BKFDDIHB.RVW 940422 Addison-Wesley Publishing Company P.O. Box 520 26 Prince Andrew Place Don Mills, Ontario M3C 2T8 416-447-5101 fax: 416-443-0948 Heather Rignanesi, Marketing, x340, 73171.657@Compuserve.com or Tiffany Moore, Publicity tiffanym@aw.com Bob Donegon bobd@aw.com John Wait, Editor, Corporate and Professional Publishing johnw@aw.com Tom Stone, Editor, Higher Education Division tomsto@aw.com Philip Sutherland, Schulman Series 74640.2405@compuserve.com Keith Wollman, Trade Computer Group keithw@aw.com Lisa Roth Blackman, Trade Computer Group lisaro@aw.com 1 Jacob Way Reading, MA 01867-9984 800-822-6339 617-944-3700 Fax: (617) 944-7273 5851 Guion Road Indianapolis, IN 46254 800-447-2226 "FDDI Handbook", Jain, 1994, 0-201-56376-2, U$49.50 jain@acm.org "Radio waves" are electromagnetic distortions travelling through the "ether" (basically, nothing) or wires. Radio can be modulated or encoded to carry information. Light is electromagnetic radiation as well, but of a higher frequency. Because of the higher frequency, light can be used to carry much more information than radio. There are only two problems: light is unsuitable for broadcasts because of very high power requirements; and, light can't travel over wires. Light travels in straight lines. At least, that is what everyone knew until the nineteenth century, when it was observed that light would follow the path of a curving stream of water. When light passes from one medium to another, there is always some reflection. However, when light comes from a medium with a high index of refraction (like water) to a boundary with a lower index of refraction (like air) there can be what is known as total internal reflection. (Try looking through the side of an aquarium and out the top. Can't be done.) This means that a "wire" of glass with a high refractive index running through a thicker "wire" of lower refractive index will carry light from end to end, in spite of curves in the fibre. Now you know something about fibre optics. There is still an awful lot to know about how it works in practice, what the protocols are, how to control access to the media, how to interconnect it with copper cables, how to manage it, how to buy and install it, and how well to expect it to perform. Which is what this book is about. Fibre Distributed Data Interface (FDDI) is the standard for local fibre optic communications circuits. Jain gives a wide-ranging coverage of related topics. The book is said to be suitable for users, buyers, managers and designers of computer networking products. This would be true of users, buyers and managers who were engineers. The book is primarily technical in nature, although there are some sections dealing with evaluation and purchasing guidelines. Jain tries to lighten the tone with cartoons and humorous sidebars. While cute, these do not add to explanations in the book. In common with most technical books, there is an attempt to promote its use as a text by the inclusion of "exercises". These are, as usual, extremely simplistic. Fibre has many advantages over copper. Silica is much more abundant than copper. Fibre is lighter and can carry more data farther, with less power expenditure. Fibre has potentially much greater bandwidth than copper (although the recent 100 megabit per second - Mbps - ethernet is equal to the FDDI standard). Jain is clearly on the fibre bandwagon. He goes a little overboard at times. He repeats the refrain that fibre is more secure since it can't be read or modified without breaking the cable. (It can. It's hard, but it can be done. It's interesting that this statement comes immediately after a discussion of reliability functions which tend to make detection of a break less certain--and opposite a sidebar on network "religious" beliefs.) Jain also states that fibre is lighter and more flexible, and, therefore, easier to install. This is later (much later) contradicted by the fact that fibre cannot be fit into tight corners (it must have a large radius of curvature to function properly) and that fibre cable should be run through conduit inside stiff innerducts--thus eliminating the advantages of flexibility. (Some of Jain's sidebars give fascinating if not quite accurate information. Carrier Sense Multiple Access - CSMA - media access, the access method for Ethernet, is said to have been derived from the "Aloha" or "hello" access method. Ethernet owes some development, including CSMA, to Alohanet, the satellite link used from the University of Hawaii to the mainland.) A lot of valuable technical information, but the audience scope is not as broad as stated. copyright Robert M. Slade, 1994 BKFDDIHB.RVW 940422 ====================== DECUS Canada Communications, Desktop, Education and Security group newsletters Editor and/or reviewer ROBERTS@decus.ca, RSlade@sfu.ca, Rob Slade at 1:153/733 Author "Robert Slade's Guide to Computer Viruses" (Oct. '94) Springer-Verlag