Chapter 13
Switched Multimegabit Data
Service (SMDS)
In this chapter, we present information about switched multimegabit data service (SMDS),
a data service that never achieved popularity in the United States. Our main purpose in dis-
cussing SMDS is twofold. First, the service is interesting in its own right and deserves
attention. Perhaps more important, though, is SMDS’s technical design and specifications.
SMDS is based on IEEE 802.6, a data link layer protocol for metropolitan area networks
(MANs). Called Distributed Queue Dual Bus (DQDB), this protocol is quite different
from other protocols we have considered and merits examination. An outline of the main
topics we address follows:
• SMDS Overview (Questions 1–2, 6)
• SMDS and Local and Interexchange ...