In this paper, performance enhancement algorithm in DQDB MAN (Distributed Queue Dual Bus Metropolitan Area Networks) is proposed. DQDB which is standardized by IEEE 802 committee is one of protocols which provide medium access control in metropolitan area networks. In DQDB MAN, a fixed-length slot is a unit for transmission and exchange. Information is transfered by using the slot. The transit delay of the slot has to be small since the slot is not stored in each node. However, the slot having finished information transfer can not be reutilized in downstream nodes. This problem has been discussed by IEEE 802 committee and some societies. This paper proposes new algorithm for improving this point and shows implement scheme to realize it. At first, in this paper, a special node called an erasure node is introduced in a DQDB network and its operation is described. Moreover its implement scheme is shown. In the latter, the performance of this algorithm is evaluated using a queueing model. The result shows the effectiveness of the proposed algorithm.