Efficient isochronous traffic management in DQDB

The pre-arbitrated scheme in the DQDB network is suitable for constant-rate and connection-oriented transmission. The authors propose a periodic assignment scheme, which classifies isochronous connections into several harmonic classes according to their periods. The main advantage of the proposed scheme is that by assigning the same unit channel to connections of the same class, these connections can be established as long as the total required bandwidth is no greater than the available bandwidth of the unit channel. The authors study three assignment policies based on the harmonic case of the pinwheel algorithm. These assignment policies are evaluated in terms of their blocking probabilities through both simulation and analysis. It is found that the busy-first policy, which tries to assign a new isochronous connection with a unit channel already carrying other connections of the same class, is the most suitable one.