Accurate bandwidth measurement in xDSL service networks

In xDSL service networks, accurate bandwidth measurement is essential for network management and traffic engineering, such as isolating line faults and verifying guaranteed quality of service specifications, where ISP and xDSL service providers may be involved. Existing Internet bandwidth measurement techniques are not suitable because link asymmetry and ATM traffic shaping in xDSL deployments impact the accuracy of their measurements. In this paper, we present a novel stepwise algorithm for bandwidth measurement that performs accurately in xDSL service networks. The stepwise algorithm requires a smooth traffic generator since otherwise the accuracy would be affected by the ATM traffic shaping. A multi-packet technique is used to avoid explicit packet filtering. The scheme is lightweight in terms of implementation complexity and probe traffic overhead. The accuracy of the algorithm is demonstrated by laboratory and field experiments. The results show that the measurement errors in both upstream and downstream cases are within the range of 5% in a commercial ADSL service network tested under the following ATM network configurations: CBR, rt-VBR, and UBR service categories. q 2002 Elsevier Science B.V. All rights reserved.