Tokenläbimise

Tokenläbimise is a term originating from Estonian, often translated as "token passing" or "token passing protocol." It refers to a specific method used in computer networking, particularly in older token ring network topologies, to control access to a shared communication medium. The core principle involves a special frame, known as a "token," that circulates around the network.

A node on the network can only transmit data when it possesses the token. When a node receives the token and has data to send, it captures the token, attaches its data to it, and then sends the combined frame onto the network. Other nodes receive this frame, check if it's addressed to them, and if not, pass it along. Once the frame has completed its circuit and returned to the originating node, that node removes its data and releases a new, free token back into circulation.

This mechanism prevents data collisions, a common problem in shared network environments where multiple devices might attempt to transmit simultaneously. By ensuring only one device can transmit at a time (the one holding the token), tokenläbimise provides a deterministic and orderly way to manage network traffic. While token ring networks are less common today, the concept of token passing has influenced other networking technologies and access control methods.