A comparison of FDDI asynchronous mode and DQDB queue arbitrated mode data transmission for metropolitan area network applications

The performance of the FDDI token ring and IEEE 802.6 DQDB protocols are compared using discrete event simulation models. A metropolitan area network (MAN) of 100 km and with 50 stations was modeled. A 100 Mbps channel is used for both networks with a traffic model with large (1 kbyte) low priority packets and smaller (100 byte) high priority packets. The delay and fairness characteristics of both networks are analyzed. The simulations show that FDDI has advantages in fairness and maximum capacity, while DQDB offers lower delay at all except very heavy loads and has a stronger priority mechanism.< >