To Coordinate Or Not To Coordinate? Wide-Area Traffic Management for Data Centers
Report ID: TR-998-15Author: Chiang, Mung / Rexford, Jennifer / Jiang, Joe Wenjie / Narayana, Srinivas
Date: 2012-12-30
Pages: 19
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Abstract:
In this paper, we study the impact of coordinating the selection of data centers for clients (“mapping”) and performing multi-homed network-routing (“routing”) from data centers, two decisions which are conventionally managed independently. We model their functional separation and degrees of coordination through an optimization framework, and study the impact of coordination on (i) service performance, (ii) robustness to traffic variability, and (iii) bandwidth costs. We show that in theory, performing mapping and routing independently can lead to much lower performance or higher costs than a coordinated decision. In practice, our tracebased evaluations on an operational CDN show that coarsegrained information-sharing between mapping and routing is sufficient for near-optimal request latencies, but not minimal costs. Further, even complete information-sharing between mapping and routing is not sufficiently robust to traffic variability, as ISP-links can easily be overwhelmed due to traffic burstiness. To address this issue, we design a coordination technique which is much more robust to traffic variability, and is also provably optimal.