Ring topology

In short: In a ring topology every device is connected to exactly two neighbours, forming a closed circle.

In more detail: Data moves in one direction from device to device until it reaches the recipient. A well-known method was Token Ring (IEEE 802.5): only the holder of the “token” (a permission to send) may transmit, so there are no collisions.

In Depth

• Advantages: orderly access, predictable response times, good for long distances.
• Disadvantages: if a device or a line fails, the ring can be interrupted. Adding devices briefly interrupts operation.
• Dual ring: FDDI and modern fibre rings use two counter-rotating rings. If one breaks, the network switches to the other.
• Today: no longer common in office LANs, but widespread in rings of MANs and provider networks.

See also: network topologies, star topology