Realization of Non-Power-of-Two Distributors

This paper considers how to construct nonpower-of-two distributors, which concentrate and rotate, simultaneously, active input packets for an efficient buffer utilization in packet switching environment. As a theoretical background, we first establish that an R×R distributor cannot be constructed out of a conventional N × N distributor for a non-power-of-two number R in N 2 < R < N(= 2n), due to internal packet conflicts. We then consider how to resolve the internal packet conflict problem to construct a non-power-of-two distributor out of the nearest power-of-two distributor and introduce a number of possible arrangements. Especially, we present a single-CSE (Controlled Switching Element)-RBN (Reverse Banyan Network) based realization which helps to eliminate the dummy address calculation and generation operations that used to be required in the conventional RBN based distributors. Further, we extend the single-CSE-RBN based distributor to generate two flexible-size distributor structures—flexible R× R and N ×R distributors— which can respectively perform the R×R and N×R distribution functions for an arbitrary number R ≤ N simply by changing the CSE parameter setting. key words: ATM switch, packet concentrator, packet distributor