Adrian Sai-Wah Tam

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In a data center network, for example, it is quite often to use controllers to manage resources in a centralized manner. Centralized control, however, imposes a scalability problem. In this paper, we investigate the use of multiple independent controllers instead of a single omniscient controller to manage resources. Each controller looks after a portion of(More)
Incast applications have grown in popularity with the advancement of data center technology. It is found that the TCP incast may suffer from the throughput collapse problem, as a consequence of TCP retransmission timeouts when the bottleneck buffer is overwhelmed and causes the packet losses. This is critical to the Quality of Service of cloud computing(More)
In best-effort networks, fairness has been used as a criterion to guide the design of traffic controls. The notion of fairness has evolved over time, from simple equality to a form of equality modulated by the user’s need (e.g. max-min and proportional fairness). However, fairness has always been defined on a per-user basis for a deterministic workload. In(More)
Admission control has been shown to be a preferred alternative to TCP-friendly congestion control for inelastic flows in heterogeneous networks shared by elastic and inelastic traffic. However, it is possible for an inelastic flow to adopt different level of aggressiveness in implementing the admission control. How these different levels of aggressiveness(More)
An in vitro model was used to determine the influence of tear depth on the propagation pressure of aortic dissections. Saline was injected into the media of segments of 20 porcine thoracic aortas to create blebs. A circumferential slit was made on the intimal side of each bleb, connecting the true lumen to the false lumen. Each aorta was then pressurized(More)
Many applications (e.g., cluster based storage and MapReduce) in modern data centers require a high fan-in, many-to-one type of data communication (known as TCP incast), which could cause severe incast congestion in switches and result in TCP goodput collapse, substantially degrading the application performance. The root cause of such a collapse is the long(More)
We propose a fast reroute scheme for the single link failure protection of IP multicast network. A multicast network connects nodes as a spanning tree, which is vulnerable to link failures. Our scheme uses ring topologies to ensure a backup path always exists to any single link failure and only a few nodes in the neighborhood of the failed link have to(More)
The recent literature on data center networks often propose the use of centralized control server to manage resources or for coordination. These controllers are always a single omniscient device. While we see no problems in practice yet as it works for small scale networks, there is a scalability concern. This paper proposes the idea of devolved(More)
Data center networks (DCNs) usually have a regular topology providing high bandwidth and low latency with multi-paths. In a data-intensive application on DCNs, it is important to be able to use all the available bandwidth. However, this is not easy to achieve because of the locality of congestion information. In this paper, we propose a reactive reroute(More)