waashk/dblp huggingface dataset:
high speed communication protocols for optical star coupler using wdm. a network with n stations connected via a passive star coupler using wavelength division multiplexing (wdm) is considered. each station is equipped with a transmitter, transmitting at a fixed frequency, and a tunable receiver, capable of receiving frequencies over the entire transmitting spectrum. two reservation-based protocols are proposed for a local area network (lan) environment: the dynamic allocation scheme (das), which dynamically assigns slots on a packet-by-packet basis, and the hybrid tdm scheme (htdm) which is a combination of tdm and the das, allowing both preassigned slot and dynamic slot assignment. analytical results are derived for the delay performance of the two schemes and these results are compared with that of the tdm. it is shown that the performance of das is close to optimal when the propagation delay is zero. however, it requires a large signaling bandwidth. on the other hand, htdm has lower signaling needs, provides lower delays when compared to tdm (particularly under nonuniform traffic conditions), and is capable of handling bursty data traffic. thus, htdm offers a more practical solution for implementation for lans
an investigation of application level performance in atm networks. the goal of the paper is to investigate the relation that exists between the performance guarantees provided by a network, and what users of the network ultimately get. the focus is on the relation that exists between packet losses in a network, and message loses experienced by the application. this investigation is carried out in the context of an atm network where network packets are of fixed size (cells), and the authors concentrate mostly on the impact of the application peak transmission rate. varying this parameter for a given source while keeping network cell losses constant can translate into significant variation in the loss probability of application messages. in the paper, the authors develop and solve an analytical model to evaluate this behavior, and a set of guidelines that applications can use to determine which performance guarantees to require from the network to erasure an appropriate level of service.
a congestion control algorithm for tree-based reliable multicast protocols. this paper contains a detailed description of the congestion control algorithm of tram, a tree-based reliable multicast protocol. this algorithm takes advantage of regular acknowledgements from the receivers that propagate back to the sender via the repair tree. this scalable feedback mechanism is used to collect receiver credits. complementing the windowing mechanism, packet transmission is smoothed by using a data rate commensurate with the window size. additional details, such as how to prune slow receivers, and how to implement the rate scheduler on non-real-time systems are also discussed. the performance of the congestion control algorithm is then evaluated in extended lans, and wide area networks. the fairness of bandwidth-sharing with other (tcp) traffic is also evaluated.
openet: an open and efficient control platform for atm networks. atm networks are currently moving from the experimental stage of test-beds to a commercial state where production networks are deployed and operated. the atm forum pnni (private network to network interface) standard introduces an architecture suited for an internetwork which, in principle, can also be used as an intra-network nodal interface. however, the current pnni falls short in providing an acceptable solution due to severe performance limitations in intra-network operation, limited functionality and the lack of open interfaces for functional extensions and services. openet is a common, open and high-performance network control platform based on performance and functional enhancements to the pnni platform. it is designed to address the issues of interoperability (being vendor independent), scalability (in terms of network size and volume of calls), high performance (in terms of call processing latency and throughput) and functionality. openet is mainly an intra-networking extension to current pnni. it is compatible with pnni in the internetwork environment where large networks must be partitioned according to natural topological or organizational boundaries. the major novelty of the openet architecture (compared to the current pnni) is its focus on network control performance. a particular emphasis is given to the increase of the overall rate of connection handling, to the reduction of the call establishment latency and to the efficient utilization of the network resources. these performance enhancements are achieved by the use of a native atm distribution tree for the dissemination of utilization update, light-weight call setup, take down and modification signaling, the use of fast setup and takedown with the future option to implement them in hardware, and extensive use of caching and pre-calculation for route computation. openet also extends pnni in terms of functionality. it utilizes a new signaling paradigm that better supports fast reservation and multicast services, a rich control communication infrastructure which enables the development of augmented services leveraging the existing functions, messaging system and information of the network control platform.
optimal allocation of electronic content. the delivery of large files to individual users, such as video on demand or application programs to the envisioned network computers is expected by many to be one of the main tasks of broadband communication networks. this requires high bandwidth capacity as well as fast and dense storage servers. this motivates multimedia service providers to optimize the delivery network, as well as the electronic content allocation.a hierarchical architecture for the distribution of multimedia content was introduced by nussbaumer, patel, schaffa, and sterbenz (infocom 94). they addressed the trade-off between bandwidth and storage requirements that results from the placement of the content servers in the hierarchy tree. they presented a centralized algorithm to compute the best level of the hierarchy for the server location to minimize the combined cost of communication and storage.in this work we solve a general case where servers can be placed at different levels of the hierarchy. we develop a distributed optimal location algorithm that requires small nodal memory capacity and computational power. previous results for related problems for caching system design are of higher complexity. previous results for related classic operations research problems are limited to centralized algorithms, based on linear programming, that are not easy to convert into distributed algorithms. instead, to obtain our results, we observed that the use of dynamic programming naturally lends itself to a distributed implementation.for the specific problem at hand, we also managed to find a natural function (a generalization of the problem) that simplifies the combination operation used in the design of a dynamic program.
on packet loss processes in high-speed networks. an efficient recursive computation methodology is introduced to obtain the exact distribution of the number of lost packets in a block of packet arrivals of a given size for different arrival models and a different number of sessions. the exact distribution is compared with the distribution obtained from an independence assumption on the loss probability of packets. numerical examples are provided to show that the exact distribution may be worse than the distribution obtained under the independence assumption for applications such as forward error correction or better for applications such as straight message retransmission
virtual queueing techniques for abr service: improving abr/vbr interaction. several algorithms have been proposed for the switch behavior for congestion control of available bit rate (abr) services. schemes such as the enhanced proportional rate control algorithm (eprca) and the dynamic max rate control algorithm (dmrca), which use the queue length as congestion indicator to make a simple approximation of the fair share converge to the actual fair share, have become popular, because they offer good performance and are simple to implement. in particular, with no vbr traffic in the network, dmrca has been shown to achieve fairness in all situations, good buffer control, and robust performance. in this paper, first we show that the performance of these schemes may degrade when abr traffic interacts with highly-bursty vbr traffic. if vbr traffic induces congestion in the network, the length of the abr queue cannot serve as a reliable indicator of congestion caused by abr traffic, and the schemes perform poorly, introducing considerable unfairness. then, we propose a simple technique to solve these problems. the switch constructs the length of a virtual queue which is not affected by the instantaneous behavior of vbr traffic, and does not depend on how the two types of traffic are served in order to share the common link capacity; thus, it can serve as a reliable indicator of congestion. we use this technique in dmrca with virtual queueing (dmrca_vq), and show that the new scheme achieves fair rate allocation to the abr connections also in presence of highly-bursty vbr traffic. dmrca_vq maintains the low hardware complexity of dmrca. the virtual queueing technique is a solution for the more general problem of separating rate allocation based on the queue length from scheduling of multiple queues for sharing a common resource.
performance of reservation based (quadro) wdm star networks. the authors introduce a common modeling framework making it possible to develop tractable analytic models of optical star networks with reservation-based control. reservation-based wavelength division multiplexing (wdm) optical star systems, and in particular the quadro-based receiver design, have the performance advantages of high capacity, low response time, and adaptability to changing traffic flows. using the modeling framework introduced, tractable approximate models of reservation-controlled wdm stars were derived. it was shown that the framework allows the representation of different control strategies, while resulting in only a very small error
a fast bypass algorithm for high-speed networks. suggests an algorithm that increases the reservation success probability for bursty traffic in high speed networks by adding flexibility to the construction of the routes. the algorithm is simple enough to be implemented by cheap hardware. it causes no additional delay to packets that use the original route, and a very small delay to the packets that are rerouted. in addition, the presented algorithm has a minimal communication overhead due to the local nature of its work. two high-speed network models are considered: source routing and atm.
analysis of one-way reservation algorithms. modern high speed networks (and atm networks in particular) use resource reservation as a basic means of establishing communications. one-way on-the-fly reservation is a method for allocating resources for short bursts of data when regular reservation is too costly. the first such algorithms were recently suggested by turner. we investigate two examples that are characteristic to the way traffic streams interact in virtual circuit networks: a three node subnetwork that also acts as a 4/spl times/2 switch and a ring. for both systems we compute system throughput under homogeneous load, and compare it with the throughput when fast reservation protocols are used. for the three node subnetwork we also give an explicit expression for an upper bound.
multi-path routing combined with resource reservation. in high-speed networks it is desirable to interleave routing and resource (such as bandwidth) reservation. the pnni standard for private atm networks is a recent example for an algorithm that does this using a sequential crank-back mechanism. in this work, we suggest to do resource reservation along several routes in parallel. we present an analytical model that demonstrates that when there are several routes to the destination it pays to attempt reservation along more than a single route. following this analytic observation, we present a family of algorithms that route and reserve resources along parallel subroutes. the algorithms of the family represent different trade-offs between the speed and the quality of the established route. the presented algorithms are simulated against several legacy algorithm, including pnni crank-back, and exhibit higher network utilization and faster connection set-up time.
the programmable network prototyping system. the programmable network prototyping system (pnps) uses a collection of reusable hardware modules that implement generic communications functions such as transmission, reception, signal propagation, and pattern matching. these modules are interconnected and configured to emulate a variety of communication networks whose behavior can be monitored under different load conditions. the user specifies a network as a set of interacting components using available software tools. these tools are accessible within a prototyping environment that includes a control system for configuring the hardware modules and interconnecting them according to the component specifications. previously designed components are stored in a library and can be used to specify new networks. although pnps is designed to provide a prototyping environment for communication networks, some of the basic ideas can be useful in other contexts.
a new method to determine the queue length distribution at an atm multiplexer. in this paper, we develop a simple analytical technique to determine p({q>q}), the tail of the queue length distribution, at an atm multiplexer. the atm multiplexer is modeled as a fluid queue serving a large number of independent sources. our method is based on the central limit theorem and the maximum variance approximation, and enables us to avoid the state explosion problem. the approach is quite general and not limited by a markovian framework. we apply our analytical method to study the buffer behavior for various traffic sources such as multiplexed homogeneous and heterogeneous markov modulated sources, sources that are correlated at multiple time scales, sources whose autocorrelation function exhibits heavy (sub-exponential) tail behavior, and sources generated from real mpeg-encoded video sequences.
on the all-to-all broadcast problem in optical networks. this paper considers the transmission of uniform deterministic traffic in an optical broadcast-star network using wavelength division multiplexing. lower bounds are established on the minimum time to exchange information between every node pair in such a network with tunable transmitters and fixed-tuned receivers. three different scheduling algorithms are developed that are strictly optimal in three regimes of system parameters. the results are applicable to arbitrary tuning delays and arbitrary numbers of wavelength channels, and indicate the existence of a well-defined transition regime from tuning-limited operation to bandwidth-limited operation.
analysis of point-to-point packet delay in an operational network. in this paper, we perform a detailed analysis of point-to-point packet delay in an operational tier-1 network. the point-to-point delay is the time experienced by a packet from an ingress to an egress point in an isp, and it provides the most basic information regarding the delay performance of the isp's network. using packet traces captured in the operational network, we obtain precise point-to-point packet delay measurements and analyze the various factors affecting them. through a simple, step-by-step, systematic methodology and careful data analysis, we identify the major network factors that contribute to point-to-point packet delay and characterize their effect on the network delay performance. our findings are: (1) delay distributions vary greatly in shape, depending on the path and link utilization; (2) after constant factors dependent only on the path and packet size are removed, the 99th percentile variable delay remains under 1ms over several hops and under link utilization below 90% on a bottleneck; (3) a very small number of packets experience very large delay in short bursts.
a cellular wireless local area network with qos guarantees for heterogeneous traffic. a wireless local area network (wlan) or a cell with quality-of-service (qos) guarantees for various types of traffic is considered. a centralized (i.e., star) network topology is adopted as the topology of a cell which consists of a base station and a number of mobile clients. dynamic time division duplexed (tdd) transmission is used, and hence, the same frequency channel is time-shared for downlink and uplink transmissions under the dynamic control of the base station. we divide traffic into two classes: class i (real-time) and ii (non-real-time). whenever there is no eligible class-i traffic, class-ii traffic is transmitted, while uplink transmissions are controlled with a reservation scheme. class-i traffic is handled with the framing strategy combined with the admission test for adding new class-i connections. finally, we present the performance (average delay and throughput) evaluation of the reservation scheme for class-ii traffic using both analytical calculations and simulations.
associative search in peer to peer networks: harnessing latent semantics. the success of a p2p file-sharing network highly depends on the scalability and versatility of its search mechanism. two particularly desirable search features are scope (ability to find infrequent items) and support for partial-match queries (queries that contain typos or include a subset of keywords). while centralized-index architectures (such as napster) can support both these features, existing decentralized architectures seem to support at most one: prevailing unstructured p2p protocols (such as gnutella and fasttrack) deploy a ''blind'' search mechanism where the set of peers probed is unrelated to the query; thus they support partial-match queries but have limited scope. on the other extreme, the recently-proposed distributed hash tables (dhts) such as can and chord, couple index location with the item's hash value, and thus have good scope but can not effectively support partial-match queries. another hurdle to dhts deployment is their tight control of the overlay structure and the information (part of the index) each peer maintains, which makes them more sensitive to failures and frequent joins and disconnects. we develop a new class of decentralized p2p architectures. our design is based on unstructured architectures such as gnutella and fasttrack, and retains many of their appealing properties including support for partial match queries, and relative resilience to peer failures. yet, we obtain orders of magnitude improvement in the efficiency of locating rare items. our approach exploits associations inherent in human selections to steer the search process to peers that are more likely to have an answer to the query. we demonstrate the potential of associative search using models, analysis, and simulations.
mobile multi-layered ipsec. to achieve high throughput in wireless networks, smart forwarding and processing of packets in access routers is critical for overcoming the effects of the wireless links. however, these services cannot be provided if data sessions are protected using end-to-end encryption as with ipsec, because the information needed by these algorithms resides inside the portion of the packet that is encrypted, and can therefore not be used by the access routers. a previously proposed protocol, called multi-layered ipsec (ml-ipsec) modifies ipsec in a way so that certain portions of the datagram may be exposed to intermediate network elements, enabling these elements to provide performance enhancements. in this paper we extend ml-ipsec to deal with mobility and make it suitable for wireless networks. we define and implement an efficient key distribution protocol to enable fast ml-ipsec session initialization, and two mobility protocols that are compatible with mobile ip and maintain ml-ipsec sessions. our measurements show that, depending on the mobility protocol chosen, integrated mobile ip/ml-ipsec handoffs result in a pause of 53-100 milliseconds, of which only 28-75 milliseconds may be attributed to ml-ipsec. further, we provide detailed discussion and performance measurements of our mml-ipsec implementation. we find the resulting protocol, when coupled with snoop, greatly increases throughput over scenarios using standard tcp over ipsec (165% on average). by profiling the mml-ipsec implementation, we determine the bottleneck to be sending packets over the wireless link. in addition, we propose and implement an extension to mml-ipsec, called dynamic mml-ipsec, in which a flow may switch between plaintext, ipsec and mml-ipsec. using dynamic mml-ipsec, we can balance the tradeoff between performance and security.
configuring sessions in programmable networks. the provision of advanced computational services within networks is rapidly becoming both feasible and economical. we present a general approach to the problem of configuring application sessions that require intermediate processing by showing how the session configuration problem can be transformed to a conventional shortest path problem for unicast sessions or to a conventional steiner tree problem for multicast sessions. we study both a capacity-constrained version of the problem and an unconstrained version and show, through a series of examples, that the method can be applied to a wide variety of different situations. particularly, we show how to extend dijkstra's shortest path algorithm for use on the constrained version, and show that this approach can make significantly better use of network resources.
refreshment policies for web content caches. web content caches are often placed between end users and origin servers as a mean to reduce server load, network usage, and ultimately, user-perceived latency. cached objects typically have associated expiration times, after which they are considered stale and must be validated with a remote server (origin or another cache) before they can be sent to a client. a considerable fraction of cache "hits" involve stale copies that turned out to be current. these validations of current objects have small message size, but nonetheless, often induce latency comparable to full-fledged cache misses. thus, the functionality of caches as a latency-reducing mechanism highly depends not only on content availability but also on its freshness. we propose policies for caches to proactively validate selected objects as they become stale, and thus allow for more client requests to be processed locally. our policies operate within the existing protocols and exploit natural properties of request patterns such as frequency and recency. we evaluated and compared different policies using trace-based simulations.
efficient computation of end-to-end performance measures for multi-link atm networks with multi-media traffic. in this paper, we provide: (a) an efficient method for simplifying mmpp source models, which can be used to solve multi-media queueing problems with complicated aggregate input traffic. the effectiveness of the method is verified through numerical examples. (b) an approximation algorithm for analyzing multi-link queueing networks with mmpp traffic sources and arbitrary configurations. in this algorithm, a queueing network is analyzed by decomposing it into individual queues, each with an arrival rate appropriately reduced by the packet dropping occurred in other queues. each queue is then solved individually by using the simplified source models of (a) while the interdependencies with the other queues are accounted for through this reduced-load approximation. any desirable end-to-end performance measure characterizing the quality of service (qos) of the multi-media traffic can be calculated in this manner. the results obtained by the algorithm have been compared with simulation results, and the observed relative error is satisfactory.