This book explains: 1) various network technologies that are in use today, 2) various SNMP standards and tools that manage those technologies, and 3) strategies and hints for how to solve real problems with those tools. The book is divided into three major sections: Part 1, the basics of network management; Part 2, managing wires; and Part 3, managing hosts and network services. The authors developed their own API (application programmer’s interface), taking into consideration what I call the “4 es and a g” criteria for a good programmer’s language: embedded, extensible, existing and widely used, easily learned, and one that has a high-level graphical toolkit.
Examples presented are those of tools written with Tcl and the Tk toolkit so that readers can see how network management applications work while seeing a picture of that application in action. Despite the numerous examples to make concrete the general strategies that are presented in the book, the authors should have gone further for the layperson and used more practical examples. Sometimes they are close to enlightening but fall short of what one meets up with daily in dealing with the campus network as a user rather than as a network manager or coordinator. The authors themselves admit that they couldn’t possibly cover every networking technology in this book. Thus, the constant hint of a future book to cover additional technologies.
The aspect of the book that was of most interest was the third section, which takes a look at how hosts and network services are managed. These are the more practical portions of this practicum for a user. This section serves two purposes: it reinforces some of the things already learned while at the same time adding new knowledge that one would not otherwise have gone out of the way to know about.
One of the major problems that I have become aware of as a result of keeping up with the literature on worldwide networks is the fact that “whilst the original designers of the IP address developed a flexible scheme for allocating the 32 bits using address classes, the amount of flexibility has proved to be insufficient to cope with the phenomenal success and explosive growth of the Internet” (p. 171). “Even the introduction of the three-level address hierarchy…is proving inadequate to cope with the explosive growth of the Internet.” The problem occurs in two ways: insufficient usage of address space and rapid increase in the size of the routing tables in backbone routers (p.177). Such explanations have helped me address and understand the phenomenon in the Internet that I meet each day as I try to get my students more involved with using the Internet as a means of obtaining information. The book does point out that the nature of national and international communications traffic has changed. In the past, voice traffic was the major breakthrough and we have had to deal with problems associated with many subscribers to the new technology. Today, the fastest growing type of traffic is data communications, and we are encountering those same problems.
The authors have tried to outline the various types of errors that are encountered in data transmission. One learns that there are Internet control message protocols that determine what can be done if the message cannot reach the destination, when the time to deliver the message is exceeded, and so on. The transmission control protocol (TCP) entity cannot distinguish between not busy or congested networks and therefore several adaptive algorithms are used to determine the status and what activities will occur depending on the situation: retransmission, queued delivery, and dealing with urgent data.
Another interesting, controversial issue is identification: how do we deal with user information connected with the system? Implementation of identification is optional and controversial for two reasons: 1) information is only as trustworthy as the system running the agent and 2) information about the user can be considered private and therefore should not be broadcast over the net.
As the Internet becomes more and more prevalent internationally, it was enlightening to read some perspectives on wide area network management that need to be dealt with. We sometimes assume that making computers “talk” with each other across borders is a simple process not realizing that without standardization various protocols will have to be devised to communicate. The computer industry has to deal with internationalization (or i18n), referring to making systems natural language–independent and in fact there has been some support for a universal character set (see page 369). Such efforts remind me of attempts at arriving at a national language on a country level and official languages into which simultaneous translation takes place in the United Nations. Diplomacy in the computer industry entails knowing about international relations, since awareness of differences in culture, language, history, and technology is required.
This book (or a future effort) can be improved in several ways. If their aim is to really educate and not just preach to the choir, theoretical examples could be replaced by more practical examples. For instance, in citing what the computer does when errors are encountered or congestion takes place, actual examples of error messages can be used. Users can identify with these examples more than they would with the algorithmic logic that is used by the program.
A lot of paper is wasted on short tables that occupy only one-fourth of a page (but are given the whole page) and on brief sets of application lines of code. The book ends abruptly. It needs a conclusion or a summary of everything that has been covered, even though each chapter already has a summary.
Despite some of these minor flaws, the book is definitely educational and valuable for a better understanding of what goes into network management.
