Static virtual channel allocation in oblivious routing

Most virtual channel routers have multiple virtual channels to mitigate the effects of head-of-line blocking. When there are more flows than virtual channels at a link, packets or flows must compete for channels, either in a dynamic way at each link or by static assignment computed before transmission starts. In this paper, we present methods that statically allocate channels to flows at each link when oblivious routing is used, and ensure deadlock freedom for arbitrary minimal routes when two or more virtual channels are available. We then experimentally explore the performance trade-offs of static and dynamic virtual channel allocation for various oblivious routing methods, including DOR, ROMM, Valiant and a novel bandwidth-sensitive oblivious routing scheme (BSORM). Through judicious separation of flows, static allocation schemes often exceed the performance of dynamic allocation schemes

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

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

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

Heuristic algorithms for wireless mesh network planning

x, 131 leaves : ill. ; 29 cmTechnologies like IEEE 802.16j wireless mesh networks are drawing increasing attention of the research community. Mesh networks are economically viable and may extend services such as Internet to remote locations. This thesis takes interest into a planning problem in IEEE 802.16j networks, where we need to establish minimum cost relay and base stations to cover the bandwidth demand of wireless clients. A special feature of this planning problem is that any node in this network can send data to at most one node towards the next hop, thus traffic flow is unsplittable from source to destination. We study different integer programming formulations of the problem. We propose four types of heuristic algorithms that uses greedy, local search, variable neighborhood search and Lagrangian relaxation based approaches for the problem. We evaluate the algorithms on database of network instances of 500-5000 nodes, some of which are randomly generated network instances, while other network instances are generated over geometric distribution. Our experiments show that the proposed algorithms produce satisfactory result compared to benchmarks produced by generalized optimization problem solver software