Evaluation of FAST TCP in Low-Speed DOCSIS-based Access Networks

There is strong evidence that the efficiency of the Internet is limited by its existing TCP congestion control system. A replacement, FAST, has been shown to improve performance in high-speed networks. In order to achieve widespread acceptance and standardisation, it must also be tested in environments more typical of the existing Internet. This paper experimentally evaluates the performance of FAST over a typical access link, with bandwidths of around 0.5-3 Mbps. Links both using the DOCSIS cable modem medium access control (MAC) protocol and simple low rate links were investigated. It is shown that the random delay introduced by MAC protocol of the cable modem does not appear to interfere significantly with FAST's ability to set the congestion window size to its target. However, the cable modem does appear to introduce consistent additional delays when the link is highly, but not fully, utilised. These unexplained delays mean that a larger congestion window is required, and must be taken into account when setting FAST's parameters, notably the target queue size, alpha

QNA inverse model for capacity provisioning in delay constrained IP networks

This technical report is an extended version of a paper, which addresses the problem of dimensioning links in a multiservice IP network subject to satisfying varying performance requirements for different traffic classes. These performance requirements are viewed in terms of mean end-to-end delays required for the various traffic classes or in terms of random variations of their delays (i.e., jitter) or a combination of both. In this report we provide a detailed presentation and analysis of the recursive methods for inversion of the well-known QNA performance models, which [the previous paper] employs. Also, the accuracy of the model is investigated by means of a simulation study over an extended range of test cases. The results demonstate the capability of the model in guaranteeing the end-to-end delay requirements for the traffic classes

Experimental evaluation of FAST TCP performance and fairness in DOCSIS cable modem networks

In this paper we present experimental results evaluating the performance and fairness of FAST TCP in a series of tests involving realistic low rate network access scenarios. Links both using the DOCSIS cable modem medium access control (MAC) cable modem and simple low rate links were investigated. We seek to compare our expectations from theory with the behavior of an actual access network implementation

Implementing a testbed for the evaluation of FAST TCP in DOCSIS-based access networks

This technical report describes the process of implementing a testbed, which was used in [1] to experimentally evaluate the performance of FAST under typical ‘edge of network’ scenarios involving DOCSIS (Data Over Cable Service Interface Specification) cable system

Efficient capacity provisioning in delay constrained IP networks

This paper addresses the problem of capacity provisioning in a QoS enabled IP network, subject to satisfying varying performance requirements for different traffic classes. These performance requirements are viewed in terms of mean end-to-end delays required for the various traffic classes or in terms of random variations of their delays (i.e., jitter) or a combination of both. The accuracy of the model is investigated by means of a simulation study over an extended range of test cases for different traffic load characteristics and traffic intensities at the nodes. The results demonstrate the capability of the model in guaranteeing the end-to-end delay requirements for the traffic classes

Design of IP networks with end-to-end performance guarantees

In this paper, we examine the issues that surround IP network design with quality of service (QoS) guarantees and propose a new network design methodology. The proposed network design model takes account of the new QoS technologies (i.e., DiffServ/MPLS) and allows for multiple delay constraints so that guaranteed performance can be achieved for each of the traffic classes. After discussing the most crucial planning issues that must be addressed when QoS mechanisms are used in an IP-based network, a non-linear multicommodity optimisation problem is formulated and heuristics for its approximate solutions are described. The network design model is evaluated in terms of accuracy and scalability for each of the main components that the model employs. The computational results for each of the building blocks demonstrate that realistic size problems can be solved with the proposed method