With the exponential growth of data centers, there is a need for re-thinking and re-designing networks to meet the demands of these large-scale operations. The concept of central control, once deemed ineffective in the Internet era, is gaining popularity in data centers due to their structured topologies and the ability to have a single entity in control of the entire network resources.

In this article, we focus on two specific problems related to central controller-assisted prioritization of interactive flow in data center networks. The first problem addressed is the scalability issue of Fastpass, a centralized “zero-queue” data center network. While Fastpass has proven to be an efficient solution, its central arbiter does not scale well beyond 256 nodes or 8 cores. To tackle this issue, the authors have re-designed the timeslot allocator of the central arbiter, resulting in linear scalability up to 12 cores and support for approximately 1024 nodes and 7.1 Terabits of network traffic. This enhancement enables Fastpass to handle larger data center networks without sacrificing performance.

The second problem investigated in this thesis is congestion control in a software-defined network (SDN). The authors propose a framework where the controller, equipped with a global view of the network, actively participates in congestion control decisions for end TCP hosts by appropriately setting the ECN bits of IPv4 packets. What makes this framework particularly appealing is its ease of deployment, requiring no modifications to the end node TCPs or SDN switches. The authors demonstrate significant performance improvements, reporting a 30x enhancement over TCP cubic and a 1.7x improvement over Random Early Detection (RED) in flow completion times for one implementation of this framework.

This research brings innovative solutions to the challenges faced by data center networks. By addressing issues such as scalability and congestion control, the authors have paved the way for more efficient and responsive data center networks. As data centers continue to grow in size and complexity, the insights and techniques presented in this thesis will undoubtedly play a crucial role in shaping the future of data center networking.

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