The Token Ring is a Local Area Network (LAN) topological technology that was developed by IBM in the 1980’s as the standard for LAN design and architecture. It is a local area protocol which serves on the OSI Model at the Data Link Layer (DLL). The name derives from a special three-byte frame or packet called a “token” that loops around the entire network, carrying data around the network in every loop. It was a standardised IEEE 802.5 technology when IBM (International Business Machines) applied for the patent and was initially well received and used. However, with the advent of Ethernet, the Token Ring was completely overthrown because of the speed and cost effectiveness of Ethernet over the Token Ring’s collision free architecture. Eventually only IBM was left with a working Token Ring network and soon that was also lost in the tide of the Ethernet.
The working of the Token Ring system is usually a process of trial and error, i.e. the data issued or ordered for by the router does not automatically go to the correct client – the data starts its loop from the router to the first computer and checks if the address of the asking computer matches with the computer at hand. If it does, then it processes the input and sends some data over the frame which then completes the loop asking for other nodes’ input or output if any. If the asking computer’s address does not match with the supplied address, the frame goes to the next computer and asks for the same. This procedure makes the token a sort of a “vessel” that transports the data around the entire network. This process, though not without its advantages had significant data speed loss disadvantages as the node with a token containing the address of its nearest downstream node will not transmit it back towards it, but will ensure that the entire loop is traversed by the token.
Initially marketed at a speed of 12 Megabits per second (12 Mbps) the Token Ring architecture advanced sufficiently to 16Mb/s to 100 Mb/s (during its wane and Ethernet’s wax) to an un-marketed standard of 1000Mb/s by IEEE in 2001. Initially marketed and claimed to be much faster and better than the Ethernet, the use of these Token Rings fell when switched Ethernets came into use – providing better speeds and higher collision detection and collision avoidance methods that outshone the Token Ring.
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