Buffer Sizing in the Internet: How can SDN help? (Spring 2013)

Research Project for “Topics in Internet Research” (Dr. Zartash Uzmi, Dr. Ihsan Ayyub- Spring 2013)
Collaborated with: Mahd Tauseef

Abstract: All routers in the Internet today contain buffers, to temporarily hold packets when the network congests. The size of these buffers governs network utilization, packet delays etc. playing an important role in the QoS a network achieves. As discussed recently by Appenzeller et al., most buffers today are ‘over-sized’ subject to an old rule-of-thumb which suggests that buffers must be equal to the Bandwidth-Delay product (BDP) i.e.( ¯RTT*C ) . Appenzeller et al. in [1] proposed a new rule that for a link with flows, a buffer size of (( ¯RTT*C ))⁄√n suffices. As centrally controlled Software Defined Networks (SDNs) emerge as the networks of tomorrow, one may wonder what gain they offer in sizing router buffers.
In this paper, we build upon the finding of [1] and explore quantitatively how a ‘dynamic buffer routing scheme’ based on an OpenFlow [2] switch compares with a conventional static buffer. We use MININET [3] for simulation, along with a POX controller [4] to show that dynamic buffer sizing promises better QoS by far. It not only achieves high utilization but guarantees low delay and low delay-variance independent of the number of flows in the link.

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