A technology defined by the IEEE 802.6 standard for metropolitan area networks (MANs), as a means of extending the reach of a local area network (LAN) across a metropolitan area.The original work on the DQDB concept was done at the University of Western Australia where it was known as Queued Packet Synchronous Exchange (QPSX). Subsequently, Switched Multimegabit Data Service (SMDS) evolved from these efforts.This technology is considered obsolete. See also 802.6, IEEE, LAN, MAN, and SMDS.
(Distributed Queue Dual Bus) The protocol used to control access to an IEEE 802.6 queued packet synchronous exchange (QPSX) network, used for metropolitan area networks (MANs). This architecture allows for both circuit and packet switching and supports data, voice and video traffic. Using fixed length cell relay technology, DQDB is suited to volatile network traffic.