Communications 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 network infrastructure.

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 broadband communications.

TECHNOLOGY INTERRELATIONSHIPS

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:

•  Users. They require cost-effective solutions to networking problems.

•  Technologies. The basis for network product development.

•  Standards. These are intended to stabilize the market and thereby make life easier and products cheaper for users and vendors.

•  Products and services. The goal is to increase revenue for the producer by solving users’ problems.

•  Vendors. They are trying to survive and thrive in a complex and dynamic environment.

•  Solutions. These use the technologies to create products and services.

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.

USER NEEDS

Users do not, in general, care about technology. Users simply want cost-effective solutions to their problems. The user’s ideal communications system is a single high-performance, economical network utility that accommodates all types of traffic and that provides the following:

•  Improved 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.

•  Better bandwidth use. Bandwidth costs are 70 to 80% of communications system life cycle costs. Effective use of expensive resources is important.

•  More reliability. Users recognize that resilience is an expensive quality if it is obtained with fully meshed networks; a solution is bandwidth on demand.

•  More flexibility. This means being able to reassign capacity to different applications and different types of information as the requirements change.

•  Economies of scale. Possible when one transport mechanism is used for all information types.

•  Data integrity. Error-ridden information is often worse than no information.

•  Management capability. Users need sophisticated management tools for operations, administration, and failure reporting and recovery.

•  Real-time 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.

Parallel Forces

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 distributed applications.

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.