waashk/dblp huggingface dataset:
design of a fast restoration mechanism for virtual path-based atm networks. in this paper, we propose a fast restoration mechanism for virtual path-based atm networks. given an atm network topology, the capacity of each physical link, and the primary virtual path (vp) layout at system initialization, the proposed mechanism pre-assigns to each primary vp one backup vp such that (p1) the failure of a single node/link does not lead to the failure of both the primary and backup vps, (p2) the alternate backup vp is routed on a path with the shortest hop count among all possible paths with sufficient bandwidth between the two vp terminators, and (p3) the maximum link load is minimized.during system operation, if a physical node/link fails, the proposed mechanism restores the vps that traverse the failed node/link simply by redirecting cells on the failed vps to their corresponding backup vps. moreover, the proposed mechanism also locates (i) new vps for injured backup vps that traverse the failed node/link, and (ii) second-generation backup vps for newly-activated backup vps that replace their corresponding failed primary vps, both in a decentralized manner.we elaborate on all the component algorithms, and discuss how to configure the functionalities as software daemons that reside at each network node. the proposed mechanism is shown via event-driven simulation to be practically feasible in fast restoring failed vps in a cost effective manner.
multiconnection over multichannels. studies a multiconnection problem, in multichannel networks and proposes an effective multiconnection protocol for establishing and releasing connections with dynamic bandwidth requirement. each originating station in the network is allowed to set up connections to several terminating stations, and send packets to these terminating stations in different slots in a tdm fashion. similarly, each terminating station is allowed to keep connections with several originating stations, and receive packets from these originating stations in different slots in a tdm fashion. effective slot allocation schemes for multiple connections at the same station, as well as conditions for strict-sense acceptance and rearrangeable acceptance are given.
performance of multicasting closed interconnection networks. this paper examines the application of a simple yet general packet replication scheme to achieve multicasting in closed interconnection networks. the performance of these networks is studied and a general throughput equation is obtained to express the overall network throughput in terms of the average routing delay of the corresponding point-to-point network. the multicast performance results are thus built on top of the previously-established, and often simpler, point-to-point results. making use of this formula, we investigate the multicast closed shuffle-exchange network in detail. analytical results are compared with simulation results to obtain further insights into the network operation and ways to improve the network performance.
improving tcp/ip performance over third generation wireless networks. as third generation (3g) wireless networks with high data rate get widely deployed, optimizing tcp performance over these networks would have a broad and significant impact on data application performance. one of the biggest challenges in optimizing tcp performance over the 3g wireless networks is adapting to the significant delay and rate variations over the wireless channel. in this paper, we make two main contributions. first, we present a window regulator algorithm that uses the receiver window field in the acknowledgment packets to convey the instantaneous wireless channel conditions to the tcp source and an ack buffer to absorb the channel variations, thereby maximizing long-lived tcp performance. it improves the performance of tcp sack by up to 100\\% over a simple drop-tail policy with small buffer sizes at the congested router. second, we present a wireless channel and tcp-aware scheduling and buffer sharing algorithm that reduces the latency of short tcp flows while still exploiting user diversity for a wide range of user channel conditions.
experimental evaluation of atm congestion control mechanisms. a critical issue in the design of fast packet-switch-based networks is the avoidance of data loss due to congestion. in the context of atm networks, many link-level congestion control mechanisms for abr traffic have been proposed and simulated, and a few have been implemented. this paper presents, for the first time, an experimental comparison of several such mechanisms. to drive this comparison, we have developed a set of benchmarks that provide a quantitative characterization of congestion control performance. we also describe a simple but novel technique, the ``virtual port card'', for implementing both non-native switch behavior and long link delays in atm networks. this technique allows us to compare a wide range of mechanisms on a single flexible hardware platform. our measurements show that while several of the atm flow control mechanisms can eliminate cell loss, there are still several unresolved problems. first, for some traffic scenarios we see very poor application-level performance, especially in the presence of bursty traffic. second, performance is very sensitive to the flow control parameters and identifying an appropriate set of parameters is difficult since it depends heavily on the traffic conditions.
reliability analysis of sparse topologies for packet radio networks. four connectivity measures are used to compare the reliability of various sparse topologies for packet radio networks. different scenarios, including link failures, node failures, and both types of failures, were simulated for fixed-radius, nearest-neighbor, angle-constrained, degree-constrained, and delaunay triangulation-based topologies. the simulation results demonstrated that the commonly used fixed-radius topologies were the worst among all topologies tested. also, the results showed that triangulation-based and angle-constrained topologies maintained high reliability even under component failures
a filtering theory for deterministic traffic regulation. in this paper, we develop a filtering theory for deterministic traffic regulators that generate f-constrained outputs. we show that such regulators can be implemented by a linear time invariant filter with the impulse response f under the (min,+)-algebra if the function f is increasing and subadditive. the filtering approach not only yields easier proofs for more general results than those in the literature, but also allows us to design traffic regulators via systematic methods such as concatenation, filter bank summation, linear system realization, and fir-iir realization. the theory has many applications, including leaky buckets, traffic regulation for periodic constraint functions, and service curves. in particular, we find a new linear system realization and a new fir-iir realization for a concatenation of leaky buckets. moreover, we find a fir-iir realization for traffic regulators with periodic constraint functions. we also show that such regulators, in conjunction with maximum delay guarantee, guarantee shifted-subadditive service curves. based on this, we provide a couple of rules for service curve allocation among a concatenation of servers. the acm portal is published by the association for computing machinery. copyright © 2010 acm, inc. terms of usage privacy policy code of ethics contact us useful downloads: adobe acrobat quicktime windows media player real player
on algorithms searching for quasi-optimal subfamilies of gmw sequences suitable for cdma applications. this paper studies several algorithms for constructing quasi-optimal gmw subfamilies in terms of minimized bit error rate under co-channel interference. the results show that performance of resultant sub-families is very sensitive to the algorithms applied and sub-family sizes. a new criterion based on combinational (even plus odd) maximum cross-correlation is introduced for code selection and the resultant highest-peak-deleting and most-peak-deleting algorithms are effective to construct the gmw quasi-optimal sub-families.
computable exponential bounds for intree networks with routing. in this paper, we refine the calculus proposed previously by chang et al. (1994). the new calculus, including network operations for multiplexing, input-output relation, and routing, allows us to compute tighter exponential bounds for the tail distributions of queue lengths in intree networks with routing. in particular, if external arrival processes and routing processes are either markov arrival processes or autoregressive processes, the stationary queue length at a local node is stochastically bounded above by the sum of a constant and an erlang random variable. the decay rate of the erlang random variable is not greater than (in some cases equal to) the decay rate of the tail distribution of the stationary queue length. the number of stages of the erlang random variable is the number of external arrival processes and routing processes contributing to its queue length. for the single queue case, both the lower and upper-bounds are derived.
a bandwidth sharing theory for a large number of http-like connections. there has been tremendous progress in understanding how bandwidth is shared by tcp-like connections. by associating each tcp-like connection with a utility function, the bandwidth sharing problem of tcp-like connections can be modeled as a distributed optimization problem for utility functions. however, little is known on how bandwidth is shared by http-like connections through their utility functions at the tcp level. one of the main objectives of this paper is to provide a theory for bandwidth sharing of a large number of http-like connections. based on certain technical assumptions, we show that there is a utility function at the http level for an http-like connection and such a utility function can be derived from the utility function at the tcp level. the bandwidth is then shared by http-like connections through utility functions at the http level. we also address two possible extensions of the theory: the case with impatient tcp connections and the case with multiple types of requests. with appropriate modification of the utility functions at the http level, we show that the bandwidth is still shared by optimizing their utility functions at the http level for the case with impatient tcp connections. for the case with multiple types of requests, the bandwidth shared at the http level can still be found by solving a unique fixed point limit.
a buffer management scheme for the scoq switch under nonuniform traffic loading. the scoq switch is a batcher-banyan-based high-performance fast packet switch with shared concentration and output queuing, with a maximum of l(<n, the switch size) packets delivered to each output buffer in a slot. the authors consider the performance of the scoq switch under nonuniform traffic loading. based on the analysis of nonuniform traffic patterns, a buffer management congestion control scheme is proposed with the k=n/l output parts of each of the l switching modules sharing their buffering capacity. numerical results show that the buffer management scheme is effective
psd-based neural-net connection admission control. atm (asynchronous transfer mode) systems can support services with bursty traffic. an atm system needs a sophisticated and real-time connection admission controller not only to guarantee the required quality-of-service (qos) for existing calls but also to raise the system efficiency. input process has a power-spectral-density (psd) which explicitly contains the correlation behavior of input traffic and has a great impact on the system performance. also, a neural network has been widely applied to deal with traffic control related problems in atm systems because of its self-learning capability. in this paper, we propose a psd-based neural-net connection admission control (pncac) method for an atm system. under the qos constraint, we construct a decision hyperplane of the connection admission control according to parameters of the power spectrum. we further adopt the learning/adapting capabilities of the neural network to adjust the optimum location of the boundary between these two decision spaces. simulation results show that the pncac method provides a superior system utilization over the conventional cac schemes by an amount of 18%, while keeping the qos contract.
providing guaranteed rate services in the load balanced birkhoff-von neumann switches. in this paper, we propose two schemes for the load balanced birkhoff-von neumann switches to provide guaranteed rate services. the first scheme is based on an earliest eligible time first (eetf) policy. in such a scheme, we assign every packet of a guaranteed rate flow a targeted departure time that is the departure time from the corresponding work conserving link with capacity equal to the guaranteed rate. by implementing the eetf policy with jitter control mechanisms and first come first serve (fcfs) queues, we show that the end-to-end delay for every packet of a guaranteed rate flow is bounded by the sum of its targeted departure time and a constant that only depends on the number of flows and the size of the switch.our second scheme is a frame based scheme as in keslassy and mckeown, 2002. there, time slots are grouped into fixed size frames. packets are placed in appropriate bins (buffers) according to their arrival times and their flows. we show that if the incoming traffic satisfies certain rate assumptions, then the end-to-end delay for every packet and the size of the central buffers are both bounded by constants that only depend on the size of the switches and the frame size. the second scheme is much simpler than the first one in many aspects: 1) the on-line complexity is o(1) as there is no need for complicated scheduling; 2) central buffers are finite and thus can be built into a single chip; 3) connection patterns of the two switch fabrics are changed less frequently; 4) there is no need for resequencing-and-output buffer after the second stage; and 5) variable length packets may be handled without segmentation and reassembly.
nfs dynamics over flow-controlled wide area networks. the network file system protocol (nfs) has been the leading distributed file system for workstations since it was first introduced by sun microsystems in 1986. the geographical scale of nfs has been limited to the local area due to its relatively low performance on the wide area internet. however, with the advent of high bandwidth wide area networks such as atm, nfs over wans may become more promising. in this paper, the performance of nfs over various sizes of wan is studied. the effects of atm flow- control and queuing strategies on nfs are discussed, as are the performance of tcp and udp as nfs transport proto cols. the primary conclusion is that standard nfs over udp works well over atm wans as long as atm-level flow control keeps the cell loss rate under one percent. in some cases, nfs over tcp works badly with small packets due to unfortunate interactions with tcp's congestion window.
delay analyses of token-passing protocols with limited token holding times. the authors consider the ieee 802.4 token-bus, ieee 802.5 token-ring, and fiber distributed data interface (fddi) network standards. they perform the delay analyses for these token-passing network standards when all the network traffic is of the highest priority class. they model them in an unified manner as a cyclic-service system with exhaustive time-limited service policies. they have specifically considered two variants of the time-limited service policies-nonpreemptive and look-ahead. the former models the token-bus and the latter models the token-ring and fddi. the major result is an algorithm to approximate the mean delays for the nonpreemptive policy. numerical results show that the algorithm is reasonably accurate for deterministic and exponential frame sizes. the algorithm is applied to the performance analysis of a token-bus. a similar approach for the look-ahead policy is outlined
buffer sharing in conflict-free wdma networks. a wavelength division multiaccess network with buffer sharing among stations is studied. all stations in the network are connected to a passive optical star coupler and each station has a different fixed wavelength laser for transmitting packets. each station in the network reports its packet backlog to a scheduler which computes and then broadcasts a transmission schedule to all the stations through a control channel in each time slot. a transmission schedule includes two types of assignments: (1) to assign a maximum number of stations for conflict-free transmissions, and (2) to assign to relocation of packets from congested stations to uncongested relaying stations through idling transceivers for distributed buffer sharing. the major benefit is the reduction of packet loss due to buffer overflow. results show that as much as 75% of the buffers can be saved with buffer sharing
effective bandwidths of departure processes from queues with time varying capacities. in this paper, we consider a queue with a time varying capacity and identify the effective bandwidth of the stationary departure process from such a queue. two important observations are made: (i) the effective bandwidths for the transient departure process and the stationary departure process from such a queue are in general different, and (ii) sometimes it is necessary to build up the queue first in order to have a large excursion of the stationary departure process. the new result on the effective bandwidth of the stationary departure process is applied to intree networks with time varying capacities and priority tandem queues. algorithms for approximating the tail distributions of queue lengths in such networks are derived.
a simple architecture for atm switching systems. proposes a new self-routing atm switch. the switch is constructed based on a banyan network in which each inter-stage link is dilated by the stage number power of 2, each dilated link is concentrated from 2/sup d+1/ to 2/sup d/ multiple paths after stage d, and a new proposed shared-link design is used to reduce the cell blocking probabilities yielded by the concentration. by the scheme of interleaving the dilation, concentration, and sharing idle links after stage d, the new network has the advantages: (1) the delay-throughput performance is approximately the same as that of a knockout network with 2/sup d/ output links per output concentrator under the uniform traffic; (2) the hardware cost of network is of o(d2/sup d/nlogn)/spl ap/o(nlogn) as d is small; (3) the self-routing mechanism is very simple and identical to that of a banyan network; and (4) it is very feasible in vlsi design that only three simple and regular cmos chips are enough to construct any size of atm switch.
controlled request dqdb: achieving fairness and maximum throughput in the dqdb network. the author presents a new technique, called controlled request, to combat the unfairness problem in the distributed queue dual bus (dqdb) protocol that achieves 100% throughput. transmission of requests in the controlled request dqdb method is controlled by a mechanism that is similar to the one used in dqdb to transmit segments. fairness is achieved by using the bandwidth balancing technique to prevent an overloaded node form continuously transmitting requests. simulation studies showed that the controlled request dqdb scheme achieves better performance than the dqdb protocol with bandwidth balancing
matching output queueing with a combined input output queued switch. the internet is facing two problems simultaneously: we need a faster switching/routing infrastructure, and we need to introduce guaranteed qualities of service (qos). as a community, we have solutions to each: we can make the routers faster by using input-queued crossbard, instead of shared memory systems; and we can introduce qos using wfq-based packet scheduling. but we don''t know how to do both at the same time. until now, the two solutions have been mutually exclusive - all of the work on wfq- based scheduling algorithms has required that switches/routers use output- queueing, or centralized shared memory. we demonstrate that a combined input output queueing (cioq) switch running twice as fast as an input-queued switch can provide precise emulation of a broad class of packet scheduling algorithms, including wfq and strict priorities. more precisely, we show that a "speedup" of 2 - 1/n is both necessary and sufficient for this precise emulation. we introduce a variety of algorithms that configure the crossbar so that emulation is achieved with a speedup of two, and consider their running time and implementation complexity. we believe that, in the future, these results will make possible the support of qos in very high bandwidth routers.
alternative bandwidth allocation algorithms for packet video in atm networks. a two-node asynchronous transfer mode (atm) network is considered. several video sources are assumed multiplexed at the source node. five alternative algorithms for bandwidth allocation to video sources are considered using: static-slot assignment, buffer-population-based dynamic slot assignment, first-come-first-serve slot assignment and rate-based dynamic slot assignment. the average cell delay and the coefficient of variation of the delay for the five algorithms are determined by computer simulation and compared. it is concluded that the adaptive slot assignment algorithm and the buffer-population-based dynamic slot assignment algorithm are suitable for packet video in atm networks
layered required bandwidth for heterogeneous traffic. bandwidth is engineered for heterogeneous service via a layered notion of required bandwidth. the required bandwidth is requested to satisfy grade of service up to the layer of concern. the most important use of this layer required bandwidth is for bandwidth allocation at the path layer. the mathematical properties of the optimal policy are explored. based on these properties, a fast and accurate algorithm is derived for computing required bandwidth. numerical examples are given
a quantitative assured forwarding service. the assured forwarding (af) service of the ietf diffserv architecture provides a qualitative service differentiation between classes of traffic, in the sense that a low-priority class experiences higher loss rates and higher delays than a high-priority class. however, the af service does not quantify the difference in the service given to classes. in an effort to strengthen the service guarantees of the af service, we propose a quantitative assured forwarding service with absolute and proportional differentiation of loss, service rates, and packet delays. we present a feedback-based algorithm which enforces the desired class-level differentiation on a per-hop basis, without the need for admission control or signaling. measurement results from a testbed of freebsd pc-routers on a 100 mbps ethernet network show the effectiveness of the proposed service, and indicate that our implementation is suitable for networks with high data rates.