A comparison of linear and mesh topologies-DQDB and the Manhattan street network

The authors make a performance and reliability comparison of two networks that have been proposed for use as high-speed metropolitan area networks (MANs)-the Manhattan street network (MSNet) and the distributed queue dual bus (DQDB) network. Both networks use slotted access protocols and have the same number of links, transmitters, and receivers per node. The DQDB network has been adopted by the IEEE 802.6 committee as the metropolitan area network (MAN) standard. The authors demonstrate the relative superiority of the MSNet over the DQDB network. They show that the MSNet provides a much higher network throughput for a variety of traffic patterns-uniform and nonuniform. They also look at the reliability of both networks and show that the MSNet can survive more failures than the DQDB network and that failures cause a lesser performance degradation in the MSNet. It is also shown that higher-level mechanisms are required in the DQDB network to recover from link failures whereas deflection routing is sufficient in the MSNet