token ring

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Related to token ring: Token Bus, Token ring connector

token ring

A computer local area network arbitration scheme in which conflicts in the transmission of messages are avoided by the granting of "tokens" which give permission to send. A station keeps the token while transmitting a message, if it has a message to transmit, and then passes it on to the next station.

Often, "Token Ring" is used to refer to the IEEE 802.5 token ring standard, which is the most common type of token ring.

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This article is provided by FOLDOC - Free Online Dictionary of Computing (

Token Ring

An earlier local area network (LAN) access method developed by IBM. Conforming to the IEEE 802.5 standard, the Token Ring access method connects up to 255 nodes in a star topology at 4, 16 or 100 Mbps. All stations connect to a central wiring hub called the "Multistation Access Unit" (MAU) using twisted wire cable. Today, most Token Ring business networks have migrated to Ethernet.

Different than Ethernet
The Token Ring MAU may be a central hub, but it does not function like a shared Ethernet hub. Token Ring is more deterministic, which ensures that all users get regular turns at transmitting. With Ethernet, all users compete to get onto the network.

Type 1 and Type 3
Type 1 Token Rings allow up to 255 stations per network and use shielded twisted pair wires with IBM style Type 1 connectors. Type 3 allows up to 72 devices per network and uses unshielded twisted pair (Cat 3, 4 or 5) with RJ-45 connectors. Like Ethernet, Token Ring is a data link protocol and functions at layers 1 and 2 of the OSI model. See token passing, data link protocol and OSI model.

Token Ring Topology
Token Ring uses a logical ring topology, which provides more equal opportunity for each station to gain access to the network than the broadcast method used by Ethernet. All nodes connect to the MAU.

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References in periodicals archive ?
Pre-orders are currently up for the Token ring (in United States sizes of 6 to 12) and it will cost early adopters $249 a piece.
Integrating Token Ring and Packet Reservation Multiple Access (PRMA) Protocols
Simon Drennan, director of marketing at Madge Networks, added: "This announcement provides Madge and IBM customers with an opportunity to boost the throughput between Token Ring and the IBM zSeries enterprise e-business server range.
"Madge has taken the lead in driving down the cost of Token Ring switching.
The IEEE 802.5 (ANSI/IEEE 1989) standard has become a widely accepted protocol for token ring local area networks.
Also called Token Ring, it differs from the bus method in another important aspect.
For example, both token ring and Ethernet can work with Netware because the choice of network interface card is separate from the choice of network operating system.
Our first example is the famous Dijkstra's token ring algorithm [Dijkstra 1985].
The network version would also require a server with Novell, 3Comm, IBM Token Ring, or other NetBIOS-compatible network(, and a 2x ISO 9660compatible CD-ROM drive.
Information is exchanged between these four PCs over a token ring network.
Within the technical center, a local "token ring" network connects the staff there to one another.