[techbooks] REVIEW: "IP Telephony", Olivier Hersent/David Gurle/Jean-Pierre
- BKIPTLPH.RVW 20000216
"IP Telephony", Olivier Hersent/David Gurle/Jean-Pierre Petit, 2000,
%A Olivier Hersent book@...
%A David Gurle
%A Jean-Pierre Petit
%C P.O. Box 520, 26 Prince Andrew Place, Don Mills, Ontario M3C 2T8
%I Addison-Wesley Publishing Co.
%O 800-822-6339 617-944-3700 Fax: (617) 944-7273 bkexpress@...
%P 456 p.
%T "IP Telephony: Packet-Based Multimedia Communications Systems"
The preface does a rather heavy-handed sell on IP telephony, without
really backing up any claims. It doesn't really define a specific
audience, although the set of people who are listed as possibly being
interested is a fairly limited one.
The preface also expects a strong familiarity with ISDN (Integrated
Services Digital Network) and TCP/IP networking. I'm not sure that I
understand the requirement for ISDN, but a strong technical background
is a must, if you are going to tackle this book. The authors don't
appear to have made much attempt to ensure that it is readable, or
even lucid. The text resembles nothing so much as a mass of technical
trivia, only nominally organized. Ironically, despite the heavy
technical content, there does not seem to be enough detail in the work
to ensure that even dedicated readers will be able to produce some
kind of implementation.
Section one supposedly talks about application layer IP telephony
protocols, although much of the material appears to be more
appropriate to the session layer. Chapter one is huge, touching on
the H.323 standard, RTP (Real-time Transfer Protocol), security,
codecs, and an extensive H.323 session walk-through. The alphabet
soup is thick, and not always defined. RAS (Registration,
Application, Status, in this case) is not expanded at any point prior
to page six, where it is used for the first time and noted as being
defined "above," although it is based on H.225.0 which gets mentioned
"above." H.323 is a complex standard which is somewhat non-standard,
but the lack of any logical progression in the writing is not going to
help the reader follow the material. The Session Initiation Protocol
(SIP), in chapter two, appears to be something of an Internet-based
contender to the ITU's (International Telecommunications Union) H.323.
The Media Gateway Control Protocol (MGCP) seems to be a broader
technology in some competition and cooperation with both, in chapter
Section two looks at voice technology. Chapter four touches on a
number of topics related to voice quality, but mostly concentrates on
delay. Lots of math, tables, and flowcharts fail to explain much
about voice coding in chapter five, which primarily seems to be a
historical progression of standards.
Section three discusses the network. Chapter six talks about quality
of service (again emphasizing delay). Network dimensioning, in
chapter seven, provides lots of math for figuring out the minimum
bandwidth you need. IP multicast routing is the topic of chapter
Ultimately, this book might be most useful as a pointer to other
sources of information, such as the standards themselves.
copyright Robert M. Slade, 2000 BKIPTLPH.RVW 20000216
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