Saturday, November 26, 2011


Token Ring:

A big competitor to Ethernet in the past was Token Ring, which runs at 4 Mbps or 16 Mbps. Token Ring is a network architecture that uses a star ring topology (a hybrid, looking physically like a star but logically wired as a ring) and can use many forms of cables. 

IBM Token Ring has its own proprietary cable types, while more modern implementations of Token Ring can use CAT 3 or CAT 5 UTP cabling. Token Ring uses the token-passing access method. 

Looking at Token Ring networks today, you may wonder where the “ring” topology is, because the network appears to have a star topology. The reason why it appears that this network architecture is using a star topology is that all hosts are connected to a central device that looks similar to a hub, but with Token Ring, this device is called a multistation access unit (MAU or MSAU). . The ring is the internal communication path within the wiring. 

Token Ring uses token passing; it is impossible to have collisions in a token-passing environment, because the MAUs do not have collisions lights like an Ethernet hub does (remember that Ethernet uses CSMA /CD and there is potential for collisions).

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