International Symposium on Performance Evaluation of Computer and Telecommunication Systems, Jun 16, 2008
Interest continues to grow in alternative transport protocols to the Transmission Control Protoco... more Interest continues to grow in alternative transport protocols to the Transmission Control Protocol (TCP). These alternatives include protocols designed to give greater efficiency in high-speed, high-delay environments (so-called high-speed TCP variants), and protocols that provide congestion control without reliability. For the former category, along with the deployed base of 'vanilla' TCP -TCP NewReno -the TCP variants BIC and Cubic are widely used within Linux: for the latter category, the Datagram Congestion Control Protocol (DCCP) is currently on the IETF Standards Track. It is clear that future traffic patterns will consist of a mix of flows from these protocols (and others). So, it is important for users and network operators to be aware of the impact that these protocols may have on users. We assess the performance of DCCP CCID2 relative to TCP NewReno, and variants BIC and CUBIC, all in "out-of-the box" configurations. We use a testbed and end-to-end measurements to assess overall throughput, and also to assess fairness -how well these protocols might respond to each other when operating over the same endto-end network path. We find that DCCP CCID2 shows good fairness with NewReno under our test conditions, while BIC and CUBIC show unfairness above round-trip times of 25ms.
Interest continues to grow in alternative transport protocols to the Transmission Control Protoco... more Interest continues to grow in alternative transport protocols to the Transmission Control Protocol (TCP). These alternatives include protocols designed to give greater efficiency in high-speed, high-delay environments (so-called high-speed TCP variants), and protocols that provide congestion control without reliability. For the former category, along with the deployed base of 'vanilla' TCP -TCP NewReno -the TCP variants BIC and CUBIC are widely used within Linux: for the latter category, the Datagram Congestion Control Protocol (DCCP) is currently on the IETF Standards Track. It is clear that future traffic patterns will consist of a mix of flows from these protocols (and others). So, it is important for users and network operators to be aware of the impact that these protocols may have on users. We show the measurement of fairness in throughput performance of DCCP Congestion Control ID 2 (CCID2) relative to TCP NewReno, and variants Binary Increase Congestion control (BIC), CUBIC and Compound, all in "out-of-the box" configurations. We use a testbed and endto-end measurements to assess overall throughput, and also to assess fairness -how well these protocols might respond to each other when operating over the same end-to-end network path. We find that, in our testbed, DCCP CCID2 shows good fairness with NewReno, while BIC, CUBIC and Compound show unfairness above round-trip times of 25ms.
A comparative performance evaluation of dccp Performance Evaluation of Computer and Telecommunication Systems
Interest continues to grow in alternative transport protocols to the Transmission Control Protoco... more Interest continues to grow in alternative transport protocols to the Transmission Control Protocol (TCP). These alternatives include protocols designed to give greater efficiency in high-speed, high-delay environments (so-called high-speed TCP variants), and protocols that provide congestion control without reliability. For the former category, along with the deployed base of dasiavanillapsila TCP - TCP NewReno - the TCP variants BIC and Cubic are widely used within Linux: for the latter category, the Datagram Congestion Control Protocol (DCCP) is currently on the IETF Standards Track. It is clear that future traffic patterns will consist of a mix of flows from these protocols (and others). So, it is important for users and network operators to be aware of the impact that these protocols may have on users. We assess the performance of DCCP CCID2 relative to TCP NewReno, and variants BIC and CUBIC, all in ldquoout-of-the boxrdquo configurations. We use a testbed and end-to-end measur...
2011 IEEE International Conference on Advanced Information Networking and Applications, 2011
One of the operational goals of a middleware platform is to provide a mechanism of distributing c... more One of the operational goals of a middleware platform is to provide a mechanism of distributing computation requests in a way that hides from the programmer the complexity of the underlying systems platform. This means that distribution mechanisms used to harness a set of computer and network resources should not expose to the programmer the detailed systems aspects which are unrelated to their application. Ideally, the programmer should be left to concentrate on the functionality of his/her application without having to be concerned with how the distribution is achieved or how the resources are used. However, this is not true today: programmers need to be aware of details of the middleware in use and are constrained by it in the design of their application, e.g. API constraints. We present a proof-of-concept demonstration of a middleware platform that imposes absolutely no constraints on the programmer apart form those used in the programming language itself. We demonstrate the efficacy of our approach with a prototype implementation in Java, running on a cluster of 20 nodes with a performance comparison with XML-RPC and Java-RMI.
2009 International Conference on Advanced Information Networking and Applications, 2009
Keeping router buffering low helps minimise delay (as well as keeping router costs low), whilst i... more Keeping router buffering low helps minimise delay (as well as keeping router costs low), whilst increasing buffering minimises loss. This is a trade-off for which there is no single 'correct' solution. In order to maintain effective throughput for TCP, whilst minimising router buffer requirements, current results suggest that different amounts of buffering are needed depending on the position in the network (e.g., edge or core), and on the relative capacity of ingress and egress links to a router. However, today we have several different variants of TCP in use, and each is designed to have different behaviour especially on paths with high bandwidth-delay product (BDP) values. We use a testbed to investigate the effects of different amounts of 'onpath' buffering (OPB) on the performance of four TCP variants -TCP NewReno, BIC, CUBIC, and Compound TCPover various end-to-end round-trip-times (RTTs). Specifically, we consider how the variants respond when competing for bandwidth on a bottleneck link. We find that overall performance depends on both the RTT and the OPB provision, and that the observed behaviour is not consistent across the range of RTT and OPB values.
2010 24th IEEE International Conference on Advanced Information Networking and Applications, 2010
New transport protocols continue to appear as alternatives to the Transmission Control Protocol (... more New transport protocols continue to appear as alternatives to the Transmission Control Protocol (TCP). Many of these are are designed to address TCP's inefficiency in operating over paths with a high bandwidth-delay product (BDP). To test these new protocols, especially comparatively, and to understand their interactions, extensions to the ns2 simulator allow real code from the linux kernel to be used within the ns2 simulations. However, how does the performance of such configurations compare to test-bed experiments of the same configuration? Although, anecdotally, there are often comments within the research community about such issues, there are no studies that quantify the differences for a specific protocol suite. Using a simple testbed, we assess four different transport protocols in a comparative study to examine how well ns2 matches reality. Our tests are all conducted at 100Mb/s over a wide range of delay and router buffer conditions: end-to-end delays from 25ms to 400ms, with end-to-end path buffering of 20% to 100% of the BDP. We find that in our simple configuration, there are significant differences in performance between ns2 and the testbed.
2008 4th Ieee International Conference on Wireless and Mobile Computing, Networking and Communications (Wimob), 2008
Mobile, delay-tolerant, ad hoc and pocket-switched networks may form an important part of future ... more Mobile, delay-tolerant, ad hoc and pocket-switched networks may form an important part of future ubiquitous computing environments. Understanding how to efficiently and effectively route information through such networks is an important research challenge, and much recent work has looked at detecting communities and cliques to determine forwarding paths. Such detected communities, however, may miss important aspects. For instance, a user may have strong social ties to another user that they seldom encounter; a detected social network may omit this tie and so produce sub-optimal forwarding paths. Moreover, the delay in detecting communities may slow the bootstrapping of a new delay-tolerant network. This paper explores the use of self-reported social networks for routing in mobile networks in comparison with detected social networks discovered through encounters. Using encounter records from a group of participants carrying sensor motes, we generate detected social networks from these records. We use these networks for routing, and compare these to the social networks which the users have self-reported on a popular social networking website. Using techniques from social network analysis, we find that the two social networks are different. These differences, however, do not lead to a significant impact on delivery ratio, while the self-reported social network leads to a significantly lower cost.
22nd International Conference on Advanced Information Networking and Applications (aina 2008), 2008
We present experimental results evaluating fairness of several proposals to change the TCP conges... more We present experimental results evaluating fairness of several proposals to change the TCP congestion control algorithm, in support of operation on high bandwidth-delayproduct (BDP) network paths. We examine and compare the fairness of New Reno TCP, BIC, Cubic, Hamilton-TCP, Highspeed-TCP and Scalable-TCP. We focus on four different views of fairness: TCP-friendliness, RTT-fairness, intraand inter-protocol fairness.
AbstractInterest continues to grow in alternative transport protocols to the Transmission Contro... more AbstractInterest continues to grow in alternative transport protocols to the Transmission Control Protocol (TCP). These alternatives include protocols designed to give greater efficiency in high-speed, high-delay environments (so-called high-speed TCP variants), and protocols ...
2008 5th International Conference on Broadband Communications, Networks and Systems, 2008
Many new transport protocols are being defined, including, for example, variants of the Transmiss... more Many new transport protocols are being defined, including, for example, variants of the Transmission Control Protocol (TCP), to better match the requirements of new applications. A key issue in the evaluation of protocol flows, in terms of their performance, is how fair they are to other flows. Specifically, it is important to understand how a mix of existing and/or new protocols will interact with each other when using the same network resources. Such observations help to inform protocol design, and allow an assessment of potential impacts on users. We present a simple, yet effective, methodology for examining a specific case of inter-flow fairness based solely on measurements of flow performance. As well as using an existing fairness metric, we propose a new metric which provides a richer information summary for the evaluation of fairness.
There is a growing interest in the use of variants of the Transmission Control Protocol (TCP) in ... more There is a growing interest in the use of variants of the Transmission Control Protocol (TCP) in high-speed networks. ns-2 has implementations of many of these high-speed TCP variants, as does Linux. ns-2, through an extension, permits the incorporation of Linux TCP code within ns-2 simulations. As these TCP variants become more widely used, users are concerned about how these different variants of TCP might interact in a real network environment-how fair are these protocol variants to each other (in their use of the available capacity) when sharing the same network. Typically, the answer to this question might be sought through simulation and/or by use of an experimental testbed. So, we compare with TCP NewReno the fairness of the congestion control algorithms for 5 high-speed TCP variants-BIC, Cubic, Scalable, High-Speed and Hamilton-on both ns-2 and on an experimental testbed running Linux. In both cases, we use the same TCP code from Linux. We observe some differences between the behaviour of these TCP variants when comparing the testbed results to the results from ns-2, but also note that there is generally good agreement.
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Papers by Martin Bateman