Cross-layer flow and congestion control for datacenter networks
Proceedings of the 3rd Workshop on Data Center - Converged and Virtual Ethernet Switching
Arbitration of many thousand flows at 100G and beyond
Proceedings of the 2013 Interconnection Network Architecture: On-Chip, Multi-Chip
How elastic is your virtualized datacenter fabric?
Proceedings of the 2013 Interconnection Network Architecture: On-Chip, Multi-Chip
Proceedings of the ACM SIGCOMM 2013 conference on SIGCOMM
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One of the consequential new features of emerging datacenter networks is lossless ness, achieved by means of Priority Flow Control (PFC). Despite PFC's key role in the datacenter and its increasing availability--supported by virtually all Converged Enhanced Ethernet (CEE) products--its impact remains largely unknown. This has motivated us to evaluate the sensitivity of three widespread TCP versions to PFC, as well as to the more involved Quantized Congestion Notification (QCN) congestion management mechanism. As datacenter workloads we have adopted several representative commercial and scientific applications. For evaluation we employ an accurate Layer 2 CEE network simulator coupled with a TCP implementation extracted from FreeBSD v9. A somewhat unexpected outcome of this investigation is that PFC significantly improves TCP performance across all tested configurations and workloads, hence our recommendation to enable PFC whenever possible. In contrast, QCN can help or harm depending on its parameter settings, which are currently neither adaptive nor universal for datacenters. To the best of our knowledge this is the first performance evaluation of TCP performance in lossless CEE networks.