DYNAMIC BUFFER MANAGEMENT SCHEME FOR ATM SWITCHES

摘要

A buffer management scheme for a shared memory in an ATM switch sets different dynamic thresholds (18) for different Vcs (10) according to the formula: Tsub i (U) = Tsub Fsub i + gama sub i . (B - U) where B is the total size of the shared buffer and U is the size of the used portion of the buffer. According to the invention, Tsub i (U) is the threshold (in number of cells) for the ith connection when the used portion of the buffer is U, Tsub Fsub i is the required buffer allocation (in number of cells) for the ith connection buffer when the buffer is full and gama sub i is a power of two chosen for the ith connection at the time the connection is set-up. Both Tsub Fsub i and gama sub i are chosen based on the service category of the connection (12). In addition, the buffer management scheme sets minimum and maximum buffer sizes based on the service category of the connection. Preferably, a minimum buffer is guaranteed for service categories above UBR (unspecified bit rate). For UBR traffic, the minimum buffer available is determined by the number of backlogged connections. The maximum buffer size for each connection is a function of the total buffer size B, Tsub Fsub i and gama sub i.