This excellent supplement to the IEEE 802.5 token ring standards outlines the evolution of the token ring protocols from the very beginning to the present and provides insight into the decisions made during that evolution. The authors' direct involvement in the evolution of the token ring enables them to provide anecdotes that help readers to understand and appreciate the current status of token rings. The book also touches on the competition between the token ring and Ethernet protocols and provides background information about the current market share of each protocol. The book consists of six chapters and five appendices. Chapter 1 explains why IBM chose token ring and outlines the history of the protocol. Chapter 2 is devoted to token ring cabling and configurations. It addresses alternative transmission media and related specifications, the use of repeaters, and the logical design of token ring networks. Tables and examples help in understanding details of token ring design. The physical layer is addressed in chapter 3, which explains encoding and decoding, physical media components, and jitter accumulation. This chapter also highlights the use of the standards consensus process to resolve interoperability issues. Chapter 4 provides comprehensive information on all aspects of classical token rings. Equivalent information on dedicated token rings is provided in chapter 5. The last chapter discusses ongoing developments in high-speed token ring and stresses the economic battle between token ring and Ethernet. Although token ring is based on a superior design, Ethernet dominates the LAN market due to the lower prices of its components. The book highlights the fact that the development of the gigabit token ring will not be sufficient to maintain and expand the existing customer base of the token ring protocol; vendors will have to price token ring components aggressively. Appendix A provides excerpts from a paper on token ring local area networks and their performance. A paper on “Investing in Token Ring: A Guide for Network Managers” is reprinted in Appendix B. Appendix C is a paper on migration issues and strategies for token ring. Appendix D contains vector and subvector definitions, and Appendix E discusses the transmit forward process. The notes on issues addressed that are provided throughout the book should be a great help to readers. However, the book could be improved through careful editing. In a few cases, the text is not fully in line with the figures referred to, and in a number of cases text is unnecessarily repeated within a few pages. I highly recommend the book to readers who would like to study the token ring protocol and standards. It could be a valuable supplemental textbook in network courses. It could also serve as an authoritative reference for local area network designers and managers.
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This paper presents a hybrid architecture for local area networks (LANs) which combines the advantages of token ring and mesh networks while remaining relatively simple. Each node may have two communication channels. The first is a token ring and is .
The FDDI Token Ring Protocol controls communication over fiber optic rings with transmission rates in the range of 100 megabits per second. It is intended to give guaranteed response to time-critical messages by using a "timed token" protocol, in which .
CCITT Recommendation X.25 describes the interface to a public data network operating in the packet mode. However, it describes this interface almost entirely from the network's viewpoint. Investigations within ANSI X3S3 in 1980 showed that X.25 leaves .
