Detection of TCP Performance Degradation Using Link Utilization Statistics

Keisuke ISHIBASHI
Ryoichi KAWAHARA
Takuya ASAKA
Masaki AIDA
Satoshi ONO
Shoichiro ASANO

Publication
IEICE TRANSACTIONS on Communications   Vol.E89-B    No.1    pp.47-56
Publication Date: 2006/01/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.1.47
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
Keyword: 
TCP,  performance,  link utilization,  measurement,  

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Summary: 
In this paper, we propose a method of detecting TCP performance degradation using only bottleneck-link utilization statistics: mean and variance. 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 possible range of fluctuation becomes narrow and 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. In particular, this method enables a network operator to determine whether or not the degradation originates from the congestion of his/her own network. Because our method requires us to measure only link utilization, the cost of performance management can be greatly decreased compared with the conventional method, which requires dedicated functions for directly measuring the TCP performance.