token ring

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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.

Usenet newsgroup: news:comp.dcom.lans.token-ring.

Token Ring

A local area network (LAN) access method developed by IBM. Conforming to the IEEE 802.5 standard, Token Ring uses a token ring access method and 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 all Token Ring business networks have migrated to Ethernet.

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

Type 1 and Type 3
Type 1 Token Ring networks allow up to 255 stations per network and use shielded twisted pair wires with IBM style Type 1 connectors. Type 3 Token Rings allow up to 72 devices per network and use unshielded twisted pair (Category 3, 4 or 5) with RJ-45 connectors.

Like Ethernet, Token Ring is a data link protocol (MAC layer protocol) and functions at layers 1 and 2 of the OSI model. See data link protocol and OSI.

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.