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Method of Bandwidth Dimensioning and Management for Aggregated TCP Flows with Heterogeneous Access Links Ryoichi KAWAHARA Keisuke ISHIBASHI Tatsuya MORI Toshihisa OZAWA Takeo ABE Publication IEICE TRANSACTIONS on Communications Vol.E88-B No.12 pp.4605-4615 Publication Date: 2005/12/01 Online ISSN: DOI: 10.1093/ietcom/e88-b.12.4605 Print ISSN: 0916-8516 Type of Manuscript: PAPER Category: Internet Keyword: TCP performance, processor-sharing model, heterogeneous access links, bandwidth dimensioning and management, Full Text: PDF(1.3MB)>>
Summary: We propose a method of dimensioning and managing the bandwidth of a link on which flows with heterogeneous access-link bandwidths are aggregated. We use a processor-sharing queue model to develop a formula approximating the mean TCP file-transfer time of flows on an access link in such a situation. This only requires the bandwidth of the access link carrying the flows on which we are focusing and the bandwidth and utilization of the aggregation link, each of which is easy to set or measure. We then extend the approximation to handle various factors affecting actual TCP behavior, such as the round-trip time and restrictions other than the access-link bandwidth and the congestion of the aggregation link. To do this, we define the virtual access-link bandwidth as the file-transfer speed of a flow when the utilization of the aggregation link is negligibly small. We apply the virtual access-link bandwidth in our approximation to estimate the TCP performance of a flow with increasing utilization of the aggregation link. This method of estimation is used as the basis for a method of dimensioning the bandwidth of a link such that the TCP performance is maintained, and for a method of managing the bandwidth by comparing the measured link utilization with an estimated threshold indicating degradation of the TCP performance. The accuracy of the estimates produced by our method is estimated through both computer simulation and actual measurement. | |||||
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