| Controlling bandwidth in cloud-based computing approaches
The UCSD algorithm enables distributed rate limiters to work together to enforce global bandwidth rate limits, and dynamically shift bandwidth allocations across multiple sites or networks, according to current network demand. Barath Raghavan, a computer science Ph.D. candidate at UCSD's Jacobs School of Engineering looked to computing clouds and, together with his co-authors, developed a new way to manage bandwidth. “With our system, an organization with mirrored websites or other services across the globe could dynamically shift its bandwidth allocations between sites based on demand. You can’t do that now, and this lack of control is a significant drawback to today’s cloud-based computing approaches,” said Barath Raghavan, the first author on a new paper describing the work, and a Ph.D. candidate in the Department of Computer Science and Engineering at UCSD’s Jacobs School of Engineering. The ‘flow proportional share’ algorithm the UCSD computer scientists created enables the coordinated policing of a cloud-based service’s network traffic, and therefore, the cost associated with this traffic. The TCP-centric design is scalable to hundreds of nodes, runs with very low overhead, and is robust to both loss and communication delay, making it practical for deployment in nationwide service providers, the authors write. Distributed rate limiting could be useful in a variety of ways: * Cloud-based resource providers could control the use of network bandwidth, and associated costs, as if all the bandwidth were sourced from a single pipe. * For content-distribution networks that currently provide replication services to third-party Web sites, distributed rate limiting could provide a powerful tool for managing access to client content. * Internet testbeds such as Planetlab are often overrun with network demands from users. Distributed rate limiting could bring the bandwidth crisis under control and render such research tools much more effective. Going with the (TCP) flow A gossip protocol communicates these demand values among all the associated rate limiters. Next, the new algorithm ranks the rate limiters according to network traffic demands and splits the bandwidth accordingly. “Our algorithm allows individual flows to compete dynamically for bandwidth not only with flows traversing the same limiter, but with flows traversing other limiters as well,” Raghavan explained. The UCSD computer scientists performed extensive evaluations of their system, using Jain’s fairness index as a metric of inter-flow fairness. In a wide variety of Internet traffic patterns, the authors demonstrated that their approach to distributed limiting of the rate of bandwidth usage works as well as a single rate limiter would work, with very little overhead. Paper citation: Funders: National Science Foundation (NSF)
•Date: 31st Aug 2007• Region: US/World •Type: Article •Topic: IT continuity
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