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18
Competitive Queue Policies for Differentiated Services
, 2000
"... We consider the setting of a network providing differentiated services. As is often the case in differentiated services, we assume that the packets are tagged as either being a high priority packet or a low priority packet. Outgoing links in the network are serviced by a single FIFO queue. ..."
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Cited by 51 (10 self)
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We consider the setting of a network providing differentiated services. As is often the case in differentiated services, we assume that the packets are tagged as either being a high priority packet or a low priority packet. Outgoing links in the network are serviced by a single FIFO queue.
Management of MultiQueue Switches in QoS Networks
 In Proc. 35th ACM Symp. on Theory of Computing
, 2003
"... The concept of Quality of Service (QoS) networks has gained growing attention recently, as the traffic volume in the Internet constantly increases, and QoS guarantees are essential to ensure proper operation of most communication based applications. A QoS switch serves m incoming queues by transmitt ..."
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Cited by 25 (5 self)
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The concept of Quality of Service (QoS) networks has gained growing attention recently, as the traffic volume in the Internet constantly increases, and QoS guarantees are essential to ensure proper operation of most communication based applications. A QoS switch serves m incoming queues by transmitting packets arriving at these queues through one output port, one packet per time unit. Each packet is marked with a value indicating its guaranteed quality of service. Since the queues have bounded capacity and the rate of arriving packets can be much higher than the transmission rate, packets can be lost due to insufficient queue space.
LossBounded Analysis for Differentiated Services.
, 2003
"... We consider a network providing Differentiated Services (DiffServ) which allow network service providers to offer different levels of Quality of Service (QoS) to different traffic streams. We focus on loss and first show that only trivial bounds could be obtained by means of traditional competitive ..."
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Cited by 23 (8 self)
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We consider a network providing Differentiated Services (DiffServ) which allow network service providers to offer different levels of Quality of Service (QoS) to different traffic streams. We focus on loss and first show that only trivial bounds could be obtained by means of traditional competitive analysis. Then we introduce a new approach for estimating loss of an online policy called lossbounded analysis. In lossbounded analysis the loss of an online policy is bounded by the loss of an optimal offline policy plus a constant fraction of the benefit of the online policy. We relate the lossbounded analysis to the throughputcompetitive analysis. We derive tight upper and lower bounds for various settings of DiffServ parameters using the new lossbounded model. We believe that lossbounded analysis is an important technique that can complement traditional competitive analysis providing new insight and interesting results.
Harmonic Buffer Management Policy for Shared Memory Switches
 Proceedings of INFOCOM 2002
, 2002
"... We introduce a new general scheme for shared memory nonpreemptive scheduling policies. Our scheme utilizes a system of inequalities and thresholds and accepts a packet if it does not violate any of the inequalities. We demonstrate that many of the existing policies can be described using our scheme ..."
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Cited by 19 (4 self)
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We introduce a new general scheme for shared memory nonpreemptive scheduling policies. Our scheme utilizes a system of inequalities and thresholds and accepts a packet if it does not violate any of the inequalities. We demonstrate that many of the existing policies can be described using our scheme, thus validating its generality. We propose a new scheduling policy, based on our general scheme, which we call the Harmonic policy. We analyze the Harmonic policy by means of competitive analysis and demonstrate that its throughput competitive ratio is almost optimal. Our simulations also show that the Harmonic policy both achieves high throughput and easily adapts to changing load conditions.
An improved algorithm for CIOQ switches
 Proc. 12th Annual European Symp. on Algorithms (ESA), Springer LNCS 3221
, 2004
"... Abstract The problem of maximizing the weighted throughput in various switching settings has beenintensively studied recently through competitive analysis. To date, the most general model that has been investigated is the standard CIOQ (Combined Input and Output Queued) switcharchitecture with inter ..."
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Cited by 11 (3 self)
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Abstract The problem of maximizing the weighted throughput in various switching settings has beenintensively studied recently through competitive analysis. To date, the most general model that has been investigated is the standard CIOQ (Combined Input and Output Queued) switcharchitecture with internal fabric speedup S> = 1. CIOQ switches, that comprise the backbone ofpacket routing networks, are N * N switches controlled by a switching policy that incorporatestwo components: Admission control and scheduling. An admission control strategy is essential to determine the packets stored in the FIFO queues in input and output ports, while the schedulingpolicy conducts the transfer of packets through the internal fabric, from input ports to output ports. The online problem of maximizing the total weighted throughput of CIOQ switcheswas recently investigated by Kesselman and Ros'en in [15]. They presented two different online algorithms for the general problem that achieve nonconstant competitive ratios (linear in eitherthe speedup or the number of distinct values, or logarithmic in the value range). We introduce the first constantcompetitive algorithm for the general case of the problem, with arbitraryspeedup and packet values. Specifically, our algorithm is 8competitive, and is also simple and easy to implement. 1 Introduction Overview: Recently, packet routing networks have become the dominant platform for data transfer. The backbone of such networks is composed of N * N switches, that accept packets through multiple incoming connections and route them through multiple outgoing connections. As network traffic continuously increases and traffic patterns constantly change, switches routinely have to efficiently cope with overloaded traffic, and are forced to discard packets due to insufficient buffer space, while attempting to forward the more valuable packets to their destinations.
An Experimental Study of New and Known Online Packet Buffering Algorithms
"... We present the first experimental study of online packet buffering algorithms for network switches. The design and analysis of such strategies has received considerable research attention in the theory community recently. We consider a basic scenario in which m queues of size B have to be maintained ..."
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Cited by 8 (0 self)
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We present the first experimental study of online packet buffering algorithms for network switches. The design and analysis of such strategies has received considerable research attention in the theory community recently. We consider a basic scenario in which m queues of size B have to be maintained so as to maximize the packet throughput. A Greedy strategy, which always serves the most populated queue, achieves a competitive ratio of only 2. Therefore, various online algorithms with improved competitive factors were developed in the literature. In this paper we first develop a new online algorithm, called HSFOD, which is especially designed to perform well under realworld conditions. We prove that its competitive ratio is equal to 2. The major part of this paper is devoted to the experimental study in which we have implemented all the proposed algorithms, including HSFOD, and tested them on packet traces from benchmark libraries. We have evaluated the experimentally observed competitivess, the running times, memory requirements and actual packet throughput of the strategies. The tests were performed for varying values of m and B as well as varying switch speeds. The extensive experiments demonstrate that despite a relatively high theoretical competitive ratio, heuristic and greedylike strategies are the methods of choice in a practical environment. In particular, HSFOD has the best experimentally observed competitiveness.
Buffer overflows of merging streams
 In Proc. 11th Annual European Symposium on Algorithms
, 2003
"... Abstract. We consider a network merging streams of packets with different quality of service (QoS) levels, where packets are transported from input links to output links via multiple merge stages. Each merge node is equipped with a finite buffer, and since the bandwidth of a link outgoing from a mer ..."
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Cited by 6 (0 self)
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Abstract. We consider a network merging streams of packets with different quality of service (QoS) levels, where packets are transported from input links to output links via multiple merge stages. Each merge node is equipped with a finite buffer, and since the bandwidth of a link outgoing from a merge node is in general smaller than the sum of incoming bandwidths, overflows may occur. QoS is modeled by assigning a positive value to each packet, and the goal of the system is to maximize the total value of packets transmitted on the output links. We assume that each buffer runs an independent local scheduling policy, and analyze FIFO policies that must deliver packets in the order they were received. We show that a simple local online algorithm called Greedy does essentially as well as the combination of locally optimal (offline) schedules. We introduce a concept we call the weakness of a link, defined as the ratio between the longest time a packet spends in the system before transmitted over the link, and the longest time a packet spends in that link’s buffer. We prove that for any tree, the competitive factor of Greedy is at most the maximal link weakness. 1
Packet routing and information gathering in lines, rings and trees
 In Proceedings of the 13th European Symposium on Algorithms (ESA
, 2005
"... We study the problem of online packet routing and information gathering in lines, rings and trees. A network consists of n nodes. At each node there is a buffer of size B. Each buffer can transmit one packet to the next buffer at each time step. The packets injection is under adversarial control. Pa ..."
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Cited by 6 (1 self)
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We study the problem of online packet routing and information gathering in lines, rings and trees. A network consists of n nodes. At each node there is a buffer of size B. Each buffer can transmit one packet to the next buffer at each time step. The packets injection is under adversarial control. Packets arriving at a full buffer must be discarded. In information gathering all packets have the same destination. If a packet reaches the destination it is absorbed. The goal is to maximize the number of absorbed packets. Previous studies have shown that even on the line topology this problem is difficult to handle by online algorithms. A lower bound of Ω ( √ n) on the competitiveness of the Greedy algorithm was presented by Aiello et al in [2]. All other known algorithms have a polynomial competitive ratio. In this paper we give the first O(log n) competitive deterministic algorithm for the information gathering problem in lines, rings and trees. We also consider multidestination routing where the destination of a packet may be any node. For lines and rings we show an O(log 2 n) competitive randomized algorithms. Both for information gathering and for the multidestination routing our results improve exponentially the previous results. 1
Universal Bounds on Buffer Size for Packetizing Fluid Policies in Input Queued, Crossbar Switches
, 2004
"... In this paper, we consider a type of online, traffic scheduling problem in input queued, crossbar switches. The input to a problem, at each time step, is a set of desired traffic rates. These traffic rates in general cannot be exactly achieved since they assume arbitrarily small fractions of packets ..."
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Cited by 3 (2 self)
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In this paper, we consider a type of online, traffic scheduling problem in input queued, crossbar switches. The input to a problem, at each time step, is a set of desired traffic rates. These traffic rates in general cannot be exactly achieved since they assume arbitrarily small fractions of packets can be transmitted at each time step. The goal of the traffic scheduling problem is to closely approximate the given sequence of traffic rates by a sequence of switch uses in which only whole packets are sent. The focus of this paper is bounding the costs incurred in using such an approximation, in terms of the additional buffer size required.