In data center applications, predictability in service time and controlled latency, especially tail latency, are essential for building performant applications. This is especially true for applications or services built by accessing data across thousands of servers to generate a user response. Current practice has been to run such services at low utilization to rein in latency outliers, which decreases efficiency and limits the number of service invocations developers can issue while still meeting tight latency budgets.In this paper, we analyze three data center applications, Memcached, OpenFlow, and Web search, to measure the effect of 1) kernel socket handling, NIC interaction, and the network stack, 2) application locks contested in the kernel, and 3) application-layer queueing due to requests being stalled behind straggler threads on tail latency. We propose Chronos, a framework to deliver predictable, low latency in data center applications. Chronos uses a combination of existing and new techniques to achieve this end, for example by supporting Memcached at 200,000 requests per second per server at mean latency of 10 μs with a 99 th percentile latency of only 30 μs, a factor of 20 lower than baseline Memcached.

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Solving "Big Data" problems requires bridging massive quantities of compute, memory, and storage, which requires a very high bandwidth network. Recently proposed direct connect networks like HyperX [1] and Flattened Butterfly [20] offer large capacity through paths of varying lengths between servers, and are highly cost effective for common data center workloads. However data center deployments are constrained to multi-rooted tree topologies like Fat-tree [2] and VL2 [16] due to shortest path routing and the limitations of commodity data center switch silicon.In this work we present Dahu 1 , simple enhancements to commodity Ethernet switches to support direct connect networks in data centers. Dahu avoids congestion hot-spots by dynamically spreading traffic uniformly across links, and forwarding traffic over non-minimal paths where possible. By performing load balancing primarily using local information, Dahu can act more quickly than centralized approaches, and responds to failure gracefully. Our evaluation shows that Dahu delivers up to 500% improvement in throughput over ECMP in large scale HyperX networks with over 130,000 servers, and up to 50% higher throughput in an 8,192 server Fat-tree network.

This paper presents the design and implementation of an incrementally scalable architecture for middleboxes based on commodity servers and operating systems. xOMB, the eXtensible Open MiddleBox, employs general programmable network processing pipelines, with user-defined C++ modules responsible for parsing, transforming, and forwarding network flows. We implement three processing pipelines in xOMB, demonstrating good performance for load balancing, protocol acceleration, and application integration. In particular, our xOMB load balancing switch is able to match or outperform a commercial programmable switch and popular open-source reverse proxy while still providing a more flexible programming model.

Mobile ad hoc networks inherently have very different properties from conventional networks. A mobile ad hoc network (MANET) is a collection of mobile nodes that are self configuring (network can be run solely by the operation of the end-users), capable of communicating with each other, establishing and maintaining connections as needed. Nodes in MANET are both routers and terminals. These networks are dynamic in the sense that each node is free to join and leave the network in a nondeterministic way. These networks do not have a clearly defined physical boundary, and therefore, have no specific entry or exit point. Although MANET is a very promising technology, challenges are slowing its development and deployment. Nodes in ad hoc networks are in general limited in battery power, CPU and capacity. Hence, the transmission ranges of these devices are also limited and nodes have to rely on the neighboring nodes in the network to route the packet to its destination node. Ad hoc networks are sometimes referred to as multi-hop networks, where a hop is a direct link between two nodes. MANET has many important applications, including battlefield operations, emergency rescues, mobile conferencing, home and community networking, sensor dust and so forth.