Less is More: Trading a Little Bandwidth for Ultra-Low Latency in the Data Center

Traditional measures of network goodness - goodput, quality of service, fairness - are expressed in terms of bandwidth. Network latency has rarely been a primary concern because delivering the highest level of bandwidth essentially entails driving up latency - at the mean and, especially, at the tail. Recently, however, there has been renewed interest in latency as a primary metric for mainstream applications. In this paper, the authors present the HULL (High-bandwidth Ultra-Low Latency) architecture to balance two seemingly contradictory goals: near baseline fabric latency and high bandwidth utilization. HULL leaves 'Bandwidth headroom' using Phantom Queues that deliver congestion signals before network links are fully utilized and queues form at switches.

Provided by: Stanford University Topic: Data Centers Date Added: Feb 2012 Format: PDF

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