Switched Multi-megabit Data Service

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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).[1]:510

SMDS was specified by Bellcore,[2][3][4] 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[5] 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.[1]:510 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.[1]:214 In the mid-1990s, SMDS was replaced, largely by Frame Relay.


  1. ^ a b c McDysan, David E.; Darren L. Spohn (1999). ATM Theory and Applications. Montreal: McGraw-Hill. ISBN 0-07-045346-2.
  2. ^ TR-TSV-000772 Generic System Requirements in Support of Switched Multi-Megabit Data Service, Telcordia.
  3. ^ TR-TSV-000773 Local Access System Generic Requirements, Objectives, and Interfaces in Support of Switched Multi-Megabit Data Service, Telcordia.
  4. ^ TR-TSV-000774 Switched Multi-Megabit Data Service (SMDS) Operations Technology Network Element Generic Requirements, Telcordia.
  5. ^ GR-253 SONET Transport Systems: Common Generic Criteria, Telcordia.

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