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T1 Survival--Not Just for the Fittest Anymore

September 14, 2001

Sebastopol, CA--At first glance, T1 appears to be an awkward technology with all the flash and excitement of indoor plumbing. The second glance is not much better: T1, the current network standard for business and professional Internet access is neither efficient, easy to use, nor particularly well suited to data transmission. Yet, like indoor plumbing, it's pretty pervasive and hard to imagine doing without.

That's where the similarity ends. Plumbing is relatively easy to understand, but T1 technology, while widespread, poses many challenges to the network administrator who must deal with it on a regular basis. As Matthew Gast, author of T1: A Survival Guide (O'Reilly US $29.95) explains, "Most network administrators have learned to use T1 by a retrograde system of unofficial apprenticeship and by painstakingly assembling numerous disjointed nuggets of information into a mostly-coherent whole. It is not a process that inspires an understanding of the big picture or the practical details."

According to Gast, T1 is a technology that was originally developed by AT&T to increase the capacity of the national telephone network in the 1960s. In the 1980s and 1990s, however, it began to be used to transmit data. Now, nearly all new T1 installations are used for data networking, and many of those are for the purpose of providing Internet connectivity. "Problems with the T-carrier hierarchy stem from one simple fact: T-carrier systems were designed for AT&T's voice network," explains Gast. "They can be used to transport data, but the adaptation to this use is not always a clean one."

In today's world, T1 lines are the standard for dedicated business Internet connectivity. They function as the veins and arteries that carry Internet traffic to its destination. In spite of its limitations, T1 is a proven, reliable technology that currently meets the need for medium-speed, high reliability Internet access by institutions of many sizes, and it's likely to be around for a while. T1: A Survival Guide supplies the practical information that network administrators need to understand how to work with this central technology.

"The way our industry has taught network administrators to use T1 has been medieval at best," says Gast. "Existing material on T1 tended to suffer from one of two problems: it would get caught up in the engineering details and lose sight of the big picture, or it would ignore what new installations were used for. In either case, network administrators were left to suffer in darkness and ignorance. Very little of the existing written material on T1 is practical or suited for data network administrators." The knowledge needed to work with T1 is specialized and hard to come by in the outside world. T1: A Survival Guide brings together in one reference all the information network administrators will need to set up, test, and troubleshoot T1, including how to deal with routers, serial links, smart jacks, and more. A glossary of telecom terms helps administrators "speak the language" of the phone company when diagnosing and fixing T1 problems. This practical guide covers the following broad topics:

  • What components are needed to build a T1 line, and how those components interact to transmit data effectively

  • How to use standardized link layer protocols to adapt the T1 physical layer to work with data networks

  • How to troubleshoot problems and work with the telephone company, equipment manufacturers, and Internet service providers

T1: A Survival Guide will be useful to all network administrators who have any degree of responsibility for T1 lines. This diverse group includes smaller start-up companies using T1 connectivity, large companies employing a network of T1 lines, and service providers who do not use the lines directly but provide service over T1 to their customers (this group can be divided into telephone companies that provide T1 lines and Internet service providers that offer Internet connectivity over T1). A much needed resource, T1: A Survival Guide aims to take the guesswork out of using T1 as a data transport.

Online Resources:

T1: A Survival Guide
By Matthew Gast
September 2001
ISBN 0-596-00127-4, 288 pages, $29.95 (US)

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