Although the computer industry is still young compared to other industries
(e.g., automobiles and air transportation),
computers have made spectacular progress in a short time.
During the first two decades of their existence,
The merging of computers and communications has had a profound influence
on the way computer systems are organized. The once-dominant concept of the
‘‘computer center’’ as a room with a large computer to which users bring their
work for processing is now totally obsolete (although data centers holding thousands of Internet servers are becoming common). The old model of a single computer serving all of the organization’s computational needs has been replaced by
one in which a large number of separate but interconnected computers do the job.
These systems are called computer networks. The design and organization of
these networks are the subjects of this book.