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As the current Internet architecture is suffering from scalability issues, the network research community has proposed alternative designs for the Internet architecture. Among those solutions that adopt the idea of locator/identifier split paradigm, the locator/identifier separation protocol (LISP) has been considered as the most promising solution because of its incrementally deployable feature. Despite various advantages provided by LISP, many ISPs are still conservative to adopt LISP into their production network because the standard LISP does not fully satisfy ISP's requirements on LISP-enabled services. In this paper, we define ISP's requirements on LISP-enabled commercial services and describe limitations of the standard LISP from an ISP's perspective. Also, we propose LISP controller, a centralized LISP management system. By using LISP controller, we evaluate three ISP's representative LISP use cases: traffic engineering, virtual machine live migration, and vertical handover. The results show that the proposed LISP controller provides centralized management, controllability, and fast map entry update, without any modifications on the standard LISP. LISP controller allows an ISP to control and manage its LISP-enabled services while satisfying ISP's requirements. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Topic-based publish/subscribe is at the core of many distributed systems, ranging from application integration middleware to news dissemination. Therefore, much research was dedicated to publish/subscribe architectures and protocols, and in particular to the design of overlay networks for decentralized topic-based routing and efficient message dissemination. Nonetheless, existing systems fail to take full advantage of shared interests when disseminating information, hence suffering from high maintenance and traffic costs, or construct overlays that cope poorly with the scale and dynamism of large networks. In this paper, we present StaN, a decentralized protocol that optimizes the properties of gossip-based overlay networks for topic-based publish/subscribe by sharing a large number of physical connections without disrupting its logical properties. StaN relies only on local knowledge and operates by leveraging common interests among participants to improve global resource usage and promote topic and event scalability. The experimental evaluation under two real workloads, both via a real deployment and through simulation, shows that StaN provides an attractive infrastructure for scalable topic-based publish/subscribe. [ABSTRACT FROM PUBLISHER]

In this article, we build a simple engineeringeconomic model to evaluate the incentives of various network players to deploy distributed storage nodes (content stores and caches) to support information-centric network (ICN) architectures and the implications of those incentives on protocol design, industry structure and other policy issues, such as competition and network- neutrality. We find that without some explicit monetary compensation from publishers, networks will fail to deploy the socially optimal number of caches. We also study the social welfare implications of different cache deployment scenarios and identify two deployment scenarios that maximize social welfare. Finally, we show that ICN architectures provide numerous opportunities for large eyeball networks to leverage their terminating access monopoly to extract more profits from other network players. Hence, regulators must take steps to address issues such as interconnection and the role of caching infrastructure in differential quality of service provisioning in an ICN-based network architecture, in order to ensure socially desirable outcomes from their deployment. [ABSTRACT FROM PUBLISHER]

Networked cyber-physical systems are fundamentally constrained by the tight coupling and closed-loop control of physical processes. To address actuation in such closed-loop wireless control systems there is a strong need to rethink the communication architectures and protocols for reliability, coordination, and control. We introduce the Embedded Virtual Machine (EVM), a programming abstraction where controller tasks with their control and timing properties are maintained across physical node boundaries and functionality is capable of migrating to the most competent set of physical controllers. In the context of process and discrete control, an EVM is the distributed runtime system that dynamically selects primary-backup sets of controllers given spatial and temporal constraints of the underlying wireless network. EVM-based algorithms allow network control algorithms to operate seamlessly over less reliable wireless networks with topological changes. They introduce new capabilities such as predictable outcomes during sensor/actuator failure, adaptation to mode changes, and runtime optimization of resource consumption. An automated design flow from Simulink to platform-independent domain-specific languages, and subsequently, to platform-dependent code generation is presented. Through case studies in discrete and process control we demonstrate the capabilities of EVM-based wireless network control systems. [ABSTRACT FROM AUTHOR]

Since the original design of TCP and UDP, the world has changed, and with it, the Internet. Here, the authors argue that transport protocol architectures, most notably TCP's, must be updated to meet the needs of today's Internet. Their optimistic approach favors normal operation at the expense of overhead when dealing with corner cases and advocates leaving certain policies to the application instead of the transport protocol. [ABSTRACT FROM AUTHOR]

The inherent measurement support in routers (SNMP counters or NetFlow) is not sufficient to diagnose performance problems in IP networks, especially for flow-specific problems where the aggregate behavior within a router appears normal. Tomographic approaches to detect the location of such problems are not feasible in such cases as active probes can only catch aggregate characteristics. To address this problem, in this paper, we propose a Consistent NetFlow (CNF) architecture for measuring per-flow delay measurements within routers. CNF utilizes the existing NetFlow architecture that already reports the first and last timestamps per flow, and it proposes hash-based sampling to ensure that two adjacent routers record the same flows. We devise a novel Multiflow estimator that approximates the intermediate delay samples from other background flows to significantly improve the per-flow latency estimates compared to the naive estimator that only uses actual flow samples. In our experiments using real backbone traces and realistic delay models, we show that the Multiflow estimator is accurate with a median relative error of less than 20% for flows of size greater than 100 packets. We also show that Multiflow estimator performs two to three times better than a prior approach based on trajectory sampling at an equivalent packet sampling rate. [ABSTRACT FROM PUBLISHER]

The new generation network or the future Internet should treat mobile hosts as first-class objects and allow them to move freely across different networks that use heterogeneous protocols. For this purpose, this paper presents a mobility scheme, designed on the basis of the ID/locator split concept. The scheme provides mobility support from the identity layer, a shim layer inserted between the transport and network layers in the new generation network architecture. Mobility functions are independent of network layer protocols, thus they support mobility across heterogeneous network protocols. These functions are distributed in both end hosts and edge routers so that the scheme provides seamless mobility by reducing handover delay and consequent interruption in communication sessions. [ABSTRACT FROM AUTHOR]

Abstract: Group key management is an important functional building block for secure multicast architecture. Thereby, it has been extensively studied in the literature. The main proposed protocol is Adaptive Clustering for Scalable Group Key Management (ASGK). According to ASGK protocol, the multicast group is divided into clusters, where each cluster consists of areas of members. Each cluster uses its own Traffic Encryption Key (TEK). These clusters are updated periodically depending on the dynamism of the members during the secure session. The modified protocol has been proposed based on ASGK with some modifications to balance the number of affected members and the encryption/decryption overhead with any number of the areas when a member joins or leaves the group. This modified protocol is called Ancestors protocol. According to Ancestors protocol, every area receives the dynamism of the members from its parents. The main objective of the modified protocol is to reduce the number of affected members during the leaving and joining members, then 1 affects n overhead would be reduced. A comparative study has been done between ASGK protocol and the modified protocol. According to the comparative results, it found that the modified protocol is always outperforming the ASGK protocol. [ABSTRACT FROM AUTHOR]

Abstract: The backbone of ad hoc network design is energy performance and bandwidth resources limitations. Multi-rate adaptation architectures have been proposed to reduce the control overhead and to increase bandwidth utilization efficiency. In this paper, we propose a multi-rate protocol to provide the highest network performance under very low control overhead. The efficiency of the proposed auto multi-rate protocol is validated extensive simulations using QualNet network simulator. The simulation results demonstrate that our solution significantly improves the overall network performance. [ABSTRACT FROM AUTHOR]

Ad Hoc networks are susceptible to many attacks due to its unique characteristics such as open network architecture, stringent resource constraints, shared wireless medium and highly dynamic topology. The attacks can be of different types out of which denial of service is one of the most difficult attacks to detect and defend. Jellyfish is a new denial of service attack that exploits the end to end congestion control mechanism of TCP (Transmission Control Protocol) which has a very devastating effect on the throughput. The architecture for detection of such attack should be both distributed and cooperative to suit the needs of wireless ad-hoc networks that is every node in the wireless ad-hoc network should participate in the intrusion detection. We intend to develop an algorithm that detects the jellyfish attack at a single node and that can be effectively deployed at all other nodes in the ad hoc network. We propose the novel metric that detects the Jellyfish reorder attack based on the Reorder Density which is a basis for developing a metric. The comparison table shows the effectiveness of novel metric, it also helps protocol designers to develop the counter strategies for the attack. [ABSTRACT FROM AUTHOR]

Service discovery is a crucial operation for the usability of mobile ad hoc networks (MANETs). Traditional solutions to service discovery that were adopted on the Internet are not well suited for MANETs because of their dynamic nature. This paper presents a novel service discovery protocol based on a hierarchical grid architecture in an ad hoc network. The geographical area of a MANET is divided into a 2-D logical hierarchical grid. The proposed scheme registers the information of available services to a specific location along a predefined trajectory. To enhance resource availability and effective discovery, each grid cell selects a directory for caching available services. This paper utilizes the transmitting trajectory to improve the efficiency of registration and discovery. First, the service provider registers a service along the proposed register trajectory. The requestor then discovers the service along the discovery trajectory to acquire the service information. This paper also proposes an improved process to avoid the sparse node network topology. This paper adopts analysis and simulation to measure the protocol performance. The analytical and simulation results show that the proposed protocol can raise the discovery success ratio and reduce the discovery cost more than the existing geographical service discovery protocol. [ABSTRACT FROM AUTHOR]

We consider pipelined architectures of packet processors consisting of a sequence of simple packet-processing modules interconnected by first-in first-out buffers. We propose a new model for describing their function, an automated synthesis technique that generates efficient hardware for them, and an algorithm for computing minimum buffer sizes that allow such pipelines to achieve their maximum throughput. Our functional model provides a level of abstraction familiar to a network protocol designer; in particular, it does not require knowledge of register-transfer-level hardware design. Our synthesis tool implements the specified function in a sequential circuit that processes packet data a word at a time. Finally, our analysis technique computes the maximum throughput possible from the modules and then determines the smallest buffers that can achieve it. Experimental results conducted on industrial-strength examples suggest that our techniques are practical. Our synthesis algorithm can generate circuits that achieve 40 Gb/s on field-programmable gate arrays, equal to state-of-the-art manual implementations, and our buffer-sizing algorithm has a practically short runtime. Together, our techniques make it easier to quickly develop and deploy high-speed network switches. [ABSTRACT FROM AUTHOR]

This article investigates distributed cooperative medium access control protocol design for multihop wireless networks. Cooperative communication has been proposed recently as an effective way to mitigate channel impairments. With cooperation, single-antenna mobile terminals in a multi-user environment share antennas from other mobiles to generate a virtual multiple-antenna system that achieves more reliable communication with a higher diversity gain. However, more mobiles conscribed for one communication inevitably induces complex medium access interactions, especially in multihop wireless ad hoc networks. To improve the network throughput and diversity gain simultaneously, we investigate the issues and challenges in designing an efficient MAC scheme for such networks. Furthermore, based on the IEEE 802.11 DCF, a cross-layer designed cooperative MAC protocol is proposed. The MAC scheme adapts to the channel condition and payload length. [ABSTRACT FROM AUTHOR]

Recent studies demonstrated that dynamic spectrum access can improve spectrum utilization significantly by allowing secondary unlicensed users to dynamically share the spectrum that is not used by the primary licensed users. Cognitive radio was proposed to promote the spectrum utilization by opportunistically exploiting the existence of spectrum "holes." Meanwhile, cooperative relay technology is regarded widely as a key technology for increasing transmission diversity gain in various types of wireless networks, including cognitive radio networks. In this article, we first give a brief overview of the envisioned applications of: cooperative relay technology to CRNs, cooperative transmission of primary traffic by secondary users, cooperative transmission between secondary nodes to improve spatial diversity, and cooperative relay between secondary nodes to improve spectrum diversity. As the latter is a new direction, in this article we focus on this scenario and investigate a simple wireless network, where a spectrum-rich node is selected as the relay node to improve the performance between the source and the destination. With the introduction of cooperative relay, many unique problems should be considered, especially the issue for relay selection and spectrum allocation. To demonstrate the feasibility and performance of cooperative relay for cognitive radio, a new MAC protocol was proposed and implemented in a universal software radio peripheral-based testbed. Experimental results show that the throughput of the whole system is greatly increased by exploiting the benefit of cooperative relay. [ABSTRACT FROM AUTHOR]

Cooperative networking, by leveraging the broadcast nature of the wireless channel, significantly improves system performance and constitutes a promising technology for next-generation wireless networks. Although there is a large body of literature on cooperative communications, most of the work is limited to theoretical or simulation studies. To impact the next generation of wireless technologies and standards, it is essential to demonstrate that cooperative techniques indeed work in practice. This article describes two programmable cooperative communication testbeds built at Polytechnic Institute of NYU to achieve this goal. The testbeds are based on open- source platforms and enable implementation of cooperative networking protocols in both the physical and the medium access control layer. Extensive experiments carried out using the testbeds suggest not only that cooperative communication techniques can be integrated into current wireless technologies, but also that significant benefits of cooperation can be observed in terms of network throughput, delay, and video quality in real applications. [ABSTRACT FROM AUTHOR]

Abstract  This paper presents the design, implementation and evaluation of an extensible, scalable and distributed heterogeneous cluster based programmable router, called DHCR (Distributed Heterogeneous Cluster based Router), capable of supporting and deploying network services at run time. DHCR is a software IP router relying on heterogeneous cluster composed of separated computers with different hardware and software architecture capabilities, running different operating systems and interconnected through a high speed network connection. The DHCR ensures dynamic deployment of services and distributed control of router components (forwarding and routing elements) over heterogeneous system environments. The DHCR combines the IETF ForCES (Forwarding and Control Element Separation) architecture with software component technologies to meet the requirements of the next generation software routers. To ensure reliable and transparent communication between separated, decentralized and heterogeneous router components, the CORBA based middleware technology is used to support the DHCR internal communication. The paper also explores the use of the CORBA Component Model (CCM) to design and implement a modular, distributed and heterogeneous forwarding path for the DHCR router architecture. The CCM based forwarding plane ensures dynamic reconfiguration of the data path topology needed for low-level service deployment. Results on achievable performance using the proposed DHCR router are reported. [ABSTRACT FROM AUTHOR]

Recent trends in the telecommunication industry have been moving toward the development of ubiquitous information systems, where the provision of a plethora of advanced multimedia services should be possible, regardless of time and space limitations. An efficient and seamless delivery of multimedia services over various types of wireless networks is still a challenging task. The underlying difficulty consists of the disparity in the bandwidth availability over each network type. Indeed, the fundamental challenge upon a handoff phenomenon in a heterogeneous wireless network consists of an efficient probing of the bandwidth availability of the new network, followed by a prompt adjustment of the data delivery rate. This paper presents a cross-layer approach that involves five layers, namely, physical, data link, application, network, and transport layers. The three former layers are used to anticipate the handoff occurrence and to locate the new point of attachment to the network. Based on their feedback, the transport layer is used then to probe the resources of the new network using low-priority dummy packets. Being the most widely used protocol for multimedia delivery, this paper ad- dresses multimedia applications based on the Transmission Control Protocol (TCP) and the Real-time Transport Protocol (RTP). The design of the whole cross-layer architecture is discussed, and enhancements to the two protocols are proposed. The performance of the enhanced TCP and the RTP are evaluated and compared against existing schemes through extensive simulations. The obtained results are encouraging and promising for the delivery of multimedia services in heterogeneous wireless networks. [ABSTRACT FROM AUTHOR]

Traditional operating system interfaces and network protocol implementations force some system state to be kept on both sides of a connection. This state ties the connection to its endpoints, impedes transparent failover, permits denial-of-service attacks, and limits scalability. This article introduces a novel TCP-like transport protocol and a new interface to replace sockets that together enable all state to be kept on one endpoint, allowing the other endpoint, typically the server, to operate without any per-connection state. Called Trickles, this approach enables servers to scale well with increasing numbers of clients, consume fewer resources, and better resist denial-of-service attacks. Measurements on a full implementation in Linux indicate that Trickles achieves performance comparable to TCP/IP, interacts well with other flows, and scales well. Trickles also enables qualitatively different kinds of networked services. Services can be geographically replicated and contacted through an anycast primitive for improved availability and performance. Widely-deployed practices that currently have client-observable side effects, such as periodic server reboots, connection redirection, and failover, can be made transparent, and perform well, under Trickles. The protocol is secure against tampering and replay attacks, and the client interface is backward-compatible, requiring no changes to sockets-based client applications. [ABSTRACT FROM AUTHOR]

Abstract  The focus of this paper is to offer a practical multi-radio mesh network architecture that can realize the benefits of multiple radios. Our architecture provides solutions to challenges in three key areas. The first is the construction of a split wireless router that enables modular wireless mesh routers to be constructed from commodity hardware. The second is the design of a centralized channel assignment algorithm that considers the inter-dependence between channel assignment and routing in order to create high-throughput channel-diversified routes. Third is the design and implementation of several communication protocols that are necessary to make our architecture operational. Our system is comprehensively evaluated on a 20-node multi-radio wireless testbed. Results demonstrate that our architecture makes feasible the deployment of large-scale high-capacity multi-radio mesh networks built entirely with commodity hardware. Our implementation is available to the community for research and development purposes. [ABSTRACT FROM AUTHOR]

This paper proposes a new methodology to model the distribution of finite size content to a group of users connected through an overlay network. Our methodology describes the distribution process as a constrained stochastic graph process (CSGP), where the constraints dictated by the content distribution protocol and the characteristics of the overlay network define the interaction among nodes. A CSGP is a semi-Markov process whose state is described by the graph itself. CSGPs offer a powerful description technique that can be exploited by Monte Carlo integration methods to compute in a very efficient way not only the mean but also the full distribution of metrics such as the file download times or number of hops from the source to the receiving nodes. We model several distribution architectures based on trees and meshes as CSGPs and solve them numerically. We are able to study scenarios with a very large number of nodes and we can precisely quantify the performance differences between the tree and mesh-based distribution architectures. [ABSTRACT FROM AUTHOR]

In this paper, we present a new multicast architecture and the corresponding multicast routing protocol for providing efficient and flexible multicast services over the Internet. Traditional multicast protocols construct and update the multicast tree in a distributed manner, which may cause two problems: first, since each node has only local or partial information on the network topology and group membership, it is difficult to build an efficient multicast tree and, second, due to the lack of complete information, broadcast is often used for sending control packets and data packets, which consumes a great deal of network bandwidth. In the newly proposed multicast architecture, a few powerful routers, called m-routers, collect multicast-related information and process multicast requests based on the information collected. The m-routers handle most of the multicast-related tasks, whereas other routers in the network only need to perform minimum functions for routing. The m-routers are designed to be able to handle simultaneous many-to-many communications efficiently. The new multicast routing protocol, called the Service-Centric Multicast Protocol (SCMP), builds a shared multicast tree rooted at the m-router for each group. The multicast tree is computed in the m-router by employing the Delay-Constrained Dynamic Multicast (DCDM) algorithm, which dynamically builds a delay-constrained multicast tree and minimizes the tree cost as well. The physical construction of the multicast tree over the Internet is performed by a special type of self-routing packets in order to minimize the protocol overhead. Our simulation results on ns-2 demonstrate that the new SCMP protocol outperforms other existing protocols and is a promising alternative for providing efficient and flexible multicast services over the Internet. [ABSTRACT FROM AUTHOR]

Purpose - This paper deals with a cost-related evaluation and a comparison of the problems that arise on pure IP networks (i.e. big fat routers), IP over static optical networks (i.e. IP over synchronous digital hierarchy/optical transport network (SDH/OTN)) and IP over ASON/GMPLS-based dynamic optical network architectures. The aim is to develop easy-to-use CAPEX models, which can be evaluated using statistical parameters to describe the actual network and the traffic characteristics. Since there are no experimental results on these statistical parameters that can be practically used in real networks, the CAPEX model should be not only general, but also scalable enough to evaluate the network cost in extreme situations. Design/methodology/approach - In this paper, the comparative CAPEX models are developed (in the framework of the IST Project MUPBED - Multi-Partner European Test Beds for Research Networking) and the practical parameters are defined. Then the models are applied for the cost evaluation of a pan-European research network based on the GÉANT2 network topology to validate the simplified comparison technique that is proposed. Findings - The simulation results prove, on one hand, the applicability of the simplified cost models and on the other hand, the cost efficiency of the "IP over ASON/GMPLS" architecture. Originality/value - This paper deals with a cost-related evaluation and a comparison of the problems that are arise on pure IP networks, IP over static optical networks and IP over ASON/GMPLS-based dynamic optical network architectures. [ABSTRACT FROM AUTHOR]

The IMS Learning Design specification aims at capturing the complete learning flow of courses, without being restricted to a particular pedagogical model. Such flow description for a course, called a Unit of Learning, must be able to be reproduced in different systems using a so called run-time environment. In the last few years there has been several tools implementing such functionality, but most of them are standalone and do not benefit from the integration with a Learning Management System. This paper describes GRAIL, an IMS Learning Design run-time environment supporting all three levels of the specification and fully integrated with the .LRN Learning Management System. The paper describes its functionality, explains how each level is implemented, shows the differences with other CopperCore based environments, and analyzes its integration with the rest of .LRN services and other specifications such as QTI and SCORM. [ABSTRACT FROM AUTHOR]

EuQoS is the acronym for ‘end-to-end quality of service support over heterogeneous networks,’ which is a European research project aimed at building an entire QoS framework, addressing all the relevant network layers, protocols, and technologies. This framework, which includes the most common access networks (xDSL, UMTS, WiFi, and LAN) is being prototyped and tested in a multidomain scenario throughout Europe, composing what we call the EuQoS system. In this article we present the novel QoS routing mechanisms that are being developed and evaluated in the framework of this project. The preliminary performance results validate the design choices of the EuQoS system, and confirm the potential impact this project is likely to have in the near future. [ABSTRACT FROM AUTHOR]

Decentralized detection in a network of wireless sensor nodes involves the fusion of information about a phenomenon of interest (PoI) from geographically dispersed nodes. In this paper, we investigate the problem of binary decentralized detection in a dense and randomly deployed wireless sensor network (WSN), whereby the communication channels between the nodes and the fusion center are bandwidth-constrained. We consider a scenario in which sensor observations, conditioned on the alternate hypothesis, are independent but not identically distributed across the sensor nodes. We compare two different fusion architectures, namely, the parallel fusion architecture (PFA) and the cooperative fusion architecture (CFA), for such bandwidth-constrained WSNs, where each sensor node is restricted to send a 1-bit information to the fusion center. For each architecture, we derive expression for the probability of decision error at the fusion center. We propose a consensus flooding protocol for CFA and analyze its average energy consumption. We analyze the effects of PoI intensity, realistic link models, consensus flooding protocol, and network connectivity on the system reliability and average energy consumption for both fusion architectures. We demonstrate that a trade-off exists among spatial diversity gain, average energy consumption, delivery ratio of the consensus flooding protocol, network connectivity, node density, and PoI intensity in CFA. We then provide insight into the design of cooperative WSNs. [ABSTRACT FROM AUTHOR]

This article presents a vision for the emerging integrated optical networks to meet various traffic requirements and design criteria. To address the shortcomings in today's GMPLS over wavelength-routed optical networks, a new network architecture called Polymorphous, Agile, and Transparent Optical Networks (PATON) is proposed. PATON uses Polymorphous Optical Burst Switching (POBS) to seamlessly integrate different signaling, switching, and reservation schemes. The main features of PATON, along with its benefits as well as design and implementation challenges, are also described. Finally, both qualitative and quantitative performance comparisons of POBS with the two representative IP/GMPLS/OCS approaches are provided. [ABSTRACT FROM AUTHOR]

Load balancing is a critical issue for the efficient operation of peer-to-peer (P2P) networks. We give two new load-balancing protocols whose provable performance guarantees are within a constant factor of optimal. Our protocols refine the consistent hashing data structure that underlies the Chord (and Koorde) P2P network. Both preserve Chord's logarithmic query time and near-optimal data migration cost. Consistent hashing is an instance of the distributed hash table (DHT) paradigm for assigning items to nodes in a P2P system: items and nodes are mapped to a common address space, and nodes have to store all items residing closeby in the address space. Our first protocol balances the distribution of the key address space to nodes, which yields a load-balanced system when the DHT maps items "randomly" into the address space. To our knowledge, this yields the first P2P scheme simultaneously achieving O(log n) degree, O(log n) look-up cost, and constant-factor load balance (previous schemes settled for any two of the three). Our second protocol aims to balance directly the distribution of items among the nodes. This is useful when the distribution of items in the address space cannot be randomized. We give a simple protocol that balances load by moving nodes to arbitrary locations "where they are needed." As an application, we use the last protocol to give an optimal implementation of a distributed data structure for range searches on ordered data. [ABSTRACT FROM AUTHOR]

Next-generation wireless systems (NGWS) integrate different wireless networks, each of which is optimized for some specific services and coverage area to provide ubiquitous communications to the mobile users. It is an important and challenging issue to support seamless handoff management in this integrated architecture. The existing handoff management protocols are not sufficient to guarantee handoff support that is transparent to the applications in NOWS. In this work, a cross-layer (Layer 2 + 3) handoff management protocol, CHMP, is developed to support seamless intra and intersystem handoff management in NGWS. Cross-layer handoff management protocol uses mobile's speed and handoff signaling delay information to enhance the handoff performance of Mobile IP that is proposed to support mobility management in wireless IP networks. First, the handoff performance of Mobile P is analyzed with respect to its sensitivity to the link layer (Layer 2) and network layer (Layer 3) parameters. Then, a cross-layer handoff management architecture is developed using the insights learnt from the analysis. Based on this architecture, the detailed design of CHMP is carried out. Finally, extensive simulation experiments are carried out to evaluate the performance of CHMP. The theoretical analysis and simulation results show that CHMP significantly enhances the performance of both intra and intersystem handoffs. [ABSTRACT FROM AUTHOR]

The authors give an overview of current work on delay- and disruption-tolerant networking and review the overall architecture proposed by the Internet Research Task Force's Delay Tolerant Networking Research Group. Their approach to networking makes no assumption that nodes will have end-to-end connectivity, which could be missing with extremely high-latency connections, if the nodes are only in contact with one another infrequently or if contacts are being continually disrupted. They also describe the main protocols the group is developing and give examples of some pilot networks that use these protocols. [ABSTRACT FROM AUTHOR]

In most existing localized topology control protocols for mobile ad hoc networks (MANETs), each node selects a few logical neighbors based on location information and uses a small transmission range to cover those logical neighbors. Transmission range reduction conserves energy and bandwidth consumption, while still maintaining network connectivity. However, the majority of these approaches assume a static network without mobility. In a mobile environment network connectivity can be compromised by two types of ‘bad’ location information: inconsistent information, which makes a node select too few logical neighbors, and outdated information, which makes a node use too small a transmission range. In this paper, we first show some issues in existing topology control. Then, we propose a mobility-sensitive topology control method that extends many existing mobility-insensitive protocols. Two mechanisms are introduced: consistent local views that avoid inconsistent information and delay and mobility management that tolerate outdated information. The effectiveness of the proposed approach is confirmed through an extensive simulation study. [ABSTRACT FROM AUTHOR]

Protocols in the transport layer are basically classified by the amount of reliability they offer. Adoption of customized protocol, wherein the user can select the level of reliability for the pertinent communication, finds importance specifically in situations of activation and/or information retrieval of/from a robotized system. The developed architecture, Variable Reliability Dataflow Protocol (VRDP), provides transmission accountability in a transparent way, wherein users can select the degree of reliable connection necessary for the application. [ABSTRACT FROM AUTHOR]

The next generation of enterprise networks is undergoing major changes as a plethora of new architectures, applications, and services begin to roll out within businesses. In general, the world of voice/telephony, video, and data are "converging" into a global communications network. The purpose of this paper is twofold. First, the design, analysis, and performance of a session initiation protocol (SIP)-based videoconferencing desktop client, which has been developed and deployed over Internet2, is presented. Second, a guideline for managing SIP-based services to be deployed within enterprises, which addresses several challenges in each layer, such as network address translator (NAT)/FW issues, directory service integration issues, and interoperability issues, is proposed. Several detailed experimental results related to interoperability and conformance that were carried out are presented. Findings of extensive SIP/NAT traversal analysis through network traffic measurements are reported. The lessons learned from both the design of a new SIP-based voice/video client, as well as management challenges with enterprise deployment are highlighted. [ABSTRACT FROM AUTHOR]

Focuses on the capacity of Tangram to support virtual integration of internet protocol (IP) components in a distributed cosimulation environment. Key features of the Tangram environment; General approach to the evaluation of IP components; Comparison between Tangram and Distributed Cosimulation Backbone.

Innovations and developments in networking technology have been driven by technical considerations with little analysis of the benefit to the user. In this paper we argue that network parameters that define the network Quality of Service (QoS) must be driven by user-centric parameters such as user expectations and requirements for multimedia transmitted over a network. To this end a mechanism for mapping user-oriented parameters to network QoS parameters is outlined. The paper surveys existing methods for mapping user requirements to the network. An adaptable communication system is implemented to validate the mapping. The architecture adapts to varying network conditions caused by congestion so as to maintain user expectations and requirements. The paper also surveys research in the area of adaptable communications architectures and protocols. Our results show that such a user-biased approach to networking does bring tangible benefits to the user. [ABSTRACT FROM AUTHOR]

The impact of Van Jacobson header compression (VJHC) on the throughput performance of Transmission Control Protocol/Internet Protocol (TCP/IP) over lossy space channels is studied in an experimental manner using a test-bed. The experimental results show that VJHC benefits the transmission at bit error rates (BERs) around 10-6 or less, but also results in performance degradation in an environment with higher HER. [ABSTRACT FROM AUTHOR]

This article focuses on speculative incoherent cache protocols. Multiprocessing and multithreading are becoming ubiquitous even on single chips. With increasing cache sizes, coherence misses in such systems will account for a larger fraction of all cache misses. As communication latencies increase, this larger fraction of coherence misses will cause significant and increased performance losses. Tuning coherence proto- cols for specific communication patterns and applications can reduce communication latencies. Speculative execution has successfully improved performance in various scenarios. This article proposes a new type of load speculation, called coherence decoupling. This technique uses speculation to reduce the effect of long communication latencies without exacerbating the programmer's task or complicating the coherence protocol. Separating the SCL protocol and the coherence protocol enables designers to tune and optimize them independently, accelerating communication with less complexity than with conventional protocol optimizations. Separation also lets the two protocols overlap.

In-network collaborative computation is essential for implementation of a large number of sensor applications. We approach the problem of computation in sensor networks from a parallel and distributed system's perspective. We define COSMOS, the Cluster-based, heterOgeneouSMOdel for Sensor networks. The model abstracts the key features of the class of cluster-based sensor applications. It assumes a hierarchical network architecture comprising of a large number of low cost sensors with limited computation capability, and fewer number of powerful clusterheads, uniformly distributed in a two dimensional terrain. The sensors are organized into single hop clusters, each managed by a distinct clusterhead. The clusterheads are organized in a mesh-like topology. All sensors in a cluster are time synchronized, whereas the clusterheads communicate asynchronously. The sensors are assumed to have multiple power states and a wakeup mechanism to facilitate power management. To illustrate algorithm design using our model, we discuss implementation of algorithms for sorting and summing in sensor networks. [ABSTRACT FROM AUTHOR]

This paper introduces a novel policing mechanism, called Packet Leaky Bucket in which all cells of a frame are marked with the same level of priority. Moreover, it discusses the need for having a frame discard mechanism in cell-switched networks when frame-oriented policing mechanisms are used. [ABSTRACT FROM AUTHOR]

In this paper, we explore the constraints of a new problem: that of coordinating network troubleshooting among peer administrative domains and untrusted observers. Our approach permits any entity to report problems, whether it is a Network Operations Center (NOC), end-user, or application. Our goals are to define the inter-domain coordination problem clearly, and to develop an architecture which allows observers to report problems and receive timely feedback, regardless of their own locations and identities. By automating this process, we also relieve human bottlenecks at help desks and NOCs whenever possible. We present a troubleshooting approach for coordinating problem diagnosis, and describe Global Distributed Troubleshooting (GDT), a distributed protocol which realizes this approach. We show through simulation that GDT scales well as the number of observers and problems grows. [ABSTRACT FROM AUTHOR]

IPv6 has been designed, among other things, to provide an expanded address space to satisfy the future networking requirements. In this article we analyze and discuss important aspects of IPv6 deployment scenarios, and propose the system architecture coexisting and integrating with IPv4/MPLS networks. We investigate on various IPv6 deployment strategies along with network design examples, Comparing these techniques. Then the IPv6 deployment in service provider environments is proposed. [ABSTRACT FROM AUTHOR]

This paper describes the architecture, implementation, and application of Windmill, a passive network protocol performance measurement tool. Windmill enables experimenters to measure a broad range of protocol performance metrics both by reconstructing application-level network protocols and by exposing the underlying protocol layers' events. Windmill is split into three functional components: a dynamically compiled Windmill Protocol Filter (WPF), a set of abstract protocol modules, and an extensible experiment engine. To demonstrate Windmill's utility, we present the results from several experiments. The first set of experiments validates a possible cause for the correlation between Internet routing instability and network bandwidth usage. The second set of experiments highlights Windmill's ability to act as a driver for a complementary active Internet measurement infrastructure, its ability to perform online data reduction, and the non-intrusive measurement of a closed system. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Focuses on home network configuration for Living network Control Protocol (LnCP), in order to make the network services and configuration user-friendly. Reasons for the unchanged market for networked appliances; Main benefits of home networking system; Description of the four layers of LnCP; Features of LnCP.

Introduces a different family of infrastructure IP and discusses how it can optimize manufacturing test and debugging as well as support configurably, especially in today's reconfigurable products. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on computer design and testing.

Presents a solution that integrates memory IP with test and repair IP in a composite infrastructure IP that ensures manufacturing and field repair efficiency and optimizes SoC yield. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on computer design and testing.