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T1: A Survival Guide
What a great age we live in, where you can teach YOURSELF your entire profession! As a self-taught network engineer with a major market data firm, I have great respect for some of today's tech writers who have single handedly taught me TCP/IP, Ethernet, Cisco routers, and Linux! The only aspect of my job for which I have had to rely solely on experience, (and the meager amount of information on the web) is T1s and synchronous circuits/leased lines. As far as I know, the only books which discussed the technical details of T1 and synchronous circuits are general telecommuncations text books. None are written from a contemporary network administrator's point of view. So, you understand my excitement at seeing O'Reilly take a stab at just such a book!
The book starts off at a good pace, talking about the history of the telephone network and its evolution into the digital age (the reason we have T1 available as a data service). It discusses the different terminology related to T1's, and the equipment that connects them to our routers, but makes very few analogies or examples to solidify the relationship of these terms to each other or to the big picture of networking. After discussing the physical and logical layout of T1 and its physical interface with our routers, Gast spends the next 40 pages on the nitty gritty details of T1: Timing, Framing, Coding, and the lights on the CSU/DSU. All the important aspects of T1 are discussed in a logical order. Unfortunately, it's not enough; Gast breezes through the most important and mysterious aspects of T1 without so much as one good analogy or explanation to develop the ideas. The diagrams are equally disappointing. They have a lot of information, but do little to clarify the subject matter. The T1 framing sections, especially did not get enough attention. This is the heart of T1, and really wasn't explained well enough.
After getting what seemed to be an introduction to the subject matter, I expected the rest of the book to go into further detail about the intricacies of T1 framing and coding, and ways to hash out possible problems on T1 circuits. Instead, the next 60 pages give the boring and useless details of the three most common link-layer protocols run over T1s: HDLC, PPP, and Frame Relay. Gast continues to litter the pages with confusing and uninformative diagrams, and then spends time explaining the details of each one step-by-step. Good diagrams don't need step-by-step explanation; they speak for themselves!
The level of detail he goes into for each of these protocols is similar to what you might find in a general Data Networking text. He discusses different principles of data communication as well as the specific frame formats of these protocols, but doesn't explain how these protocols specifically interact with T1. Although he gives the frame formats of these different WAN protocols, he doesn't give enough information or suggestions on using the information in any effective way. The oversimplification of many of the diagrams makes the book less useful than the RFCs which will give you the exact frame formats.
Gast assumes that if you don't work for one of the telcos, the only way you may come across a T1 is as a small business network administrator responsible for maintaining internet access via T1. That is not the case anymore; many large companies manage their own backbone and have access to leased lines, and T1 testers. The only time a T1 tester is mentioned, it's described as 'a handheld device with lots of buttons and blinking lights on it.' The principles behind T1 testing are quickly covered, but the intricacies of testing T1s and using T1 testers are not. This is unfortunate, as many Cisco routers have built in test pattern generation and loopback capabilities! (As do most standalone CSU/DSUs.)
It's obvious, as it is in many poorly written tech books, that the author knows his subject! The problem is, he doesn't consider the fact that we, the reader, may not. The book wasn't a complete waste of time; there is a lot of good information in here. Information on signaling and different types of alarms on T1s is present. The majority of it is just not explained very well, and too much time is spent on the link-layer protocols. I probably wouldn't be so down on this book if it didn't have O'Reilly's name on it.
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It's a well known fact that people who know a lot about a subject, and may be able to answer any question you may have if you ask them, simply can't write a book or teach a class to save their lives. Extensive knowledge does not always lead to ability to teach. I'm sure the book is extremely informative for someone who would like a reference to things related to T1, but for someone who wants to actually learn it (Such as myself), this would probably be a very difficult read at best.
I think I concur with the author in that, if it wasn't an O'reilly title, which has a history of good explanations and good writing, then it wouldn't be such a problem.
Randal Graves says: I'm a firm believer in the philosophy of a ruling class... Especially since I rule.
Well it is a real disturbing tendency to pick up the book coz of a big name. and the publishers know of this. Go to their website and check out some new books. most of them are nothing compared to what we used to get a couple of years ago. The big publishers are gettin compalacent or what. Coming out with a book for the heck of it! Another thing i have noticed in all O'reilly books, infact in all big names, that the first chapter is the same. History, then a little bit of introduction and finally all of a sudden you are in a maze! I Dunno what happened to the Days of the Perl CookBook!
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Since time immemorial, the principle of being self taught has been prevalent throughout society. Especially in the arts, but also in Sciences, where people read books and all that and became famous without any professional qualification.
The difference with Internet, is that you can learn about it by using it, from anywhere, at the same time as everyone else, and it truly is becoming a universal skill.
But in all, apart from overuse of the exclamation mark, a reasonable review.
Conversion Rate Optimisation French / English consultant
It's immense, it is not intended to be the "gimme a quick answer right away because I have no patience" type of website. It is much like an engineering college's research library and as such, it needs to be studied thoroughly, and learned how to be used before using it. Once you've mastered the usage of CCO, you will then have achieved a well-founded education in Cisco's world of datacomm technology.
Maybe you should e-mail the author and let him know what you thought about the book- who knows, maybe it will inspire him to do a second edition that will address your concerns.
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I had all kinds of trouble googling for info on a "T-bird tester" until I figured out it was actually a T-Berd...
. We've got computers, we're tapping phone lines, you know that ain't allowed - Talking Heads, "Life During Wartime"