Telecom/1996-04-telecom-walnutcreek.iso/book.reviews/fddi.handbook-jain

Internet Message Format | 1995-01-05 | 5KB

Date: Sat, 16 Jul 1994 18:11:29 MDT
From: Rob Slade <[e-mail]>
Subject: Book Review: "FDDI Handbook" by Jain


BKFDDIHB.RVW  940422

Addison-Wesley Publishing Company
P.O. Box 520   26 Prince Andrew Place
Don Mills, Ontario  M3C 2T8
416-447-5101  fax: [phone]
Heather Rignanesi, Marketing, x340, [e-mail]
or
Tiffany Moore, Publicity  [e-mail]
Bob Donegon  [e-mail]
John Wait, Editor, Corporate and Professional Publishing [e-mail]
Tom Stone, Editor, Higher Education Division  [e-mail]
Philip Sutherland, Schulman Series [e-mail]
Keith Wollman, Trade Computer Group [e-mail]
Lisa Roth Blackman, Trade Computer Group [e-mail]
1 Jacob Way
Reading, MA   01867-9984
800-822-6339  617-944-3700
Fax: [phone]
5851 Guion Road
Indianapolis, IN   46254
800-447-2226
"FDDI Handbook", Jain, 1994, 0-201-56376-2, U$49.50
[e-mail]

"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.