Distributed-queue dual-bus network

In telecommunication, a distributed-queue dual-bus [network] (DQDB) is a distributed multi-access network that (a) supports integrated communications using a dual bus and distributed queuing, (b) provides access to local or metropolitan area networks, and (c) supports connectionless data transfer, connection-oriented data transfer, and isochronous communications, such as voice communications.

Source: from Federal Standard 1037C