell relay transport, Distributed Queue Dual Bus layer-2 switching arbitrator, and standard SONET<ref name="GR-253"/> or G.703 as access interfaces.
It is a switching service that provides data transmission in the range between 1.544 Mbit/s (T1 or DS1) to 45 Mbit/s (T3 or DS3). SMDS was developed by Bellcore as an interim service until Asynchronous Transfer Mode matured.<ref name = "McDysan 1999"/>Template:Rp 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.<ref name = "McDysan 1999"/>Template:Rp In the mid-1990s, SMDS was replaced, largely by Frame Relay.