Ethernet networks have become so common in the workplace and in laboratories that they are largely invisible. Like computers themselves, they work, and communication with colleagues around the world is now as easy as sending a message to the people in the next office.

The technology behind this, as we all eventually learn, is not infallible, and when the network goes down, much of the work we want to get through grinds to a halt. Our communications specialists appear at this point, finding the parts that have gone bad, making improvements, and installing new, faster, and more reliable components, and things soon start moving again.

This is a book to read to find out about the technology behind Ethernet networks, and to a lesser extent, to learn about other things such as token ring and System Network Architecture (SNA) networks. The emphasis is on Ethernets, of course, and their connections to the rest of the world.

The basic ideas behind Ethernet are simple but subtle, and it is easy to make mistakes in estimating such operating characteristics as the effective throughput and time delays. Networks are also complicated because of their interconnections with other networks, the use of different communication protocols, and the different characteristics of the media encountered. The creative developments and the new products introduced every day by manufacturers in this competitive market can make things difficult to understand.

This book treats the whole scene. There is a discussion of the physical layer and its impact on Ethernet technology. The data link layer is treated in some depth, and the differences between Ethernet and IEEE 802.3 are discussed at length. Internetworking, hardware and software products, repeaters, bridges, routers and gateways, and the protocols used by them are presented. Chapters cover routing methods and performance issues, network management, and future developments.

Everything seems to be treated at some level--this is the book’s greatest strength. Its weakness is that these levels are uneven and many readers will want to go further into certain aspects that are not covered deeply. They will be unable to use the references cited in the text because there are none. The explanations are nearly all descriptive, with few equations, tables, or graphs. This may be an advantage for the reader who wants a quick overview of various aspects of Ethernet, but it will be frustrating for the professional who senses that the author obviously knows more about the subject than he presents.

The chapter on network management may be a disappointment to those who have to actually manage a network. Four software tools--LightWatch, EtherVision, Frye Utilities for Networks, and NetWare Monitor--are discussed, but other references will be sought. An overview of some of the  simple  but useful protocols such as 802.2 TEST and a discussion of the more common DSAP addresses would have been useful.

The writing style is clear, easy to follow, and mercifully free of most of the technical jargon used by net experts. Both the index and the table of contents have been constructed well. Plenty of diagrams are included, and they are well keyed to the text. The book appears best suited to practitioners or other interested parties who do not want or need a rigorous study of Ethernet networks but who need to know how they work and what they can do.