Distributed buffer analyses in ATM routing structure when submitted to Unicast and Multicast cell traffics Carlos Antônio Ruggiero 1 , Angelo Cesar Colombini 2 1 Universidade de São Paulo - USP Instituto de Física de São Carlos Av. Dr. Carlos Botelho, 1465 - São Carlos – CEP 13.560-300 Estado: São Paulo - Brasil Telefone: (0xx16) 273.9879 Email: toto@if.sc.usp.br 2 Universidade de São Paulo - USP Instituto de Física de São Carlos Universidade de Franca - UNIFRAN Av. Dr. Armando Salles Oliveira, 201 – CxP. 082 Estado: São Paulo - Brasil Parque Universitário – Franca – SP – CEP 14.404-600 Telefone: (0xx16) 3711.8888 Email: angelo@if.sc.usp.br angelo@unifran.br Abstract Broadband Integrated Services digital networks (B- ISDN), have been extensively studied. The reason for is that the platforms are able to provide voice, data and video services simultaneously. Research on ATM has increased during the last years and one of the most emphatic points is the search for Multicast efficient solutions in ATM switches. ATM switches, although being an evolution of the traditional telephony switch, are much more than simple routing structures and cells buffers. In a network ATM, the switch stands out for performing a central role. Besides the cells retransmission functions, the switch should also accomplish control and management functions related to B-ISDN Control and Management Plans. All these functions make up the ATM switch. Architecture proposed for the cell structure switch is more specifically the cell routing inside an ATM switch. Because ATM tries to satisfy all the demands of the B-ISDN model, an ATM switch must transport cells between its input and output as fast as possible. To achieve that, the proposed architecture uses a simple shared Buffer strategy in its commutation elements. I. INTRODUCTION The proposed architecture was modeled and a simulator was constructed for testing purposes. For the simulations, both the unicast and the multicast traffics were taken into account. As the unicast and the multicast copies cells compete for the same output link, to solve this, a strategy was proposed to separate these cells. It resulted in the cell copy network position in the second stage of the routing structure; the first stage was left for the unicast routing cells. The result of this is that the second stage is available for copying multicast cells. This new phase reduced the contention for an outlet link. The structure incorporates the concepts of Tandem Banyan Switch Fabric (TBSF), and route duplicity, which make it extremely modular and flexible. To separate the traffic, it was introduced between the two Banyan Network stages, an escape outlet, allowing cells that have reached the correct output to leave the structure. Because the Banyan networks have less than N 2 crossing points, it is possible that two cells with different output destinations contend for the same channel before the last switch output block. In this case, only one cell will get to the next phase. To minimize this problem, a Batcher network classification is added to rearrange the cells in increasing address in order to serve the Multicast request, cell copies should be generated inside the routing structure. The consequence is a control complexity increase, a memory usage and a reduction in throughput. Our research simulates and analyzes a new ATM switch routing structure that uses the Batcher and Banyan network concepts. This ATM switch routing structure is organized in a distinct way, with a new-shared Buffer being added and distributed along each routing element that composes the Cell Switch Fabric. They are many proposals to make the traffic multicast in the ATM switching more efficient. Some of them use the duplication cell approaches. The multicast cells are duplicated and directed as unicast cells. On the other hand, others use the sharing buffer in the routing structure output as an assisting the multicast [1] form. Based on the package copy methods, the multicast switching architecture can be divides in two groups: multicast tree and the broadcast [2]. The switching based in the beginning multicast tree, consists in two stages. The first one is a network copy for the cell duplication and the second a routing network with the