A Study on a Performance Improvement Algorithm in DQDB MAN

Abstract In this paper, a performance improvement algorithm in DQDB MAN (Distributed Queue Dual Bus Metropolitan Area Networks) being standardized by the IEEE 802 Committee is proposed. In DQDB MAN, it should be noted that transmission slots are never erased halfway the bus and are terminated at end of the bus. This paper proposes an algorithm for improving this point. At first, a special node called “erasure node” is introduced in a DQDB network for slot reutilization in the downstream side and the operation of the erasure node is described. In the latter half of the paper, the performance of this algorithm is estimated using a queueing model, where the M/G/1 queueing model is applied to the network model. Average and variance of queueing delay and transmission delay are calculated by this method. The results show the effectiveness of the proposed algorithm for improvement of the performance.