The IEEE 802.6 physical layer convergence procedures

An innovative distributed queue dual bus (DQDB) concept for media access control is the subject of a standardization effort by IEEE Subcommittee 802.6, which has been assigned the task of developing a standard to meet metropolitan area network (MAN) requirements. A unique characteristic of the DQDB standard that differs from the other IEEE 802 (local area network) standards is its intent to support a relatively large set of physical layer interface rates. The viability of the large variety of rates and formats is permitted by physical layer convergence procedures (PLCPs), which provide adaptation functions between a single common DQDB layer and the supported transmission systems. An overview of the dual bus structure of a DQDB subnetwork and background information on the DQDB layer services are provided. The PLCPs are defined in more detail, and the PLCPs for public network transmission systems and customer premises extensions are examined. An example of a stable DQDB subnetwork that experiences a link failure is described.<>