The double-slot slotted ring protocol (DSR)

The DSR protocol combines a multilevel priority and fairness guarantee mechanism over a destination-release slotted ring. The fairness mechanism ensures fair bandwidth division within each priority level and operates through a distributed reservations algorithm entirely within the media-access control layer. In common with other destination-release slotted rings, the DSR protocol can offer network bandwidth which exceeds the channel bandwidth. However, unlike some quota-based load-balancing mechanisms, the DSR priority mechanism is effective, even when supporting bursty sources at high priority. There is no rule restricting one transmission per ring revolution. Therefore the protocol efficiency is virtually independent of the number of slots and the ring latency. The DSR protocol is therefore not only for LAN (local area network) applications, but for multimedia, metropolitan area applications, supporting in excess of 100 km of fiber and line rates in the gigahertz region