Token Ring3-9Technology BasicsToken RingAbstractToken Ring is a networking technology developed in the early 1970s byresearchers in Sweden and the United States. The technology was embraced byIBM, and was standardized in 1985 by the IEEE 802.5 group. The Token Ringstandard is often referred to as the IEEE 802.5 standard.Token Ring LANs provide an operating bandwidth of either 4 Mbps or 16 Mbps.The throughput which the network will provide is determined when the networkis designed.Token Ring is very popular with companies or facilities requiring fault toleranceand guaranteed throughput under heavy network loads. Customers such asInsurance Agencies, Banks, or Sales Organizations, which have regularhigh-usage periods where delay is detrimental to profit, or mission-criticalnetworks for facilities such as hospitals, often find Token Ring to be morebeneficial than Ethernet, while being less costly to implement than the muchfaster Fiber Distributed Data Interface (FDDI) technology.TheoryToken Ring network operation is based on the principle that the operation of theentire network determines when a station may transmit and when it will receive.Stations monitor one another, and one station acts as a ring monitor, keeping trackof important statistics. Token Ring stations are connected to one another in apredetermined order, and network frames pass from one station to the next,following that order. A specific, specialized network frame (a collection of data),called a token, is passed around the ring at regular intervals. The transmission ofthe token helps establish some of the operational statistics for the network, andreceiving it allows a station to transmit.OperationRingsEvery station that connects to a Token Ring network is a member of a ring. Thering is made up of a series of stations which are connected to one another througha Token Ring device, and the cabling, or media which connects them together. Thering in Token Ring networks is a single network segment.
