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End-to-End Congestion Control for System Area Networks
Santos, Jose Renato; Turner, Yoshio; Janakiraman, G. (John)
Keyword(s): congestion control; system area networks; SAN; InfiniBand; window control; rate control; ECN; I/O Interconnect
Abstract: System Area Networks (SANs) using link-level flow control experience congestion spreading, where one bottleneck link causes traffic to block throughout the network. In this paper, an end-to-end congestion control scheme is proposed that avoids congestion spreading, delivers high throughput, and prevents flow starvation. It couples a simple switch-based ECN packet marking mechanism appropriate for typical SAN switches with small input buffers, together with hybrid window and rate control at end-devices. The classic fairness convergence requirement for source response functions assumes network feedback is synchronous. We relax the classic requirement by exploiting the asynchronous behavior of packet marking. Our experimental results demonstrate that compared to conventional approaches, our proposed marking mechanism improves fairness. Moreover, rate increase functions possible under the relaxed requirement reclaim available bandwidth aggressively and improve throughput in both static and dynamic traffic scenarios.
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