33 research outputs found
Application-Aware Deadlock-Free Oblivious Routing
Conventional oblivious routing algorithms are either not application-aware or assume that each flow has its own private channel to ensure deadlock avoidance. We present a framework for application-aware routing that assures deadlock-freedom under one or more channels by forcing routes to conform to an acyclic channel dependence graph. Arbitrary minimal routes can be made deadlock-free through appropriate static channel allocation when two or more channels are available. Given bandwidth estimates for flows, we present a mixed integer-linear programming (MILP) approach and a heuristic approach for producing deadlock-free routes that minimize maximum channel load. The heuristic algorithm is calibrated using the MILP algorithm and evaluated on a number of benchmarks through detailed network simulation. Our framework can be used to produce application-aware routes that target the minimization of latency, number of flows through a link, bandwidth, or any combination thereof
Application-Aware Deadlock-Free Oblivious Routing
Conventional oblivious routing algorithms are either not application-aware or assume that each flow has its own private channel to ensure deadlock avoidance. We present a framework for application-aware routing that assures deadlock-freedom under one or more channels by forcing routes to conform to an acyclic channel dependence graph. Arbitrary minimal routes can be made deadlock-free through appropriate static channel allocation when two or more channels are available. Given bandwidth estimates for flows, we present a mixed integer-linear programming (MILP) approach and a heuristic approach for producing deadlock-free routes that minimize maximum channel load. The heuristic algorithm is calibrated using the MILP algorithm and evaluated on a number of benchmarks through detailed network simulation. Our framework can be used to produce application-aware routes that target the minimization of latency, number of flows through a link, bandwidth, or any combination thereof
Department of Computer Science Activity 1998-2004
This report summarizes much of the research and teaching activity of the Department of Computer Science at Dartmouth College between late 1998 and late 2004. The material for this report was collected as part of the final report for NSF Institutional Infrastructure award EIA-9802068, which funded equipment and technical staff during that six-year period. This equipment and staff supported essentially all of the department\u27s research activity during that period
Diastolic arrays : throughput-driven reconfigurable computing
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (leaves 67-70).In this thesis, we propose a new reconfigurable computer substrate: diastolic arrays. Diastolic arrays are arrays of processing elements that communicate exclusively through First-In First-Out (FIFO) queues, and provide hardware support to guarantee bandwidth and buffer space for all data transfers. FIFO control implies that a module idles if its input FIFOs are empty, and stalls if its output FIFOs are full. The timing of data transfers between processing elements in diastolic arrays is therefore significantly more relaxed than in systolic arrays or pipelines. All specified data transfers are statically routed, and the routing problem to maximize average throughput can be optimally or near-optimally solved in polynomial time by formulating it as a maximum concurrent multicommodity flow problem and using linear programming. We show that the architecture of diastolic arrays enables efficient synthesis from high-level specifications of communicating finite state machines, providing a high-performance, off-the-shelf computer substrate that can be easily programmed.by Myong Hyon Cho.S.M
Bandwidth-sensitive oblivious routing
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Includes bibliographical references (p. 81-83).Traditional oblivious routing algorithms either do not take into account the bandwidth demand, or assume that each flow has its own private channel to guarantee deadlock freedom. Though adaptive routing schemes can react to varying network traffic, they require complicated router designs. In this thesis, we present a polynomial-time heuristic routing algorithm that takes bandwidth requirements of each flow into account to minimize maximum channel load. The heuristic algorithm has two variants. The first one produces a deadlock-free route. The second one produces a minimal route, and is deadlock-free with two or more virtual channels assuming proper VC allocation. Both routing algorithms are oblivious, and need only simple router designs. The performance of each bandwidth-sensitive routing algorithm is evaluated against dimension-order routing and against the other on a number of benchmarks.by Tina Wen.M.Eng
The Augmentation-Speed Tradeoff for Consistent Network Updates
Emerging software-defined networking technologies enable more adaptive
communication infrastructures, allowing for quick reactions to changes in
networking requirements by exploiting the workload's temporal structure.
However, operating networks adaptively is algorithmically challenging, as
meeting networks' stringent dependability requirements relies on maintaining
basic consistency and performance properties, such as loop freedom and
congestion minimization, even during the update process. This paper leverages
an augmentation-speed tradeoff to significantly speed up consistent network
updates. We show that allowing for a small and short (hence practically
tolerable, e.g., using buffering) oversubscription of links allows us to solve
many network update instances much faster, as well as to reduce computational
complexities (i.e., the running times of the algorithms). We first explore this
tradeoff formally, revealing the computational complexity of scheduling
updates. We then present and analyze algorithms that maintain logical and
performance properties during the update. Using an extensive simulation study,
we find that the tradeoff is even more favorable in practice than our
analytical bounds suggest. In particular, we find that by allowing just 10%
augmentation, update times reduce by more than 32% on average, across a
spectrum of real-world networks
Application-aware deadlock-free oblivious routing
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 67-71).Systems that can be integrated on a single silicon die have become larger and increasingly complex, and wire designs as communication mechanisms for these systems on chip (SoC) have shown to be a limiting factor in their performance. As an approach to remove the limitation of communication and to overcome wire delays, interconnection networks or Network-on-Chip (NoC) architectures have emerged. NoC architectures enable faster data communication between components and are more scalable. In designing NoC systems, there are three key issues; the topology, which directly depends on packaging technology and manufacturing costs, dictates the throughput and latency bounds of the network; the flit control protocol, which establishes how the network resources are allocated to packets exchanged between components; and finally, the routing algorithm, which aims at optimizing network performance for some topology and flow control protocol by selecting appropriate paths for those packets. Since the routing algorithm sits on top of the other layers of design, it is critical that routing is done in a matter that makes good usage of the resources of the network. Two main approaches to routing, oblivious and adaptive, have been followed in creating routing algorithms for these systems. Each approach has its pros and cons; oblivious routing, as opposite to adaptive routing, uses no network state information in determining routes at the cost of lower performance on certain applications, but has been widely used because of its simpler hardware requirements.(cont.) This thesis examines oblivious routing schemes for NoC architectures. It introduces various non-minimal, oblivious routing algorithms that globally allocate network bandwidth for a given application when estimated bandwidths for data transfers are provided, while ensuring deadlock freedom with no significant additional hardware. The work presents and evaluates these oblivious routing algorithms which attempt to minimize the maximum channel load (MCL) across all network links in an effort to maximize application throughput. Simulation results from popular synthetic benchmarks and concrete applications, such as an H.264 decoder, show that it is possible to achieve better performance than traditional deterministic and oblivious routing schemes.by Michel A. Kinsy.S.M
WizHaul: On the Centralization Degree of Cloud RAN Next Generation Fronthaul
Cloud Radio Access Network (C-RAN) will become a main building block for 5G. However, the stringent requirements of current fronthaul solutions hinder its large-scale deployment. In order to introduce C-RAN widely in 5G, the next generation fronthaul \agsrev{interface} (NGFI) will be based on a cost-efficient packet-based network with higher path diversity. In addition, NGFI shall support a flexible functional split of the RAN to adapt the amount of centralization to the capabilities of the transport network. In this paper we question the ability of standard techniques to route NGFI traffic while maximizing the centralization degree---the goal of C-RAN. We propose two solutions jointly addressing both challenges: (i) a nearly-optimal backtracking scheme, and (ii) a low-complex greedy approach. We first validate the feasibility of our approach in an experimental proof-of-concept, and then evaluate both algorithms via simulations in large-scale (real and synthetic) topologies. Our results show that state-of-the-art techniques fail at maximizing the centralization degree and that the achievable C-RAN centralization highly depends on the underlying topology structure.This work has received funding from the European Unions Horizon 2020 research and innovation programme under grant agreement No 671598 (5G-Crosshaul project) and 761536 (5G-Transformer project)
A Survey on Data Plane Programming with P4: Fundamentals, Advances, and Applied Research
With traditional networking, users can configure control plane protocols to
match the specific network configuration, but without the ability to
fundamentally change the underlying algorithms. With SDN, the users may provide
their own control plane, that can control network devices through their data
plane APIs. Programmable data planes allow users to define their own data plane
algorithms for network devices including appropriate data plane APIs which may
be leveraged by user-defined SDN control. Thus, programmable data planes and
SDN offer great flexibility for network customization, be it for specialized,
commercial appliances, e.g., in 5G or data center networks, or for rapid
prototyping in industrial and academic research. Programming
protocol-independent packet processors (P4) has emerged as the currently most
widespread abstraction, programming language, and concept for data plane
programming. It is developed and standardized by an open community and it is
supported by various software and hardware platforms. In this paper, we survey
the literature from 2015 to 2020 on data plane programming with P4. Our survey
covers 497 references of which 367 are scientific publications. We organize our
work into two parts. In the first part, we give an overview of data plane
programming models, the programming language, architectures, compilers,
targets, and data plane APIs. We also consider research efforts to advance P4
technology. In the second part, we analyze a large body of literature
considering P4-based applied research. We categorize 241 research papers into
different application domains, summarize their contributions, and extract
prototypes, target platforms, and source code availability.Comment: Submitted to IEEE Communications Surveys and Tutorials (COMS) on
2021-01-2