4,453 research outputs found
OutFlank Routing: Increasing Throughput in Toroidal Interconnection Networks
We present a new, deadlock-free, routing scheme for toroidal interconnection
networks, called OutFlank Routing (OFR). OFR is an adaptive strategy which
exploits non-minimal links, both in the source and in the destination nodes.
When minimal links are congested, OFR deroutes packets to carefully chosen
intermediate destinations, in order to obtain travel paths which are only an
additive constant longer than the shortest ones. Since routing performance is
very sensitive to changes in the traffic model or in the router parameters, an
accurate discrete-event simulator of the toroidal network has been developed to
empirically validate OFR, by comparing it against other relevant routing
strategies, over a range of typical real-world traffic patterns. On the
16x16x16 (4096 nodes) simulated network OFR exhibits improvements of the
maximum sustained throughput between 14% and 114%, with respect to Adaptive
Bubble Routing.Comment: 9 pages, 5 figures, to be presented at ICPADS 201
Deterministic Routing with HoL-Blocking-Awareness for Direct Topologies
AbstractRouting is a key design factor to obtain the maximum performance out of interconnection networks. Depending on the number of routing options that packets may use, routing algorithms are classified into two categories. If the packet can only use a single predetermined path, routing is deterministic, whereas if several paths are available, it is adaptive. It is well-known that adaptive routing usually outperforms deterministic routing. However, adaptive routers are more complex and introduces out-of-order delivery of packets. In this paper, we take up the challenge of developing a deterministic routing algorithm for direct topologies that can obtain a similar performance than adaptive routing, while providing the inherent advantages of deterministic routing such as in-order delivery of packets and implementation simplicity. The proposed deterministic routing algorithm is aware of the HoL-blocking effect, and it is designed to reduce it, which, as known, it is a key contributor to degrade interconnection network performance
Low-Memory Techniques for Routing and Fault-Tolerance on the Fat-Tree Topology
Actualmente, los clústeres de PCs están considerados como una alternativa eficiente a la hora de construir supercomputadores en los que miles de nodos de computación se conectan mediante una red de interconexión. La red de interconexión tiene que ser diseñada cuidadosamente, puesto que tiene una gran influencia sobre las prestaciones globales del sistema. Dos de los principales parámetros de diseño de las redes de interconexión son la topología y el encaminamiento. La topología define la interconexión de los elementos de la red entre sí, y entre éstos y los nodos de computación. Por su parte, el encaminamiento define los caminos que siguen los paquetes a través de la red.
Las prestaciones han sido tradicionalmente la principal métrica a la hora de evaluar las redes de interconexión. Sin embargo, hoy en día hay que considerar dos métricas adicionales: el coste y la tolerancia a fallos. Las redes de interconexión además de escalar en prestaciones también deben hacerlo en coste. Es decir, no sólo tienen que mantener su productividad conforme aumenta el tamaño de la red, sino que tienen que hacerlo sin incrementar sobremanera su coste. Por otra parte, conforme se incrementa el número de nodos en las máquinas de tipo clúster, la red de interconexión debe crecer en concordancia. Este incremento en el número de elementos de la red de interconexión aumenta la probabilidad de aparición de fallos, y por lo tanto, la tolerancia a fallos es prácticamente obligatoria para las redes de interconexión actuales.
Esta tesis se centra en la topología fat-tree, ya que es una de las topologías más comúnmente usadas en los clústeres. El objetivo de esta tesis es aprovechar sus características particulares para proporcionar tolerancia a fallos y un algoritmo de encaminamiento capaz de equilibrar la carga de la red proporcionando una buena solución de compromiso entre las prestaciones y el coste.Gómez Requena, C. (2010). Low-Memory Techniques for Routing and Fault-Tolerance on the Fat-Tree Topology [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8856Palanci
On the design of a high-performance adaptive router for CC-NUMA multiprocessors
Copyright © 2003 IEEEThis work presents the design and evaluation of an adaptive packet router aimed at supporting CC-NUMA traffic. We exploit a simple and efficient packet injection mechanism to avoid deadlock, which leads to a fully adaptive routing by employing only three virtual channels. In addition, we selectively use output buffers for implementing the most utilized virtual paths in order to reduce head-of-line blocking. The careful implementation of these features has resulted in a good trade off between network performance and hardware cost. The outcome of this research is a High-Performance Adaptive Router (HPAR), which adequately balances the needs of parallel applications: minimal network latency at low loads and high throughput at heavy loads. The paper includes an evaluation process in which HPAR is compared with other adaptive routers using FIFO input buffering, with or without additional virtual channels to reduce head-of-line blocking. This evaluation contemplates both the VLSI costs of each router and their performance under synthetic and real application workloads. To make the comparison fair, all the routers use the same efficient deadlock avoidance mechanism. In all the experiments, HPAR exhibited the best response among all the routers tested. The throughput gains ranged from 10 percent to 40 percent in respect to its most direct rival, which employs more hardware resources. Other results shown that HPAR achieves up to 83 percent of its theoretical maximum throughput under random traffic and up to 70 percent when running real applications. Moreover, the observed packet latencies were comparable to those exhibited by simpler routers. Therefore, HPAR can be considered as a suitable candidate to implement packet interchange in next generations of CC-NUMA multiprocessors.Valentín Puente, José-Ángel Gregorio, Ramón Beivide, and Cruz Iz
A survey of performance enhancement of transmission control protocol (TCP) in wireless ad hoc networks
This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Springer OpenTransmission control protocol (TCP), which provides reliable end-to-end data delivery, performs well in traditional wired network environments, while in wireless ad hoc networks, it does not perform well. Compared to wired networks, wireless ad hoc networks have some specific characteristics such as node mobility and a shared medium. Owing to these specific characteristics of wireless ad hoc networks, TCP faces particular problems with, for example, route failure, channel contention and high bit error rates. These factors are responsible for the performance degradation of TCP in wireless ad hoc networks. The research community has produced a wide range of proposals to improve the performance of TCP in wireless ad hoc networks. This article presents a survey of these proposals (approaches). A classification of TCP improvement proposals for wireless ad hoc networks is presented, which makes it easy to compare the proposals falling under the same category. Tables which summarize the approaches for quick overview are provided. Possible directions for further improvements in this area are suggested in the conclusions. The aim of the article is to enable the reader to quickly acquire an overview of the state of TCP in wireless ad hoc networks.This study is partly funded by Kohat University of Science & Technology (KUST),
Pakistan, and the Higher Education Commission, Pakistan
The Road Ahead for Networking: A Survey on ICN-IP Coexistence Solutions
In recent years, the current Internet has experienced an unexpected paradigm
shift in the usage model, which has pushed researchers towards the design of
the Information-Centric Networking (ICN) paradigm as a possible replacement of
the existing architecture. Even though both Academia and Industry have
investigated the feasibility and effectiveness of ICN, achieving the complete
replacement of the Internet Protocol (IP) is a challenging task.
Some research groups have already addressed the coexistence by designing
their own architectures, but none of those is the final solution to move
towards the future Internet considering the unaltered state of the networking.
To design such architecture, the research community needs now a comprehensive
overview of the existing solutions that have so far addressed the coexistence.
The purpose of this paper is to reach this goal by providing the first
comprehensive survey and classification of the coexistence architectures
according to their features (i.e., deployment approach, deployment scenarios,
addressed coexistence requirements and architecture or technology used) and
evaluation parameters (i.e., challenges emerging during the deployment and the
runtime behaviour of an architecture). We believe that this paper will finally
fill the gap required for moving towards the design of the final coexistence
architecture.Comment: 23 pages, 16 figures, 3 table
Scalability of broadcast performance in wireless network-on-chip
Networks-on-Chip (NoCs) are currently the paradigm of choice to interconnect the cores of a chip multiprocessor. However, conventional NoCs may not suffice to fulfill the on-chip communication requirements of processors with hundreds or thousands of cores. The main reason is that the performance of such networks drops as the number of cores grows, especially in the presence of multicast and broadcast traffic. This not only limits the scalability of current multiprocessor architectures, but also sets a performance wall that prevents the development of architectures that generate moderate-to-high levels of multicast. In this paper, a Wireless Network-on-Chip (WNoC) where all cores share a single broadband channel is presented. Such design is conceived to provide low latency and ordered delivery for multicast/broadcast traffic, in an attempt to complement a wireline NoC that will transport the rest of communication flows. To assess the feasibility of this approach, the network performance of WNoC is analyzed as a function of the system size and the channel capacity, and then compared to that of wireline NoCs with embedded multicast support. Based on this evaluation, preliminary results on the potential performance of the proposed hybrid scheme are provided, together with guidelines for the design of MAC protocols for WNoC.Peer ReviewedPostprint (published version
- …