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DPT is a SONET-like technology that transports packets across fiber-optic rings. Along with Gigabit Ethernet and DTM (Dynamic Synchronous Transfer Mode), Cisco's DPT is considered one of the technologies to use in new fiber-access metropolitan area networks. It provides the reliability and restorability associated with SONET and SDH networks, but is specifically designed for packet transport. Cisco labels the technology as "IP+Optical." Some of the features of DPT are listed here:

• Transports packets between Cisco DPT routers over two counter-rotating OC-12 fiber-optic rings.


• Both fibers are used concurrently to transport both data and control traffic, unlike SONET, which keeps one in standby mode until needed.


• DPT uses SRP (Spatial Reuse Protocol) as a media access protocol. SRP manages the add/drop process, controls bandwidth, and controls the propagation of messages on the packet ring.


• Cisco claims throughput is double what SONET can provide over the same ring.

The Cisco Web site listed on the related entries page provides more information. You can also refer to "MAN (Metropolitan Area Network)" for information about metro access technologies in general.

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