Abstract

Abstract—Counting Bloom Filters (CBFs) are widely used in networking device algorithms. They implement fast set representations to support membership queries with limited error, and support element deletions unlike Bloom Filters. However, they also consume significant amounts of memory. In this paper we introduce a new general method based on variable increments to improve the efficiency of CBFs and their variants. Unlike CBFs, at each packet arrival, the hashed counters increase by a hashed variable increment instead of a unit increment. Then, to query a packet, the exact value of a counter is considered and not just its positiveness. We present two simple schemes based on this method. We demonstrate that this method can always achieve a lower false positive rate and a lower overflow probability bound than CBF in large systems. We also show how it can be easily implemented in hardware, with limited added complexity and memory overhead. We also explain how this method can extend many variants of CBF that have been published in the literature. Last, using simulations, we show how it can improve the false positive rate of CBFs by up to an order of magnitude given the same amount of memory.

Citations