Modeling and simulation of a validity count flow control mechanism for ATM networks

Flow control is one of the mechanisms employed to prevent and manage congestion in ATM networks. Rate-based flow control and credit-based flow control are the two best known schemes, and are widely implemented in commercially available ATM equipment. None of them entirely satisfies the requirements of flow control for LAN and WAN environments simultaneously, but each one has their key advantages. This situation has originated proposals for integrated rate-credit mechanisms as an alternative for operation in mixed environments. One of these schemes is the validity count, proposed by Ramakrishman (1995), where Resource Management (RM) cells would be employed to convey rate (the circuit transmission rate) and credit (number of cells that can be transmitted at that rate) information. In this work, a validity count flow control mechanism, able to generate and handle credit and rate information, is designed and modeled. Its use in ATM networks was simulated to assess its performance. Interoperability between different kind of switches and a satisfactory use of the links were observed