Detection of TCP performance degradation using link utilization statistics

In this paper, we propose a method of detecting TCP performance degradation using only bottleneck-link utilization statistics. The variance of link utilization normally increases as the mean link-utilization increases. However, because link-utilization has a maximum of 100%, as the mean approaches 100%, the variance decreases to zero. In this paper, using the M/G/R processor sharing model, we relate this phenomenon to the behavior of flows. We also show that by using this relationship, we can detect TCP performance degradation using the mean and variance of link utilization. Particularly, with this method, a network operator can determine whether or not the degradation originates from the congestion of his/her own network. Because our method requires us to measure link utilization only, the cost of performance management can be greatly decreased compared with the conventional method, which requires dedicated equipment to measure the network performance.