Exponential Decay Queue Thresholds for Optimal Buffer Sharing

In an N x N shared buffer switch architecture, a common buffer space is shared among output ports, which provides flexibility in resource allocation. However the problem arises when the buffer space is dominated by one or more output ports in case of imbalanced input traffic. Thus this results in an increased packet loss rates due to unfair sharing of buffer space. For this reason buffer management policies are essential to regulate the buffer space occupied by active output ports. In this paper we introduce a dynamic threshold policy, which is inspired from the exponential decay. This policy suggests that the buffer space accessed by an output port decays exponentially with respect to its queue length. In this work we compare the packet loss rate performance of this scheme with the dynamic thresholds policy by carrying out a simulation study. We have shown that the performance of the exponential decay function policy can be improved by considering unused buffer space. It is found that the improved policy achieves the same packet loss rate as the dynamic thresholds policy with an improved buffer utilisation. The results suggest that the best threshold based buffer management policy is the one that allows buffer overflow in the case of hotspot packets.