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Nikhil Handigol

Bio: Nikhil Handigol is an academic researcher from Stanford University. The author has contributed to research in topics: Routing protocol & Wireless network. The author has an hindex of 11, co-authored 14 publications receiving 2689 citations. Previous affiliations of Nikhil Handigol include Indian Institute of Technology Madras.

Papers
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Proceedings ArticleDOI
10 Dec 2012
TL;DR: This paper puts CBE to the test, using the prototype, Mininet-HiFi, to reproduce key results from published network experiments such as DCTCP, Hedera, and router buffer sizing and suggests that CBE makes research results easier to reproduce and build upon.
Abstract: In an ideal world, all research papers would be runnable: simply click to replicate all results, using the same setup as the authors. One approach to enable runnable network systems papers is Container-Based Emulation (CBE), where an environment of virtual hosts, switches, and links runs on a modern multicore server, using real application and kernel code with software-emulated network elements. CBE combines many of the best features of software simulators and hardware testbeds, but its performance fidelity is unproven.In this paper, we put CBE to the test, using our prototype, Mininet-HiFi, to reproduce key results from published network experiments such as DCTCP, Hedera, and router buffer sizing. We report lessons learned from a graduate networking class at Stanford, where 37 students used our platform to replicate 18 published results of their own choosing. Our experiences suggest that CBE makes research results easier to reproduce and build upon.

507 citations

Proceedings ArticleDOI
14 Nov 2012
TL;DR: This work measures three popular video streaming services -- Hulu, Netflix, and Vudu -- and finds that accurate client-side bandwidth estimation above the HTTP layer is hard, and rate selection based on inaccurate estimates can trigger a feedback loop, leading to undesirably variable and low-quality video.
Abstract: Today's commercial video streaming services use dynamic rate selection to provide a high-quality user experience. Most services host content on standard HTTP servers in CDNs, so rate selection must occur at the client. We measure three popular video streaming services -- Hulu, Netflix, and Vudu -- and find that accurate client-side bandwidth estimation above the HTTP layer is hard. As a result, rate selection based on inaccurate estimates can trigger a feedback loop, leading to undesirably variable and low-quality video. We call this phenomenon the "downward spiral effect", and we measure it on all three services, present insights into its root causes, and validate initial solutions to prevent it.

372 citations

Proceedings ArticleDOI
13 Aug 2012
TL;DR: The state exchange points in a distributed SDN control plane are characterized and two key state distribution trade-offs are identified and simulated in the context of an existing SDN load balancer application.
Abstract: Software Defined Networks (SDN) give network designers freedom to refactor the network control plane. One core benefit of SDN is that it enables the network control logic to be designed and operated on a global network view, as though it were a centralized application, rather than a distributed system - logically centralized. Regardless of this abstraction, control plane state and logic must inevitably be physically distributed to achieve responsiveness, reliability, and scalability goals. Consequently, we ask: "How does distributed SDN state impact the performance of a logically centralized control application?"Motivated by this question, we characterize the state exchange points in a distributed SDN control plane and identify two key state distribution trade-offs. We simulate these exchange points in the context of an existing SDN load balancer application. We evaluate the impact of inconsistent global network view on load balancer performance and compare different state management approaches. Our results suggest that SDN control state inconsistency significantly degrades performance of logically centralized control applications agnostic to the underlying state distribution.

344 citations

Journal ArticleDOI
07 Jan 2010
TL;DR: FlowVisor is demonstrated, a special purpose OpenFlow controller that allows multiple researchers to run experiments safely and independently on the same production OpenFlow network and four network slices running in parallel.
Abstract: 1 SLICED PROGRAMMABLE NETWORKS OpenFlow [4] has been demonstrated as a way for researchers to run networking experiments in their production network Last year, we demonstrated how an OpenFlow controller running on NOX [3] could move VMs seamlessly around an OpenFlow network [1] While OpenFlow has potential [2] to open control of the network, only one researcher can innovate on the network at a time What is required is a way to divide, or slice, network resources so that researchers and network administrators can use them in parallel Network slicing implies that actions in one slice do not negatively affect other slices, even if they share the same underlying physical hardware A common network slicing technique is VLANs With VLANs, the administrator partitions the network by switch port and all traffic is mapped to a VLAN by input port or explicit tag This coarse-grained type of network slicing complicates more interesting experiments such as IP mobility or wireless handover Here, we demonstrate FlowVisor, a special purpose OpenFlow controller that allows multiple researchers to run experiments safely and independently on the same production OpenFlow network To motivate FlowVisor’s flexibility, we demonstrate four network slices running in parallel: one slice for the production network and three slices running experimental code (Figure 1) Our demonstration runs on real network hardware deployed on our production network at Stanford and a wide-area test-bed with a mix of wired and wireless technologies

319 citations

Proceedings ArticleDOI
02 Apr 2014
TL;DR: This paper built NetSight, an extensible platform that captures packet histories and enables applications to concisely and flexibly retrieve packet histories of interest and built four applications that illustrate its flexibility: an interactive network debugger, a live invariant monitor, a path-aware history logger, and a hierarchical network profiler.
Abstract: The complexity of networks has outpaced our tools to debug them; today, administrators use manual tools to diagnose problems In this paper, we show how packet histories--the full stories of every packet's journey through the network--can simplify network diagnosis To demonstrate the usefulness of packet histories and the practical feasibility of constructing them, we built NetSight, an extensible platform that captures packet histories and enables applications to concisely and flexibly retrieve packet histories of interest Atop NetSight, we built four applications that illustrate its flexibility: an interactive network debugger, a live invariant monitor, a path-aware history logger, and a hierarchical network profiler On a single modern multi-core server, NetSight can process packet histories for the traffic of multiple 10 Gb/s links For larger networks, NetSight scales linearly with additional servers and scales even further with straightforward additions to hardware- and hypervisor-based switches

309 citations


Cited by
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Journal ArticleDOI
01 Jan 2015
TL;DR: This paper presents an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications, and presents the key building blocks of an SDN infrastructure using a bottom-up, layered approach.
Abstract: The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

3,589 citations

Journal ArticleDOI
TL;DR: The SDN architecture and the OpenFlow standard in particular are presented, current alternatives for implementation and testing of SDN-based protocols and services are discussed, current and future SDN applications are examined, and promising research directions based on the SDN paradigm are explored.
Abstract: The idea of programmable networks has recently re-gained considerable momentum due to the emergence of the Software-Defined Networking (SDN) paradigm. SDN, often referred to as a ''radical new idea in networking'', promises to dramatically simplify network management and enable innovation through network programmability. This paper surveys the state-of-the-art in programmable networks with an emphasis on SDN. We provide a historic perspective of programmable networks from early ideas to recent developments. Then we present the SDN architecture and the OpenFlow standard in particular, discuss current alternatives for implementation and testing of SDN-based protocols and services, examine current and future SDN applications, and explore promising research directions based on the SDN paradigm.

2,013 citations

Posted Content
TL;DR: Software-Defined Networking (SDN) as discussed by the authors is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network.
Abstract: Software-Defined Networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound APIs, network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms -- with a focus on aspects such as resiliency, scalability, performance, security and dependability -- as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

1,968 citations

Proceedings ArticleDOI
20 Oct 2010
TL;DR: The greatest value of Mininet will be supporting collaborative network research, by enabling self-contained SDN prototypes which anyone with a PC can download, run, evaluate, explore, tweak, and build upon.
Abstract: Mininet is a system for rapidly prototyping large networks on the constrained resources of a single laptop The lightweight approach of using OS-level virtualization features, including processes and network namespaces, allows it to scale to hundreds of nodes Experiences with our initial implementation suggest that the ability to run, poke, and debug in real time represents a qualitative change in workflow We share supporting case studies culled from over 100 users, at 18 institutions, who have developed Software-Defined Networks (SDN) Ultimately, we think the greatest value of Mininet will be supporting collaborative network research, by enabling self-contained SDN prototypes which anyone with a PC can download, run, evaluate, explore, tweak, and build upon

1,890 citations