ringnetwork

A ring network is a network topology in which each node connects to two others, forming a closed loop. Data travels around the ring in a single direction or in both directions depending on the protocol. In traditional ring networks, access to the network is controlled to avoid collisions.

In token ring implementations, a control frame called a token circulates around the ring. A node that has data to transmit must wait for the token, seize it, send its data, and release the token back into the ring. This approach yields a deterministic access method and can reduce collisions.

Common forms include IBM Token Ring (IEEE 802.5) and fiber-based implementations such as FDDI, which used dual counter-rotating rings for redundancy and higher speeds. Active rings use intelligent network devices at each node to regenerate signals and maintain ring integrity, while passive rings simply repeat signals and rely on external devices to manage failures.

Advantages of ring networks include predictable performance and straightforward collision avoidance, while disadvantages include vulnerability to a single node or link failure and challenges scaling beyond moderate sizes. Modern Ethernet networks, which rely on switching in a star topology, have largely displaced ring topologies, though some metro networks and protection schemes still employ ring-inspired concepts such as dual rings or resilient packet ring in specific contexts.

See also: Token Ring, FDDI, resilient packet ring, network topology, IEEE 802.5.