A self-healing ring, or SHR, is a telecommunications term for loop network topology, a common configuration in

telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

transmission systems. Like roadway and water distribution systems, a loop or ring is used to provide redundancy. SDH,

SONET Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diode ...

and WDM systems are often configured in self-healing rings.

Description

The system consists of a ring of

bidirectional Bidirectional may refer to: * Bidirectional, a roadway that carries traffic moving in opposite directions * Bi-directional vehicle, a tram or train or any other vehicle that can be controlled from either end and can move forward or backward with e ...

links between a set of stations, typically using

optical fiber An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass ( silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a mea ...

communications. In normal use, traffic is dispatched in the direction of the shortest path towards its destination. In the event of the loss of a link, or of an entire station, the two nearest surviving stations "loop back" their ends of the ring. In this way, traffic can still travel to all surviving parts of the ring, even if it has to travel "the long way round". A second break in the ring may divide it into two sub-rings, but in such a case each sub-ring will remain functional.

Advantages

Self-healing rings offer high levels of resilience at low cost, since it is often geographically easy to take multiple paths across the landscape and link them up into a ring with very little extra fiber length. Recent submarine communications cables are typically built in pairs to function as a self-healing ring. Very high resilience systems are typically built on interconnected meshes of self-healing rings. Another example of a self-healing ring network technology is the

FDDI Fiber Distributed Data Interface (FDDI) is a standard for data transmission in a local area network. It uses optical fiber as its standard underlying physical medium, although it was also later specified to use copper cable, in which case it m ...

local-area network.

Resilient Packet Ring Resilient Packet Ring (RPR), as defined by IEEE standard 802.17, is a protocol designed for the transport of data traffic over optical fiber ring networks. The standard began development in November 2000 and has undergone several amendments since ...

is a new technology for packet-switched self-healing ring networks.

Description

Advantages

See also