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82
Matching output queueing with a combined input output queued switch
 IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
, 1999
"... The Internet is facing two problems simultaneously: there is a need for a faster switching/routing infrastructure, and a need to introduce guaranteed qualities of service (QoS). Each problem can be solved independently: switches and routers can be made faster by using inputqueued crossbars, instead ..."
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Cited by 146 (18 self)
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The Internet is facing two problems simultaneously: there is a need for a faster switching/routing infrastructure, and a need to introduce guaranteed qualities of service (QoS). Each problem can be solved independently: switches and routers can be made faster by using inputqueued crossbars, instead of shared memory systems; and QoS can be provided using WFQbased packet scheduling. However, until now, the two solutions have been mutually exclusive  all of the work on WFQbased scheduling algorithms has required that switches/routers use outputqueueing, or centralized shared memory. This paper demonstrates that a Combined Input Output Queueing (CIOQ) switch running twice as fast as an inputqueued switch can provide precise emulation of a broad class of packet scheduling algorithms, including WFQ and strict priorities. More precisely, we show that for an switch, a "speedup" of is necessary and a speedup of two is sufficient for this exact emulation. Perhaps most interestingly, this result holds for all traffic arrival patterns. On its own, the result is primarily a theoretical observation; it shows that it is possible to emulate purely OQ switches with CIOQ switches running at approximately twice the linerate. To make the result more practical, we introduce several scheduling algorithms that, with a speedup of two, can emulate an OQ switch. We focus our attention on the simplest of these algorithms, Critical Cells First (CCF), and consider its runningtime and implementation complexity. We conclude that additional techniques are required to make the scheduling algorithms implementable at high speed, and propose two specific strategies.
Topology Control and Routing in Ad hoc Networks: A Survey
 SIGACT News
, 2002
"... this article, we review some of the characteristic features of ad hoc networks, formulate problems and survey research work done in the area. We focus on two basic problem domains: topology control, the problem of computing and maintaining a connected topology among the network nodes, and routing. T ..."
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Cited by 115 (0 self)
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this article, we review some of the characteristic features of ad hoc networks, formulate problems and survey research work done in the area. We focus on two basic problem domains: topology control, the problem of computing and maintaining a connected topology among the network nodes, and routing. This article is not intended to be a comprehensive survey on ad hoc networking. The choice of the problems discussed in this article are somewhat biased by the research interests of the author
Universal Stability Results for Greedy ContentionResolution Protocols
 JOURNAL OF THE ACM
, 1996
"... In this paper, we analyze the behavior of communication networks in which packets are generated dynamically at the nodes and routed in discrete time steps across the edges. We focus on a basic adversarial model of packet generation and path determination for which the timeaveraged injection rate o ..."
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Cited by 107 (17 self)
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In this paper, we analyze the behavior of communication networks in which packets are generated dynamically at the nodes and routed in discrete time steps across the edges. We focus on a basic adversarial model of packet generation and path determination for which the timeaveraged injection rate of packets requiring the use of any edge is limited to be less than 1. A crucial issue that arises in such a setting is that of stability  will the number of packets in the system remain bounded, as the system runs for an arbitrarily long period of time? Among other things, we show: (i) There exist simple greedy protocols that are stable for all networks. (ii) There exist other commonlyused protocols (such as FIFO) and networks (such as arrays and hypercubes) that are not stable. (iii) The nnode ring is stable for all greedy routing protocols (with maximum queuesize and packet delay that is linear in n). (iv) There exists a simple distributed randomized greedy protocol that is st...
Stability of Adaptive and NonAdaptive Packet Routing Policies in Adversarial Queueing Networks
 In Proc. of the 31st STOC
, 2000
"... We investigate stability of packet routing policies in adversarial queueing networks. We provide a simple classification of networks which are stable under any greedy scheduling policy  network is stable if and only if the underlying undirected connected graph contains at most two edges. We also ..."
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Cited by 44 (3 self)
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We investigate stability of packet routing policies in adversarial queueing networks. We provide a simple classification of networks which are stable under any greedy scheduling policy  network is stable if and only if the underlying undirected connected graph contains at most two edges. We also propose a simple and distributed policy which is stable in an arbitrary adversarial queueing network even for the critical value of the arrival rate r = 1. Finally, a simple and checkable network flow type load condition is formulated for adaptive adversarial queueing networks and a policy is proposed which achieves stability under this new load condition. This load condition is a relaxation of the integral network flow type condition considered previously in the literature.
Simple Routing Strategies for Adversarial Systems
, 2001
"... In this paper we consider the problem of delivering dynamically changing input streams in dynamically changing networks where both the topology and the input streams can change in an unpredictable way. In particular, we present two simple distributed balancing algorithms (one for packet injections ..."
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Cited by 43 (4 self)
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In this paper we consider the problem of delivering dynamically changing input streams in dynamically changing networks where both the topology and the input streams can change in an unpredictable way. In particular, we present two simple distributed balancing algorithms (one for packet injections and one for flow injections) and show that for the case of a single receiver these algorithms will always ensure that the number of packets in the system is bounded at any time step, even for an injection process that completely saturates the capacities of the available edges, and even if the network topology changes in a completely unpredictable way. We also show that the maximum number of packets or flow that can be in the system at any time is best possible by providing an (essentially) matching lower bound that holds for any online algorithm, whether distributed or not. Interestingly, our balancing algorithms do not only behave well in a completely adversarial setting. We show that also in the other extreme of a static network and a static injection pattern the algorithms will converge to a point in which they achieve an average routing time that is close to the best possible average routing time that can be achieved by any strategy. This demonstrates that there are simple algorithms that can be efficient at the same time for very different communication scenarios. To have such algorithms will be of particular importance for communication in wireless mobile ad hoc networks (or short MANETs), in which at some time the connections between mobile nodes and/or the rates of input streams may change quickly and unpredictably and at some other time may be quasi static. Supported by DARPA grant F306020020550 "A Cost Benefit Approach to Fault Tolerant Communicati...
Stability of Networks and Protocols in the Adversarial Queueing Model for Packet Routing
 Networks
"... The adversarial queueing theory model for packet routing was suggested by Borodin et al. [2]. We give a complete and simple characterization of all networks that are universally stable in this model. We show that the same characterization also holds for networks which are stable given that the pa ..."
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Cited by 40 (2 self)
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The adversarial queueing theory model for packet routing was suggested by Borodin et al. [2]. We give a complete and simple characterization of all networks that are universally stable in this model. We show that the same characterization also holds for networks which are stable given that the packet forwarding protocol is FIFO (First In First Out). We also show that a specific greedy protocol, SIS (Shortest In System), is stable against 0/1 stochastic adversaries. 1 The Adversarial Model for Packet Injection In traditional queueing theory, the source which generates network traffic is typically assumed to be stochastic. Adversarial Queueing Theory developed out of a recent need for more robust models for these sources. The growing complexity of network traffic makes it increasingly unrealistic to model traffic as, say, a Poisson stream. It is therefore desirable to have a general robust framework which makes as few assumptions about the network traffic as possible. Such a framew...
Distributed Packet Switching in Arbitrary Networks
 In Proceedings of the 28th Annual ACM Symposium on Theory of Computing
, 1996
"... In a seminal paper Leighton, Maggs, and Rao consider the packet scheduling problem when a single packet has to traverse each path. They show that there exists a schedule where each packet reaches its destination in O(C + D) steps, where C is the congestion and D is the dilation. The proof relies o ..."
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Cited by 34 (2 self)
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In a seminal paper Leighton, Maggs, and Rao consider the packet scheduling problem when a single packet has to traverse each path. They show that there exists a schedule where each packet reaches its destination in O(C + D) steps, where C is the congestion and D is the dilation. The proof relies on the Lov'asz Local Lemma, and hence is not algorithmic. In a followup paper Leighton and Maggs use an algorithmic version of the Local Lemma due to Beck to give centralized algorithms for the problem. Leighton, Maggs, and Rao also give a distributed randomized algorithm where all packets reach their destinations with high probability in O(C +D log n) steps. In this paper we develop techniques to guarantee the high probability of delivering packets without resorting to the Lov'asz Local Lemma. We improve the distributed algorithm for problems with relatively high dilation to O(C) + (log n) O(log n) D + poly(log n). We extend the techniques to handle the case of infinite streams of ...
UniversalStability Results and Performance Bounds for Greedy ContentionResolution Protocols
"... In this paper, we analyze the behavior of packetswitched communication networks in which packets arrive dynamically at the nodes and are routed in discrete time steps across the edges. We focus on a basic adversarial model of packet arrival and path determination for which the timeaveraged arriva ..."
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Cited by 33 (2 self)
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In this paper, we analyze the behavior of packetswitched communication networks in which packets arrive dynamically at the nodes and are routed in discrete time steps across the edges. We focus on a basic adversarial model of packet arrival and path determination for which the timeaveraged arrival rate of packets requiring the use of any edge is limited to be less than 1. This model can reflect the behavior of connectionoriented networks with transient connections (such as ATM networks) as well as connectionless networks (such as the Internet). We concentrate on
Stability of Adversarial Queues via Fluid Models
 In Proceedings of the 39th Annual Symposium on Foundations of Computer Science
, 1998
"... The subject of this paper is stability properties of adversarial queueing networks. Such queueing systems are used to model packet switch communication networks, in which packets are generated and routed dynamically, and have become a subject of research focus recently. Adversarial queueing networks ..."
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Cited by 30 (3 self)
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The subject of this paper is stability properties of adversarial queueing networks. Such queueing systems are used to model packet switch communication networks, in which packets are generated and routed dynamically, and have become a subject of research focus recently. Adversarial queueing networks are defined to be stable, if the number of packets stays bounded over time. A central question is determining which adversarial queueing networks are stable, when an arbitrary greedy packet routing policy is implemented. In this paper we show how stability of a queueing network can be determined by considering an associated fluid models. Our main result is that the stability of the fluid model implies the stability of an underlying adversarial queueing network. This opens an opportunity for analyzing stability of adversarial networks, using established stability methods from continuous time processes, for example, the method of Lyapunov function or trajectory decomposition. We demonstrate t...
On Local Algorithms for Topology Control and Routing in Ad Hoc Networks
 In Proc. SPAA
, 2003
"... An ad hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any fixed infrastructure. Indeed, an important task of an ad hoc network is to determine an appropriate topology over which highlevel routing protocols are implemented. Furthermore, since the u ..."
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Cited by 28 (1 self)
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An ad hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any fixed infrastructure. Indeed, an important task of an ad hoc network is to determine an appropriate topology over which highlevel routing protocols are implemented. Furthermore, since the underlying topology may change with time, we need to design routing algorithms that effectively react to dynamically changing network conditions. This paper studies algorithms...