Topology Discovery In Resilient Packet Ring

Resilient packet ring (RPR) technology is optimized for robust and efficient packet networking over a fiber ring topology. This technology incorporates extensive performance monitoring, proactive network restoration, and flexible deployment capabilities. RPR networks have the ability to carry multiple services, including jitter- and latency-sensitive traffic such as voice and video in addition to Ethernet and Internet protocol (IP) services. RPR combines the best features of legacy synchronous optical network (SONET)/synchronous digital hierarchy (SDH) and Ethernet into one layer to maximize profitability while delivering carrier-class service. RPR is a new MAC protocol ,it is designed to optimize the data transport. It offers two key features that heretofore been exclusive to SDH/SONET: efficient support for ring topology and fast recovery from fiber cuts and link failures. At the same time, Packet Ring technology can provide data efficiency,simplicity,and cost advantages that are typical to Ethernet.The RPR Topology Discovery Protocol provides each station on the ring with knowledge of the number and arrangement of other stations on the ring. This collection of information is referred to as the topology image. Each station maintains its own localcopy of the topology image for the entire ring. Initially, the station's topology image contains information only about itself.Ring topology discovery is initiated only as needed. Local topology validation eliminates the need for acknowledgements or periodic broadcasts. No station acts as a master for the topology image or for the protocol. All ringlet segments that can be discovered are included. A fully connected ring is not needed for the protocol.In addition to station identifiers and physical connectivity relationships, the topology discovery protocol is also used to propagate additional station information, both that which is used for other parts of this standard, and optionally information beyond the standard. The messages sent as part of the RPR Topology Discovery Protocol are indicated in the RPR frame header as control frames.