Number of items: 3.
and Lee, Seungjoon
and Rabinovich, Michael
and Spatscheck, Oliver
and Van der Merwe, Jacobus Anycast-Aware Transport for Content Delivery Networks.
Anycast-based content delivery networks (CDNs) have many properties that make them ideal for the large scale distribution of content on the Internet. However, because routing changes can result in a change of the endpoint that terminates the TCP session, TCP session disruption remains a concern for anycast CDNs, especially for large ﬁle downloads. In this paper we demonstrate that this problem does not require any complex solutions. In particular, we present the design of a simple, yet efficient, mechanism to handle session disruptions due to endpoint changes. With our mechanism, a client can continue the download of the content from the point at which it was before the endpoint change. Furthermore, CDN servers purge the TCP connection state quickly to handle frequent switching with low system overhead. We demonstrate experimentally the effectiveness of our proposed mechanism and show that more complex mechanisms are not required. Speciﬁcally, we ﬁnd that our mechanism maintains high download throughput even with a reasonably high rate of endpoint switching, which is attractive for load balancing scenarios. Moreover, our results show that edge servers can purge TCP connection state after a single timeout-triggered retransmission without any tangible impact on ongoing connections. Besides improving server performance, this behavior improves the resiliency of the CDN to certain denial of service attacks.
and Gerber, Alexandre
and Hajiaghayi, Mohammad T.
and Pei, Dan
and Spatscheck, Oliver Network-Aware Forward Caching.
This paper proposes and evaluates a Network Aware Forward Caching approach for determining the optimal deployment strategy of forward caches to a network. A key advantage of this approach is that we can reduce the network costs associated with forward caching to maximize the beneﬁt obtained from their deployment. We show in our simulation that a 37% increase to net beneﬁts could be achieved over the standard method of full cache deployment to cache all POPs trafﬁc. In addition, we show that this maximal point occurs when only 68% of the total trafﬁc is cached. Another contribution of this paper is the analysis we use to motivate and evaluate this problem. We characterize the Internet trafﬁc of 100K subscribers of a US residential broadband provider. We use both layer 4 and layer 7 analysis to investigate the trafﬁc volumes of the ﬂows as well as study the general characteristics of the applications used. We show that HTTP is a dominant protocol and account for 68% of the total downstream trafﬁc and that 34% of that trafﬁc is multimedia. In addition, we show that multimedia content using HTTP exhibits a 83% annualized growth rate and other HTTP trafﬁc has a 53% growth rate versus the 26% over all annual growth rate of broadband trafﬁc. This shows that HTTP trafﬁc will become ever more dominent and increase the potential caching opportunities. Furthermore, we characterize the core backbone trafﬁc of this broadband provider to measure the distance travelled by content and trafﬁc. We ﬁnd that CDN trafﬁc is much more efﬁcient than P2P content and that there is large skew in the Air Miles between POP in a typical network. Our ﬁndings show that there are many opportunties in broadband provider networks to optimize how trafﬁc is delivered and cached.
and Wills, Craig Privacy Diffusion on the Web: A Longitudinal Perspective.
For the last few years we have studied the diffusion of private information about users as they visit various Web sites triggering data gathering aggregation by third parties. This paper reports on our longitudinal study consisting of multiple snapshots of our examination of such diffusion over four years. We examine the various technical ways by which third-party aggregators acquire data and the depth of userrelated information acquired. We study techniques for protecting against this privacy diffusion as well as limitations of such techniques. We introduce the concept of secondary privacy damage. Our results show increasing aggregation of user-related data by a steadily decreasing number of entities. A handful of companies are able to track users’ movement across almost all of the popular Web sites. Virtually all the protection techniques have signiﬁcant limitations highlighting the seriousness of the problem and the need for alternate solutions.
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