Tcp

TCP flows from applications such as the web or ftp are well supported by a Guaranteed Minimum Throughput Service (GMTS), which provides a minimum network throughput to the flow and, if possible, an extra throughput. We propose a scheme for a GMTS using Admission Control (AC) that is able to provide different minimum throughput to different users and that is suitable for "standard" TCP flows. Moreover, we consider a multidomain scenario where the scheme is used in one of the domains, and we propose some mechanisms for the interconnection with neighbor domains. The whole scheme uses a small set of packet classes in a core-stateless network where each class has a different discarding priority in queues assigned to it. The AC method involves only edge nodes and uses a special probing packet flow (marked as the highest discarding priority class) that is sent continuously from ingress to egress through a path. The available throughput in the path is obtained at the egress using measurements of flow aggregates, and then it is sent back to the ingress. At the ingress each flow is detected using an implicit way and then it is admission controlled. If it is accepted, it receives the GMTS and its packets are marked as the lowest discarding priority classes; otherwise, it receives a best-effort service. The scheme is evaluated through simulation in a simple "bottleneck" topology using different traffic loads consisting of "standard" TCP flows that carry files of varying sizes. The results prove that the scheme guarantees the requested throughput to accepted flows and achieves a high utilization of resources.

Conventional TCP suffers from poor performance on high bandwidth delay product links meant for supporting transmission rates of multi Gigabits per seconds (Gbps). This is largely due to TCP's congestion control algorithm, which can be slow in taking advantage of large amounts of available bandwidth. A number of high-speed variants have been proposed recently, the major ones being BIC TCP, CUBIC, FAST, High-Speed TCP, Layered TCP, Scalable TCP and XCP. In this paper an effort has been made to comparatively analyze the aforementioned protocols based on various parameters viz., Throughput, Fairness, Stability, Performance, Bandwidth Utilization and Responsiveness and study the limitations of these protocols meant for the High Speed Networks.

In this paper an effort has been made to study various Congestion control techniques used for reducing/easing the level of congestion and subsequently avoiding the congestion of the wired communication networks in general and High Speed Networks in particular. Many authors have suggested several congestion control techniques [32] & [33] and studied their behavior under various network conditions, for a range of parameters also under heterogeneous networking environments. A special effort has been made to study the problems associated with the TCP congestion control mechanisms and the several solutions that have been proposed to improve its performance. This analysis tries to study the limitations of the suggested solutions, based on various parameters and propose algorithms to overcome these limitations for the High Speed Networks.

The conventional TCP suffers from poor performance on high bandwidth delay product links meant for supporting data transmission rates of multi Gigabits per seconds (Gbps). This is mainly due to the fact that during congestion, the TCP"s congestion control algorithm reduces the congestion window cwnd to ½ and enters additive increase mode, which can be slow in taking advantage of large amounts of available bandwidth. In this paper we have presented a new model and to overcome the drawbacks of the TCP protocol and propose to carry out a study of the same based on various parameters viz., Throughput, Fairness, Stability, Performance and Bandwidth Utilization for supporting data transmission across the High Speed Networks.

The purpose of this paper is to work on the cross-layer design and study the impact of transport layer protocol; Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) on the quality of service parameters of ad hoc network using Improved Ad hoc On-Demand Distance Vector Routing(IAODV) protocol. IAODV has a cross-layer approach with improvements on the physical layer, data link layer and transport layer. It combines the effect of modifications in expanded ring search, wait time and time to live; and allows node participation only above a set energy level while establishing a route. At transport layer, selection of TCP or UDP protocol will help in optimizing the performance of overall ad hoc network. The simulation result indicates that UDP performs better for the specified optimized values of IAODV. Our results show that the improved protocol IAODV offers lower Energy consumption in the range of 12% to 23%, End to End Delay is reduced in the range of 12% to 27%. The performance on account of PDR remains same for both AODV and IAODV. By deploying UDP protocol for transport layer using Constant Bit Rate (CBR) traffic further improves the performance of the end to end delay, retransmissions and overhead over 30%. The performance of energy and packet delivery ratio remains unaffected.

Saratoga is a protocol for fast file transfers across dedicated links in private networks, using small amounts of feedback for loss recovery. It is in use to download large amounts of imaging data from remote-sensing satellites, where the link environment is highly asymmetric and uplinks are constrained. However, Saratoga lacks a rate-control mechanism to allow fair share with co-existing flows for simultaneous competing transfers, or for across the congested Internet where it must coexist fairly with TCP. TFRC, a selfand TCP-Friendly Rate Control mechanism, can be adopted for Saratoga and leverage its existing protocol information. Use of TFRC normally requires significant changes in protocol operation, including additional data in feedback. We design a sender-based TFRC for Saratoga, needing only simple modifications within the sender and using only existing feedback information. This sender-based TFRC is shown to share the bottleneck-bandwidth fairly under various network conditions, allowing Saratoga to be adapted for shared links or for the congested Internet, while still supporting the asymmetric environments that Saratoga was originally developed for. TABLE OF CONTENTS 1 INTRODUCTION .

We analyze the dynamic behavior of a single RED controlled queue interacting with a large population of idealized TCP sources, i.e., sources obeying the rules of linear increase and multiplicative decrease. The aggregate traffic from this population is modeled in terms of the time dependent expected value of the packet arrival rate which reacts to the packet loss taking place in the queue. The queue is described in terms of the time dependent expected values of the instantaneous queue length and of the exponentially averaged queue length, for which we also derive a pair of differential equations. This provides us with a complete model for the dynamics of the system which we use to explore transient and equilibrium behavior. The accuracy of the model is verified by comparison with simulated results.

Barrera, Daniel F. CONICET – Universidad de Buenos Aires. Buenos Aires, Argentina.Maggi, Alejandro Esteban. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Buenos Aires, Argentina.41−71A partir de series pluviométricas mensuales de seis localidades del Noroeste Argentino (NOA) en el período 1935/36 – 2015/16 construimos series de precipitación acumulada Octubre-Abril (O-A). Verificamos la ocurrencia de saltos climáticos en la precipitación, que están en armonía con la Transición Climática del Pacífico (TCP) de 1976/77. Mostramos que posteriormente a la TCP hubo un cambio significativo en la precipitación en la sub-región semiárida del NOA. Se hallaron tendencias decrecientes de la precipitación a partir de la década de 1990 en el NOA. Propusimos índices ENSO (El Niño – Southern Oscillation) acumulados sobre el período monzónico O-A construidos a partir del Southern Oscillation Index (SOI), Oceanic Niño Index (ONI) y Multiva...

Scalable reliable multicast protocols have been a focus of recent research, tackling the problem of efficient reliable data delivery to an arbitrarily large number of receivers. Yet, the common applications of multicast, such as multi-point file delivery, or video streaming from a media server, typically only involve a moderate number of receivers, such as a thousand or fewer. Moreover, because of the limited deployment of these specialized multicast protocols, it is common for applications to instead use multiple TCP connections, one for each receiver, to implement multi-point delivery when feasible, causing a significant demand on the transmission server and the downstream links. In this paper, we describe a multicast extension to TCP, called the Single-source Multicast Optimization (SMO), that optimizes this case of multipoint delivery, providing the benefits of multicast together with the familiar features and API of TCP. Our results from experiments based on a Linux implementation and performed on a test-bed show that TCP-SMO requires just a modest extension to the TCP implementation and provides the scalable performance of multicast up to over a thousand receivers, thereby satisfying the common case requirements. In addition, used with TCP-RTM (Real-Time Mode), TCP-SMO also supports real-time multimedia multicast applications well.

Scalable reliable multicast protocols have been a focus of recent research, tackling the problem of efficient reliable data delivery to an arbitrarily large number of receivers. Yet, the common applications of multicast, such as multi-point file delivery, or video streaming from a media server, typically only involve a moderate number of receivers, such as a thousand or fewer. Moreover, because of the limited deployment of these specialized multicast protocols, it is common for applications to instead use multiple TCP connections, one for each receiver, to implement multi-point delivery when feasible, causing a significant demand on the transmission server and the downstream links. In this paper, we describe a multicast extension to TCP, called the Single-source Multicast Optimization (SMO), that optimizes this case of multipoint delivery, providing the benefits of multicast together with the familiar features and API of TCP. Our results from experiments based on a Linux implementation and performed on a test-bed show that TCP-SMO requires just a modest extension to the TCP implementation and provides the scalable performance of multicast up to over a thousand receivers, thereby satisfying the common case requirements. In addition, used with TCP-RTM (Real-Time Mode), TCP-SMO also supports real-time multimedia multicast applications well.

Protocol (TCP) for emerging very-high bandwidth-delay product networks and suggest several congestion control schemes for parallel and single-flow TCP. Recently, several high-speed TCP proposals have been suggested to overcome the limited throughput achievable by single-flow TCP by modifying its congestion control mechanisms. A. Introduction .

Most of the traffic in today's network uses the Transmission Control Protocol (TCP) as the transport layer protocol for reliable end-to-end packet delivery. However, TCP considers packet loss to be the result of network congestion which makes it unsuitable for mobile wireless communication, where sporadic and temporary packet losses are usual due to fading, shadowing, hand-off and other radio effects. During the vertical hand-off between different wireless technologies, the problem of end-to-end connection and reliability management for TCP becomes more severe. Intermediate Switching Network (ISN) is an effective framework for vertical handover between the UMTS and the WLAN network. This paper evaluates the performance of TCP over ISN based framework. The proposed scheme uses a cross layer interaction between the data link and the transport layers to estimate TCP retransmit timeout and congestion window during handover. Simulation results establishes effectiveness of the proposed scheme.

Satellite systems will complement terrestrial networks where the network could not be deployed for technical or economical reasons. Moreover, the natural broadcasting capacity of satellite networks makes it a good companion to terrestrial networks. Then, future services will be deployed over networks that combine terrestrial and satellite systems. The infrastructure heterogeneity could be problematic, for instance because of the delays variety. This article presents the problem from the point of view of the transport layer, the layer directly connected to the application, and compares several solutions to help future service developers using such network configuration.

Recent measurement and simulation studies have revealed that wide area network traffic displays complex statistical characteristics-possibly multifractal scaling-on fine timescales, in addition to the well-known property of self-similar scaling on coarser timescales. In this paper we investigate the performance and network engineering significance of these fine timescale features using measured TCP and MPEG2 video traces, queueing simulations and analytical arguments. We demonstrate that the fine timescale features can affect performance substantially at low and intermediate utilizations, while the longer timescale self-similarity is important at intermediate and high utilizations. We relate the fine timescale structure in the measured TCP traces to flow controls, and show that UDP traffic-which is not flow controlled-lacks such fine timescale structure. Likewise we relate the fine timescale structure in video MPEG2 traces to sub-frame encoding. We show that it is possibly to construct a relatively parsimonious multifractal cascade model of fine timescale features that matches the queueing performance of both the TCP and video traces. We outline an analytical method to estimate performance for traffic that is self-similar on coarse timescales and multi-fractal on fine timescales, and show that the engineering problem of setting safe operating points for planning or admission controls can be signif- icantly influenced by fine timescale fluctuations in network traffic. The work reported here can be used to model the relevant characteristics of wide area traffic across a full range of engineering timescales, and can be the basis of more accurate network performance analysis and engineering.

The accumulation of individual fitness or wealth is modelled as a population game in which pairs of individuals are recurrently and randomly matched to play a game over a resource. In addition, all individuals have random access to a constant background resource, and * This manuscript builds upon an incomplete sketch by one of the authors, see Weibull (1999). We thank Ingela Alger, Jérôme Renault, Laurent Miclo, Daniel Waldenström, and two anonymous referees for comments and suggestions to an earlier version of the manuscript with the title "A model of wealth accumulation". Sylvain Gibaud ([email protected]) thanks Unité Mixte de Recherche 5219 for its financial support. Jörgen Weibull

Abstract—In this article, we consider candidate wireless tech-nologies such as IEEE 802.11b and IEEE 802.15.4 that can support medical and healthcare informatics applications. The main questions that we try to answer are: (1) is there any poten-tial for significant interference ...

In this study, α-TCP and β-TCP were successfully produced via a mechanochemical method from aragonite structures, Clinocardium ciliatum seashells, at 850°C, 1000°C, and 1200°C sintering temperatures. The characterization of the obtained materials was carried out via FT-IR, SEM/EDX, BET, XRD, ICP-OES analysis. Samples were soaked for 21 days in simulated body fluid (SBF) for a bioactivity test. Additionally, MTT assay was applied to determine the cell viability of samples. Bioactivity in vitro tests showed that bone-like hydroxyapatite formed when the α-TCP and β-TCP were soaked in SBF. TCP bioceramics had a noncytotoxicity effect on SAOS-2 osteoblast-like cells and cell viability increased in 1 to 7 days. The produced bioceramics have ideal pore sizes and properties that are suitable for supporting biological activities. Tris-HCl buffer solution was used to obtain the level of biodegradation. It was seen that α-TCP exhibited better dissolution features than β-TCP.

The transparency feature of All Optical Wavelength Division Multiplexing (WDM) Networks makes it an interesting topic of study. Although characterized by the high throughput, low bit error rate and low noise, Transparent Optical Networks are still considered prone to attacks. The transparency of the network and the lack of opto-electronic conversion allow malicious signals to propagate without being detected. This unnoticeable propagation results in performance degradation and damages the throughput of the network. While several approaches have been focusing on hardware based detective measures, this paper proposes a preventive throughput and attack aware algorithm based on secure topology design. This approach gives enough flexibility to the customer to choose the level of security and throughput that they want to achieve in the network. Namely, the algorithm aims at routing lightpaths in such a way as to minimize the worst case possible damage that can result from different physic...

We propose a model for Stochastic Hybrid Systems (SHSs) where transitions between discrete modes are triggered by stochastic events much like transitions between states of a continuoustime Markov chains. However, the rate at which transitions occur is allowed to depend both on the continuous and the discrete states of the SHS. Based on results available for Piecewise-Deterministic Markov Process (PDPs), we provide a formula for the extended generator of the SHS, which can be used to compute expectations and the overall distribution of the state. As an application, we construct a stochastic model for on-off TCP flows that considers both the congestion-avoidance and slow-start modes and takes directly into account the distribution of the number of bytes transmitted. Using the tools derived for SHSs, we model the dynamics of the moments of the sending rate by an infinite system of ODEs, which can be truncated to obtain an approximate finite-dimensional model. This model shows that, for transfer-size distributions reported in the literature, the standard deviation of the sending rate is much larger than its average. Moreover, the later seems to vary little with the probability of packet drop. This has significant implications for the design of congestion control mechanisms.

Saratoga is a protocol for fast file transfers across dedicated links in private networks, using small amounts of feedback for loss recovery. It is in use to download large amounts of imaging data from remote-sensing satellites, where the link environment is highly asymmetric and uplinks are constrained. However, Saratoga lacks a rate-control mechanism to allow fair share with co-existing flows for simultaneous competing transfers, or for across the congested Internet where it must coexist fairly with TCP. TFRC, a selfand TCP-Friendly Rate Control mechanism, can be adopted for Saratoga and leverage its existing protocol information. Use of TFRC normally requires significant changes in protocol operation, including additional data in feedback. We design a sender-based TFRC for Saratoga, needing only simple modifications within the sender and using only existing feedback information. This sender-based TFRC is shown to share the bottleneck-bandwidth fairly under various network conditions, allowing Saratoga to be adapted for shared links or for the congested Internet, while still supporting the asymmetric environments that Saratoga was originally developed for.

If optical routers are to become reality, we will need several new optical technologies, one of which is to build sufficiently large optical buffers. Building optical buffers for routers is daunting: Today's electronic routers often hold millions of packets, which is well beyond the capabilities of optical technology. In this paper, we argue that two new results offer a solution. First, we show that the size of buffers in backbone routers can be made very small-just about 20 packets per linecard-at the expense of a small loss in throughput. Second, we show that integrated delay line optical buffers can store a few dozen packets on a photonic chip. With the combination of these two results, we conclude that future Internet routers could use optical buffers.

Recent measurement and simulation studies have revealed that wide area network traffic displays complex statistical characteristics-possibly multifractal scaling-on fine timescales, in addition to the well-known property of self-similar scaling on coarser timescales. In this paper we investigate the performance and network engineering significance of these fine timescale features using measured TCP and MPEG2 video traces, queueing simulations and analytical arguments. We demonstrate that the fine timescale features can affect performance substantially at low and intermediate utilizations, while the longer timescale self-similarity is important at intermediate and high utilizations. We relate the fine timescale structure in the measured TCP traces to flow controls, and show that UDP traffic-which is not flow controlled-lacks such fine timescale structure. Likewise we relate the fine timescale structure in video MPEG2 traces to sub-frame encoding. We show that it is possibly to construct a relatively parsimonious multifractal cascade model of fine timescale features that matches the queueing performance of both the TCP and video traces. We outline an analytical method to estimate performance for traffic that is self-similar on coarse timescales and multi-fractal on fine timescales, and show that the engineering problem of setting safe operating points for planning or admission controls can be significantly influenced by fine timescale fluctuations in network traffic. The work reported here can be used to model the relevant characteristics of wide area traffic across a full range of engineering timescales, and can be the basis of more accurate network performance analysis and engineering.

Abstract: Wavelength Division Multiplexing (WDM) is a promising solution for data transport in future all-optical wide area networks. Such networks consist of fibers joined by dynamically controllable cross-connects which provide purely optical transport between pairs of network access stations. Optical packet switching (OPS) is optical switching with the finest granularity. Incoming packets are switched all-optically without being converted to electrical signal. There are two categories of OPS networks. Slotted (synchronous) OPS networks, in which all the packets have the same size and unslotted (asynchronous) OPS networks, where packets may or may not have the same size. In this study we propose to integrate MPLS over slotted OPS networks by aggregating optical packets into a labeled optical burst. The burst has a fixed number of packets (segments). The number of segments in each burst is encoded in the experimental field of the MPLS header.

Yufeng Xin. Topology Design of Large-Scale Optical Networks. (Under the direction of Professor George N. Rouskas and Professor Harry G. Perros). Optical networks consisting of optical cross-connects(OXCs) arranged in some arbitrary topology are emerging as an integral part of the Internet infrastructure. The main functionality of these networks will be to provide reliable end-to-end lightpath connections to large numbers of electronic label switched routers (LSRs). We consider two problems that arise in building such networks. The first problem is related to the topology design of optical networks that can grow to Internet scales, while the second is related to the light-tree routing for the provision of optical multicast services.

Le travail réalisé tout au long de cette thèse n'a été possible qu'avec l'aide et le soutien de nombreuses personnes. Je profite de l'occasion qui m'est donnée ici pour leur exprimer toute ma gratitude. Je tenais en premier lieu à remercier vivement Jean-Jacques Pansiot, mon directeur de thèse, pour son encadrement et sa disponibilité. Merci Jean-Jacques de m'avoir fait partager tes connaissances, ton expérience et ta bonne humeur. Ce fut un réel plaisir de travailler pendant ces années sous ta direction. Je souhaite remercier chaleureusement Dominique Grad et Benoît Hilt, mes coencadrants de thèse, pour m'avoir prodigué de précieux conseils et pour m'avoir apporté de nombreuses idées au cours de ce travail. Je remercie Messieurs Guy Leduc, Thomas Noël, Vincent Roca et François Spies pour l'intérêt qu'ils ont porté à mes travaux en acceptant de faire partie de mon jury de thèse. Je tiens également à remercier toute l'équipe Réseaux et Protocoles du LSIIT. En particulier les doctorants présents et passés, avec qui j'ai beaucoup appris, partagé et apprécié travailler. Merci à Alexander, Damien, Émil, Julien, Julien, Mickaël, Pascal et Romain, pour votre disponibilité et votre gentillesse. Enfin, je remercie également ma famille et mes amis qui m'ont toujours soutenu, encouragé et sans qui je n'écrirais pas ces lignes. i vi independently of the reception rate. To deal with these problems, we propose a sequencer and its API, which assure that the more important the data is, the lower its sending rate is. And thus acquired by the majority of receivers. Experiments have shown the sequencer optimal performances insuring that a receiver subscribed to N% of the source rate obtains the most important N% of the applicative data. Moreover, applications can use this API without knowing anything about the dynamic layering used by M2C. Therefore, this API is easy to use, which makes it suitable for various kind of applications. Indeed, we have demonstrated the usefulness of the API and the underlying congestion control protocol by implementing two experimental applications : a file transfer [MU-TUAL] and a video streaming software [MUST].

TCP assumes that packet losses are due to congestion. Unfortunately, for the increasingly common case of wireless last hops, this may not be the case. The result is poor TCP performance. There has been significant research into this problem, but the solutions either require widespread changes to the network, or are architecturally limited. Network evolution of this sort is exactly the target of Active Networking (AN). We claim that if some network nodes were AN capable, the range of feasible and deployable solutions to this problem would be greatly increased. We support our claim by presenting a model and architecture of how AN might be deployed to address this problem. We then use this model and architecture to motivate a series of concrete implementations that address various aspects of the problem. These include an implementation of adaptive link control and of the Snoop protocol.

This study evaluated the biocompatibility of dense and porous forms of Poly(hydroxybutyrateco-hydroxyvalerate) (PHBV), Poly(ε-caprolactone) (PCL), and their 75/25 blend for bone tissue engineering applications. The biomaterials were characterized morphologically using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), and the thickness and porosity of the scaffolds were determined. Functional assessments of mesenchymal stem cells (MSCs) included the MTT assay, alkaline phosphatase (ALP) production, and morphological and cytochemical analyses. Moreover, these polymers were implanted into rats to evaluate their in vivo performance. The morphology and FTIR spectra of the scaffolds were consistent with the expected results. Porous polymers were thicker than dense polymers, and porosity was higher than 92% in all samples. The cells exhibited good viability, activity, and growth on the scaffolds. A higher number of cells was observed on dense polymers, likely due to their smaller surface area. ALP production occurred in all samples, but enzyme activity was more intense in PCL samples. The scaffolds did not interfere with the osteogenic capacity of MSCs, and mineralized nodules were present in all samples. Histological analysis revealed new bone formation in all samples, although pure PHBV exhibited lower results compared to the other blends. In vivo results indicated that dense PCL and the dense 75/25 blend were the best materials tested, with PCL tending to improve the performance of PHBV in vivo.

The increasing reliance on inter-organizational information exchange has raised significant concerns about the security of data and network infrastructures. Network monitoring plays a crucial role in mitigating these concerns, with tools like Wireshark and Snort forming the backbone of Intrusion Detection Systems (IDS). Initially developed as a packet inspection application, Wireshark is widely regarded for its user-friendly interface and intuitive packet-enhancement features, making it effective for classifying various types of network traffic. This research explores the practical application of Wireshark for network investigation, evaluating its role in conjunction with Snort to enhance IDS capabilities. The study examines potential improvements in these tools for heightened network security and their adaptability to emerging cyber threats. An experiment was conducted to assess the effectiveness of intrusion detection through real-time packet analysis, demonstrating the reliability of intrusive packet authentication within network environments. Wireshark was employed for real-time traffic inspection, capturing and analyzing packets, while Snort was used as the primary tool for detecting intrusions. The integration of Syslog and Snort facilitates the exchange of critical intrusion-related data, including packet counts, analysis of IPv4 packet conversations, and expert data on suspicious traffic. This study also focuses on the analysis of RSA-encrypted traffic and the evaluation of Local Area Networks (LAN) for signs of intrusion. Further, Wireshark's capabilities in monitoring and analyzing network activity were used to inspect TCP flags, generate I/O graphs for transmitted packet data, and produce TCP stream flow graphs for detecting intrusions. Additionally, the study includes TLS handshake analysis to identify abnormal or malicious network behavior. The use of ping requests from the attacker’s IP address to the victim’s IP address is highlighted as a method for detecting ongoing malicious activity. Through packet analysis, network traffic is classified as either malformed or well-formed, aiding in the identification of security breaches. Wireshark's in-depth packet inspection enables the detection of unauthorized access from both secure and insecure devices. This research not only explores Wireshark's utility in network intrusion detection but also evaluates emerging trends and challenges associated with IDS technologies. The findings contribute valuable insights for advancing future IDS research, particularly in adapting to the evolving landscape of network security threats. This technical evaluation highlights the importance of continuous development in tools like Wireshark and Snort to keep pace with the dynamic nature of cyberattacks, ensuring robust defense mechanisms for secure data transmission and network integrity.

In this document we show the evaluation of an already introduced handover management solution which can be used to provide ubiquitous connections and seamless Internet access. The new solution makes use of GNSS location information and previous records of network parameters. The method exploits the benefits of multihomed mobility configurations. Based on actual GNSS coordinates and previously recorded data, the system is able to predict handovers and to prepare itself for the appearance of networks. By implementing the proposed solution in a real-life multihomed test environment, handover latency is almost totally eliminated.

The reliability of data transfer is vital for commercial and enterprise applications of Wireless Sensor Networks (WSN). Likewise, mission-oriented and critical military applications of these networks demand dependable and timely data transport. This ...

In this paper we describe the current enabling Clustering technologies and present the design of the LNP (Legendary Now Project) 8-node low-end Linux machines cluster. The main focus is optimizing the TCP layer in the TCP/IP suite. We have implemented three basic modifications: eliminating redundancy in the computation of the checksums, modifying the queuing of small packets, and directing incoming packets to follow the slow-path by default. Eliminating the redundant computation of the checksum saved computation time on both the sender and receiver sides. Removing of the queuing of small packets accelerated their arrival time, and finally forwarding the incoming packets to follow the slow path by default saved computation time spent on prediction.

Abstract—The Sliding Window Protocol has long been established as an important network protocol in the ISO-OSI protocol stack. However the protocol cannot prevent the possibility of severe network degradation due to link failures. The paper explores a scenario when this might occur and proposes a solution to the problem using existing protocols and techniques. We analyze the behavior of the network at the Data Link Layer and use stochastic process modeling and the theory of blocking networks to identify parts of the protocol that might ...

Conventional TCP suffers from poor performance on high bandwidth delay product links meant for supporting transmission rates of multi Gigabits per seconds (Gbps). This is largely due to TCP's congestion control algorithm, which can be slow in taking advantage of large amounts of available bandwidth. A number of high-speed variants have been proposed recently, the major ones being BIC TCP, CUBIC, FAST, High-Speed TCP, Layered TCP, Scalable TCP and XCP. In this paper an effort has been made to comparatively analyze the aforementioned protocols based on various parameters viz., Throughput, Fairness, Stability, Performance, Bandwidth Utilization and Responsiveness and study the limitations of these protocols meant for the High Speed Networks.

Despite the architectural separation between intradomain and interdomain routing in the Internet, intradomain protocols do influence the path-selection process in the Border Gateway Protocol (BGP). When choosing between multiple equally-good BGP routes, a router selects the one with the closest egress point, based on the intradomain path cost. Under such hot-potato routing, an intradomain event can trigger BGP routing changes. To characterize the influence of hot-potato routing, we propose a technique for associating BGP routing changes with events visible in the intradomain protocol, and apply our algorithm to a tier-1 ISP backbone network. We show that (i) BGP updates can lag 60 seconds or more behind the intradomain event, (ii) the number of BGP path changes triggered by hot-potato routing has a nearly uniform distribution across destination prefixes, and (iii) the fraction of BGP messages triggered by intradomain changes varies significantly across time and router locations. We show that hot-potato routing changes lead to longer delays in forwarding-plane convergence, shifts in the flow of traffic to neighboring domains, extra externally-visible BGP update messages, and inaccuracies in Internet performance measurements. 1 To obtain up-to-date information about the size of routing tables, please reference http://www.cidr-report.org.

In this paper we demonstrate how an estimated functional kernel-regression polynomial from a particular RF technology can be created by the mobiles being served by that technology. A 3rd order polynomial description of the regression can be used to predict future throughput by observing the "pilot" quality prior to handover. The UE may use it to predict the throughput it will get in the new technology 50 to 200 m-sec prior to handover. The prediction can inform the Transport Control Protocol (TCP) layer or the application layer of the upcoming handover and the throughput expected after handover so that the user application receives the best quality of service. This paper is an extended version of the paper presented at IEEE Sarnoff Symposium 2015 [1]. It extends the paper with expanded foundational knowledge and explanation of the results and their implications. In this paper we: • propose that there is a way to predict the unobservable quality metrics in the new cell prior to commencement of the handover. This is achieved by 1) a prediction mechanism and 2) a signaling mechanism. In this paper we focus on the prediction mechanism. • propose that the observable metric ("pilot" quality) is predicted with prediction error below 9% with prediction step sizes of 200 m-sec.

A novel adsorbent for trichlorophenol (TCP) has been developed through the treatment of Chromolaena odorata (Odorata) with iodated table salt. Odorata is an abundant and problematic alien plant which we have found to be effective in removing TCP from aqueous solutions. Kinetic batch tests demonstrated that at pH 5, 99% of TCP could be removed from a solution given sufficient adsorbent loading rate and adsorption contact time with Odorata treated with table salt. Adsorption data were found to fit a 2-layer feed-forward artificial neural network (ANN) with 10 neurons using the Levenberg-Marquardt (trainlm) algorithm. The ability of Odorata to extract TCP from water was tested using equilibrium, kinetic and thermodynamic studies. Thermodynamic studies showed that the adsorption of TCP by the new adsorbent is thermally feasible and is governed by a chemical adsorption mechanism. It was established that the experimental data fit the selected adsorption isotherms in the following order: Langmuir > Freundlich > Temkin > Dubinin-Radushkevich (D-R). Kinetic modelling was done using intra-particle diffusion, liquid-film, pseudo-first order and pseudo-second order models. With the aid of the normalised standard deviation, the pseudo-second order was found to be the appropriate rate expression for the adsorption data. Liquid-film diffusion was the rate-determining stage of the adsorption process.

Problem statement: As the Internet becomes increasingly heterogeneous, the issue of congestion control becomes ever more important. And the link utilization is one of the important things in term of congestion avoidance and control mechanisms. And we can define the utilization as simply the throughput divided by the access rate. And also all the developments for the congestion control and avoidance algorithms interest about the using of network resources and use the links capacity (utilization). Approach: In this research we continued to study the performances of the New-Additive Increase Multiplicative Decrease (AIMD) algorithm as one of the core protocols for TCP congestion avoidance and control mechanism, we want now to evaluate the effect of using the AIMD algorithm after developing it to find a new approach, as we called it the New-AIMD algorithm to measure the bottleneck link utilization and use the NCTUns simulator to get the results after make the modification of the mechanism. And we will use the Droptail mechanism as Active Queue Management (AQM) in the bottleneck router. Results: After implementation of our new approach with different number of flows, we will measure the bottleneck link utilization and we will get high utilization (more than 94%)for bottleneck link with using this mechanism and avoid the collisions in the link. Conclusion: Now and after got this results as high utilization for bottleneck link, we know the New-AIMD mechanism work as well under the giving network condition in the experiments.

Since the TCP is the transport protocol for most Internet applications, evaluation of TCP throughput is important. In this paper, we establish a framework of evaluating TCP throughput by simple measurement. TCP throughput is generally measured by sending TCP traffic and monitoring its arrival or using data from captured packets, neither of which suits our proposal because of heavy loads and lack of scalability. While there has been much research into the analytical modeling of TCP behavior, this has not been concerned with the relationship between modeling and measurement. We thus propose a lightweight method for the evaluation of TCP throughput by associating measurement with TCP modeling. Our proposal is free from the defects of conventional methods, since measurement is performed to obtain the input parameters required to calculate TCP throughput. Numerical examples show the proposed framework's effectiveness.

This paper presents a study of nonlinear complex behaviour in UMTS networks. Using the fundamentals of chaos theory we explore the chaotic nature of the TCP protocol when used in 3G UMTS mobile networks. Furthermore we evaluate the impact of nonlinear dynamic behaviour on the UMTS network performance. In order to validate the concept of our investigation, a model of the UMTS network is built using OPNET™ modeller and simulated under various user traffic loads. Simulation results show the behaviour of the network with increasing traffic load, which ranges from periodically stable to chaotic with a direct impact on network performance.

Despite the fact that Transmission Control Protocol (TCP) is a stable and mature protocol, and has been well tuned over years, changes in its congestion control are still in progress without altering the fundamental underlying dynamics of TCP congestion control. In today's Internet, the network environment is more complex than ever. TCP's loss detection methods may falsely invoke retransmission even when the original packet is actually not lost. Such behavior is called Spurious Retransmission, which damages the TCP throughput greatly. In this article, we describe Spurious Timeout and Spurious Fast Retransmit, the causes for their occurrences, and the impacts that they have on TCP performance. Then we discuss the various detection and mitigation techniques available. To make TCP robust to these spurious retransmissions, we also provide some results of our comparative performance study of these detection and mitigation techniques.

Abstract: Automatically Switched Transport Network (ASTN) has many capabilities, such as dynamic connection/routing, that make it attractive for traffic engineering and optimization of next generation large scale optical mesh backbones. With increasing traffic demand spanning large geographic areas, optical mesh networks need to grow rapidly in terms of degree of meshing, bandwidth, and number of nodes. This translates (among others) into:(1) an increasing broadcast traffic and message load at each node in the ASTN control plane, ...

Cet article donne une formule explicite pour le débit moyen atteint par un flot TCP non persistant qui alterne entre des périodes de téléchargement et de lecture et dont les paquets subissent des pertes à taux constant. Il contient aussi des formules explicites pour la durée moyenne de téléchargement d'un fichier et pour la distribution du débit de transfert des données. Plusieurs classes de distributions de tailles de fichiers et de durées de lecture sont considérées, et notamment des distributions à queues lourdes. La formule du débit moyen se réduit à celle bien connue pour les flux persistants lorsque la taille des fichiers tend vers l'infini. Combinées à des méthodes de point fixe, ces formules peuvent être utilisées pour prédire le partage de la bande passante réalisé entre plusieurs flots HTTP par un mécanisme de contrôle actif de file d'attente de type AQM.