technology has become the core of the
distributed information system so vital to the
modern enterprise. Information, in the form of
data, voice, and, increasingly, graphics and
images, is transported among users by the vast
array of public and private communications
networks. These networks are evolving toward
much higher speeds and significantly lower
transit delays. Broadband networks, which is
what these high-speed networks are called, are
not being designed as an exercise to demonstrate
engineering capability. They are being developed
and deployed only because network service
providers see an increasing demand for
communications services that can only be met
with a low-latency, very fast, high-capacity
This chapter reviews the justification for this
perception. First the trends, forces, generic
applications, and user needs that are driving
the development of broadband communications are
examined, and the enabling technologies that
will provide the foundation for broadband
products and services are introduced. The
chapter concludes with an overview of the
broadband standards and architectures that are
prerequisites to the global availability of
Ultimately it will be the
broadband marketplace, whose structure is
illustrated in Exhibit 1, that will determine
the success or failure of broadband networking,
vendors, services, and products. This
marketplace is characterized by its diverse but
interrelated elements. It includes:
They require cost-effective solutions to
The basis for network product development.
These are intended to stabilize the market and
thereby make life easier and products cheaper
for users and vendors.
and services. The goal is to increase
revenue for the producer by solving users
They are trying to survive and thrive in a
complex and dynamic environment.
These use the technologies to create products
The market interrelationships
for broadband networking, at least initially,
seem ideal. The requirement to move increasingly
large amounts of information in ever-decreasing
periods of time is certainly real. At the same
time, the technologies that can be applied to
meeting this requirement are either here or just
over the horizon.
Users do not, in general, care
about technology. Users simply want
cost-effective solutions to their problems. The
users ideal communications system is a single
high-performance, economical network utility
that accommodates all types of traffic and that
provides the following:
performance. To be useful this must
translate into improved productivity. It takes
15 minutes to transfer a 1M-byte file at 9,600
bps but only 4 seconds at 2M bps.
bandwidth use. Bandwidth costs are 70 to
80% of communications system life cycle costs.
Effective use of expensive resources is
reliability. Users recognize that
resilience is an expensive quality if it is
obtained with fully meshed networks; a
solution is bandwidth on demand.
flexibility. This means being able to
reassign capacity to different applications
and different types of information as the
of scale. Possible when one transport
mechanism is used for all information types.
integrity. Error-ridden information is
often worse than no information.
capability. Users need sophisticated
management tools for operations,
administration, and failure reporting and
interaction. Information often has to be
timely to be useful.
These requirements are quite
general. They apply to any network, not just
high-speed networks. Users are often at a loss
to quantify these requirements, because it is
extremely difficult to predict the future in
other than very general terms. Users are
unanimous, however, in predicting that future
networks will have to move more information more
quickly and, of course, less expensively.
The industry is being driven
toward high-capacity, fast-response
communications networks by three parallel
forces. The first is a very rapid increase in
the number of small traffic streams, those
generating less than 64K bps, a result of the
expanding numbers of LANs and microcomputers.
There is also a huge installed base of
synchronous and asynchronous terminals and
devices generating traffic at rates of 600 bps
to 19.2K bps. Many small streams of information
begin to add up to large bandwidth needs.
A second force is the increase
in the number of graphic work stations, image
and video transfer, and networked mainframes,
all of which generate large streams of data. The
increase in both large data streams and
aggregated small streams is, in large part, the
result of distributed services being created by
A final but often overlooked
contributor is the desire to leverage
communications investment by integrating voice
traffic with the data traffic on the network.
Voice will remain, by far, the largest source of
information to be carried by broadband networks.