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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]

Next-generation networks introduce an IPbased network foundation and more powerful access technologies. As a result, vulnerabilities in network protocol implementations can be exploited with Internet hacking tools to cause denial-of-service and distributed denial of service situations. Fuzzing is a black-box testing technique originally used by crackers to find exploitable vulnerabilities. In this article, we demonstrate how specification-based fuzzers can be used to discover exploitable vulnerabilities proactively to make networks and devices more robust against DoS and DDoS attacks. [ABSTRACT FROM PUBLISHER]

In November 2011, the IEEE 802.3 Working Group approved the formation of a new Study Group chartered with examination of EPON over Coax (EPoC) technology. This article provides an overview of the market drivers, technical challenges, as well as deployment goals for this new technology. [ABSTRACT FROM PUBLISHER]

Cloud computing and other highly virtualized data center applications have placed many new and unique requirements on the data center network infrastructure. Conventional network protocols and architectures such as Spanning Tree Protocol and multichassis link aggregation can limit the scale, latency, throughput, and virtual machine mobility for large cloud networks. This has led to a multitude of new networking protocols and architectures. We present a tutorial on some of the key requirements for cloud computing networks and the various approaches that have been proposed to implement them. These include industry standards (e.g., TRILL, SPB, software-defined networking, and OpenFlow), best practices for standards-based data center networking (e.g., the open datacenter interoperable network), as well as vendor proprietary approaches (e.g., FabricPath, VCS, and Qfabric). [ABSTRACT FROM PUBLISHER]

IPv6 is an essential building block of the evolution toward the future Internet. To take the full benefit of this protocol and exploit all its features, the future Internet needs to gracefully couple it with autonomics. In this article we demonstrate through our experience with network renumbering how the coupling of both IPv6 core functionality extended with major functions of the autonomic world can lead to fully autonomous activities of main management functions. We instantiate the notions of self-configuration, self-monitoring, self-protection, and self-healing in the network renumbering process and show how all together they can make renumbering a real success. We illustrate the various functions with the tools we have implemented to support them. [ABSTRACT FROM AUTHOR]

Policy-based management allows the deployment of networks offering quality services in environments beyond the reach of real-time human control. A policy-based protocol stack middleware, the context-aware broker, has been developed by the authors to autonomically manage the remote deep space network. In this article example policy rules demonstrate the concept, and prototype results from ns-2.30 show the overall positive costbenefit impact in an example scenario. [ABSTRACT FROM AUTHOR]

The development of 100 Gb/s transponder technology is progressing rapidly to meet the needs of next-generation optical/IP carrier networks. Video-driven IP traffic growth continues together with the need for ever higher-speed ports on IP routers, Ethernet switches, and OTN cross-connects, thus driving the requirements for cost-effective client and line side 100 Gb/s transponders. For a short time to market, 100 Gb/s transponders should be deployable using 10 Gb/s link-engineering rules over existing fiber and DWDM infrastructure. In this article we describe the upgrade of an installed 10 Gb/s field system to 100 Gb/s using a real-time single-carrier coherent 100G polarization multiplexed quadrature phase shift keyed (PM-QPSK) channel. Performance sufficient for error-free operation after forward error correction was achieved over installed 900 km and 1800 km links, proving the viability of 100 Gb/s upgrades to most installed systems. Excellent tolerance to fiber polarization mode dispersion and narrowband optical filtering demonstrates the applicability of this technology over the majority of installed fiber plant and through existing 50 GHz reconfigurable optical add/drop multiplexers. [ABSTRACT FROM AUTHOR]

The recent advances in wireless client devices and the crucial role of multimedia communications in our society have motivated relevant standardization efforts, such as the IP multimedia subsystem, to support session control, mobility, and interoperability in all-IP next-generation networks. IMS has already driven the design of commercial mobile multimedia, but exhibits limited support for service continuity during handoffs. In particular, it omits advanced techniques to reduce/eliminate handoff delays, especially during vertical handoffs (i.e., change of the wireless technology employed by a client to access the wired Internet, e.g., from UMTS to WiFi). We propose an original solution for session continuity based on the primary design guideline of cleanly and effectively separating the signaling plane (for session reconfiguration via SIP) from the media delivery plane (data transmission and related handoff management operations). Our optimized handoff management techniques exploit terminal-based decentralized predictions to minimize service-level handoff delays. Different from other recent related work, our proposal fully complies with the standard IMS infrastructure and works at the application level. The reported experimental results point out that our solution, available as an open source tool for the IMS community, reduces playout interruption times relevantly by introducing a limited and scalable signaling overhead. [ABSTRACT FROM AUTHOR]

The IP multimedia subsystem defined by the Third Generation Partnership Project is the architecture merging the Internet and telecom worlds. The IMS was designed to make it easy for third-party developers to make their applications available to all IMS users, and by doing so provide more than only the basic telecom services like voice, messaging, presence and contact management. However, good knowledge of the IMS network architecture and the underlying Internet protocols is still needed to develop IMS applications. In addition, telecom expertise is needed to deploy the application and provision users. To ease the development and deployment process, it is essential to provide application developers with APIs and similar tools available for Web 2.0 application development today. In this article we explore the architectural and protocol aspects that enable third-party IMS application development and deployment. We also study how the applications will coexist with other applications already deployed in the IMS. Moreover, we describe Java libraries exploiting the functionality of the IMS both in the terminal client and within the core network. We also show how these Java libraries can be used for developing and deploying new applications in an IMS testbed, which provides IMS functionality over commercial 3G networks. [ABSTRACT FROM AUTHOR]

The ID/locator split concept has recently been introduced in the standardization activities of ITU-T Study Group 13 for use in future networks. To contribute to ITU-T's initiative, we first propose a naming system to configure hostnames and identifiers and map them to locators. We then propose a network architecture that isbased on the ID/locator split concept and the naming system. The proposed architecture allows the network layer to change protocols and locators without disturbing the upper-layer communication sessions. This capability is helpful for designing efficient solutions for mobility, multihoming, routing, and security as well as for integrating heterogeneous network layer protocols. [ABSTRACT FROM AUTHOR]

This article presents an overview of the IEEE project 802.15.5 that targets providing mesh capabilities to both high-rate and low-rate wireless personal area networks. Low-rate mesh is built on IEEE 802.15.4 MAC, while high-rate mesh utilizes IEEE 802.15.3 MAC. We seek to share our insights and motivations of the approach adopted in the major components of the standard instead of presenting a Ia carte items drawn in the specification. We hope this article helps readers of the 802.15.5 standard to better understand the rationale and intent of the protocol design. [ABSTRACT FROM AUTHOR]

We describe an emerging method of encryption suitable for high-speed optical communication networks. This encryption protocol combines traditional electronic cryptographic algorithms with the physical effect of optical noise of quantum origin to create a highly secure method of secret communications. The resulting optical signal is compatible with today's high speed fiber optic infrastructure including optical amplification and add/drop multiplexing. Systems implementing this protocol can be constructed with common commercially available components. We describe experimental results obtained with a 2.5 Gb/s system. The encrypted signal is shown to travel error-free through >500 km of optical fiber. Simulations show that reaches and data rates consistent with modern long haul optical networks are attainable. [ABSTRACT FROM AUTHOR]

With the knowledge that XG-PON is of primary interest to service providers as their preferred next generation optical access system, the investigation next turns to determining its technical specifications. This article presents the current thinking on the XG-PON systems. It presents a rough outline of the system design for the wavelength plan, the power budget, the protocol, and the management and service model. This work is likely to be the basis for standardization in upcoming ITU-T recommendations. [ABSTRACT FROM AUTHOR]

Cooperative communications fundamentally changes the abstraction of a wireless link and offers significant potential advantages for wireless networks. However, such technologies are evaluated with idealized scenarios where many control costs are assumed to be negligible. Moreover, even if these costs appear small in simple network scenarios, they increase significantly with the size and traffic level of the network, requiring careful evaluation, or even innovative design, of cooperative protocols to ensure their usefulness in realistic networks. This article describes a realistic evaluation of cooperative communications in a networking context. Insights obtained from this evaluation help guide work on cooperative communications toward practical and potentially beneficial protocols. [ABSTRACT FROM AUTHOR]

Cooperative communication has been shown to be an effective technique enabling singleantenna users to share their antennas to create a virtual MIMO system, thus providing extra spatial diversity in wireless networks. Distributed coding is a type of channel coding strategy developed for cooperative wireless networks. As opposed to conventional channel coding schemes, distributed coding constructs the whole codeword in a distributed manner among the cooperative users. Properly designed distributed coding can effectively approach the capacity of cooperative wireless networks. The aim of this article is to present an overview of recent development in distributed coding design in cooperative wireless networks. [ABSTRACT FROM AUTHOR]

Radio resource management algorithms ranging from bearer admission control to semi-persistent and dynamic packet scheduling, fast link adaptation, and transmission control of multi-antenna transmission modes are addressed in this article for UTRAN long-term evolution. First, a high-level system overview of LTE is given, with special emphasis on the important components related to RRM. The quality of service parameter framework is outlined, as one of the main objectives for the families of RRM algorithms is to maximize system capacity while serving all users according to their minimum QoS constraints. It is demonstrated how the collocation of the RRM algorithms at the base station with easy access to air interface measurements offers opportunities for efficient cross-functional optimization between layers 1, 2, and 3. Examples of performance results for different traffic mixes and antenna transmission schemes are also presented, and the article is concluded with recommendations on how to operate the various RRM options under different load and traffic conditions. [ABSTRACT FROM AUTHOR]

In this article we illustrate the performance of Transmission Control Protocol in an overlay cognitive radio network under dynamic spectrum access. We show that the performance of TCP in overlay CR networks that implement DSA to be quite different from its performance in conventional networks, which do not allow DSA. The key difference is that secondary users in an overlay CR network have to cope with a new type of loss called service interruption loss, due to the existence of primary users. We demonstrate on an NS2 simulation testbed the surprising result: Excessive radio resource usage leads to a decrease in aggregate TCP throughput. This behavior is in contrast to the behavior of TCP in conventional networks, where throughput increases monotonically with the available radio resource. [ABSTRACT FROM AUTHOR]

In this article we introduce a new cellular automata approach to construct an urban traffic mobility model. Based on the developed model, characteristics of global traffic patterns in urban areas are studied. Our results show that different control mechanisms used at intersections such as cycle duration, green split, and coordination of traffic lights have a significant effect on inter vehicle spacing distribution and traffic dynamics. These findings provide important insights into the network connectivity behavior of urban traffic, which are essential for designing appropriate routing protocols for vehicular ad hoc networks in urban scenarios. [ABSTRACT FROM AUTHOR]

This article describes requirements and fundamental technologies to enable the provision of a new generation network beyond the Internet and the next generation network, both of which are based on IP protocols. Although the Internet has grown into a social infrastructure and the NGN will replace legacy telephone networks and cellular phone networks in the near future, it is time to start R&D on revolutionary network technologies and clean-slate designed architecture beyond the IP structure. Here some R&D activities for a new generation network are shown. This article is a revised version of the author's presentation in the First ITU-T Kaleidoscope Academic Conference [1] held in Geneva last May. [ABSTRACT FROM AUTHOR]

The LTE radio interface for 3GPP Release 8 was specified recently. This article describes the LTE link-layer protocols, which abstract the physical layer and adapt its characteristics to match the requirements of higher layer protocols. The LTE link-layer protocols are optimized for low delay and low overhead and are simpler than their counterparts in UTRAN. The stateof-the-art LTE protocol design is the result of a careful crosslayer approach where the protocols interact with each other efficiently. This article provides a thorough overview of this protocol stack, including the sub-layers and corresponding interactions in between them, in a manner that is more intuitive than in the respective 3GPP specifications. [ABSTRACT FROM AUTHOR]

Modeling and simulation methods are employed by scientists and engineers to gain insight into system behavior that can lead to faster product time-to-market and more robust designs. These advantages come at the cost of model development time and the potential for questionable results because the model represents limited attributes of the actual system. M&S techniques are used to characterize complex interactions and performance at various layers of the protocol stack. This article provides a discussion of M&S for wireless network designers and developers, with particular attention paid to the architectural issues, as well as a discussion of the various communication M&S tools available today. The topics presented span the protocol stack, including radio-frequency-propagation M&S tools, physical-layer and waveform M&S, network-layer M&S, and distributed simulation, as well as waveform generation for test and evaluation. [ABSTRACT FROM AUTHOR]

This article describes the first multi-area multiprotocol label switching and generalized MPLS interoperability trial over a reconfigurable optical add/drop multiplexer and optical cross-connect network. The interoperability trial demonstrated the routing of label switched paths over a multi-area GMPLS controlled ROADM/OXC network and the control of Ethernet over MPLS transport service on top of the GMPLS network. The trial was conducted using various network elements provided by 14 institutions and was carried out in Tokyo and Virginia. This article introduces the motivation for the trial, technical issues related to controlling multi-area MPLS/GMPLS networks, test network topology, and experimental results. The results show that the interior gateway routing protocol-based multi-area routing architecture is a promising solution for the nationwide deployment of GMPLS networks within a carrier domain. In addition, this article discusses the technical issues of routing constraints in ROADM/OXC networks and the limit of multi-area routing without the Path Computation Element Protocol. [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]

As Ethernet traffic increases rapidly in carrier networks, service providers have an increasing need for Ethernet infrastructure networking in order to scale their Ethernet services. Ethernet infrastructure transports Ethernet traffic over distance, protects the traffic from link and nodal failures, and aggregates Ethernet connections from a large number of low-speed ports onto a much smaller number of high-speed ports. An Ethernet infrastructure allows service providers to inexpensively interconnect end user locations with one another for private line services, and to interconnect end users with the VPLS and IP/MPLS service edges for enterprise, residential, and mobility services. OAM and protection capabilities are critical to enable Ethernet to be deployed as an infrastructure technology. This article reviews several important developments in Ethernet OAM and protection standards, and discusses how those capabilities are vital for the creation of an effective Ethernet infrastructure. [ABSTRACT FROM AUTHOR]

The objective of this article is to give advice for carrying out a proper and effective simulation activity for protocol design. It challenges some of the existing criticisms of simulation practices that emphasized validation aspects. This article advocates the use of simple models, matching assumptions and metrics in the problem statement and simulation to provide a basic "proof of concept," and comparison with truly competing solutions, which is possible only after a thorough and critical literature review. Then the complexity of the models can be increased (one parameter at a time), revising the algorithms themselves by adapting them to new assumptions, metrics, and the corresponding simulation environment. Selected independent variables should explain performance under a wide range of scenarios. [ABSTRACT FROM AUTHOR]

This article describes and characterizes an emerging type of user-centric wireless network model, here named a user-provided network, where the end user is at the same time a consumer and a provider of Internet access. A discussion of challenges these new models face is also provided. [ABSTRACT FROM AUTHOR]

Wi-Fi access technology has become popular in recent years. Many users nowadays use Wi-Fi to gain wireless access to the Internet from offices, public libraries, shopping malls, homes, and other places. However, current Wi-Fi deployment is limited to areas where wired LAN is available. Due to its relatively short transmission range in indoor environments (typically several tens of meters), Wi-Fi coverage needs to be extended significantly to full coverage of a certain area. The wireless mesh network (WMN) is a practical and effective solution. In this article we present HomeMesh, an off-the-shelf, simple, and cost-effective WMN for the indoor home environment. HomeMesh is based on simple protocols, implementable in normal notebooks or PCs, and is compatible with existing Wi-Fi APs and clients (i.e., no AP and client modifications). To achieve better end-to-end delay and throughput, HomeMesh dynamically selects its access path based on the ETX metric. We have implemented HomeMesh and conducted proof- of-concept experiments in an indoor environment. Our mesh solution is shown to be effective in improving Wi-Fi services. [ABSTRACT FROM AUTHOR]

In this article, a novel network architecture called resilient burst ring is proposed to implement the next-generation WDM-supported ultrahigh-speed (100 gigabit or higher) carrier Ethernet. This architecture inherits all the best features of resilient packet ring (IEEE 802.17), provides a burst-mode data transmission scheme through a two-sublayer (optical and electronic) hierarchy, and realizes the WDM-supported ultra-high-speed Ethernet with scalability and reliability. RBR adopts a two-layer buffering scheme to resolve the contentions of optical burst packets and provides three different data transmission modes. With the proposed PriorityOnly-Destination-Delay resource reservation control protocol, RBR can provide a flexible Q0S strategy to implement the transmission of all of the applications and services in existing networks. [ABSTRACT FROM AUTHOR]

Advances in next-generation SONET/SDH have introduced novel features for generic protocol framing/encapsulation, virtual concatenation, inverse multiplexing, dynamic circuit adjustment, and so on. In turn, these provisions have enabled much improved multi-tiered service provisioning and are viewed very favorably by carriers, particularly incumbents. This article looks at this evolved framework with a particular focus on value-added services creation. Results from a sample performance evaluation study also are presented to quantify some of the achievable gains. [ABSTRACT FROM AUTHOR]

Research on vehicular ad hoc networks has focused mainly on efficient routing protocol design under conditions where there are relatively large numbers of closely spaced vehicles. These routing protocols are designed principally for urban areas with high node density and fully connected networks and are not suitable for packet delivery in a sparse, partially connected VANET. In this article, we examine the challenges of VANETs in sparse network conditions, review alternatives including epidemic routing, and propose a border node-based routing protocol for partially connected VANETs. The BBR protocol can tolerate network partition due to low node density and high node mobility. The performance of epidemic routing and BBR are evaluated with a geographic and traffic information-based mobility model that captures typical highway conditions. The simulation results show that under rural network conditions, a limited flooding protocol such as BBR performs well and offers the advantage of not relying on a location service required by other protocols proposed for VANETs. [ABSTRACT FROM AUTHOR]

Much progress can be observed in the domain of Vehicular Ad Hoc Network (VANET) research looking back at the last decade. It can be seen that studies of vehicular communication protocols in the context of VANETs are typically based on simulation models. This approach has two major prerequisites: First, detailed network simulation of all layers of communication protocols is necessary as provided by a wide variety of tools by the networking community. Secondly, realistic simulation of vehicles' mobility, i.e., an exact modeling of road traffic, is needed to estimate positions and movements of involved components. The contributions of this article are twofold: First, a survey of the evolution of mobility modeling in VANET simulations is provided, outlining the simulation strategies typically used. Secondly, this article investigates how recent advances in bidirectional coupling of road traffic microsimulation and network simulation lead to more realistic results at comparably low computational cost. In conclusion, this article advocates to employ such techniques that are openly available for further studies of new communication protocols and mechanisms in the domain of VANET research. [ABSTRACT FROM AUTHOR]

Vehicular networks are a very promising technology to increase traffic safety and efficiency, and to enable numerous other applications in the domain of vehicular communication. Proposed applications for VANETs have very diverse properties and often require nonstandard communication protocols. Moreover, the dynamics of the network due to vehicle movement further complicates the design of an appropriate comprehensive communication system. In this article we collect and categorize envisioned applications from various sources and classify the unique network characteristics of vehicular networks. Based on this analysis, we propose five distinct communication patterns that form the basis of almost all VANET applications. Both the analysis and the communication patterns shall deepen the understanding of VANETs and simplify further development of VANET communication systems. [ABSTRACT FROM AUTHOR]

Ethernet technologies are rapidly gaining importance as a prevailing solution for carrier networks. Ethernet ring protection switching, defined in ITU-T Recommendation G.8032, provides a means of achieving carrier network requirements for ring network topologies. This article outlines the novel concepts in this Ethernet ring protection switching mechanism and discusses the fundamental operating principles by which the automatic protection switching (APS) protocol works. In addition, several feature enhancements in protection behavior and solutions being considered for the next phase of standardization are discussed. [ABSTRACT FROM AUTHOR]

As data rates outpace the capabilities of electronic encryption schemes, photonic layer security may fill the gap in providing a communication security solution at high data rates. In this article we review and highlight the advantages of our proposed optical code-division multiplexed (OCDM)-based photonic layer security (PLS) system based on high-resolution control of the optical phase of tightly spaced phase locked laser lines. Such a PLS system is scaleable to 100 Gb/s and provides a protocol independent security solution. We review the use of high-resolution control of the optical phase of mode-locked laser frequency combs as an enabling technology for a new class of OCDM systems. A network based on such systems is compatible with and can have comparable spectral efficiency to existing DWDM networks. Through inverse multiplexing of 10 Gb/s tributaries, we have already demonstrated optical transmission of a 40 Gb/s aggregate OCDM signal over 400 km. Such a PLS solution is achieved through shared phase scrambling of the individual OCDM codes assigned to each of the tributaries using an integrated micro-ring resonator-based phase coder/scrambler. The confidentiality of OCDM-based PLS is robust against exhaustive, known plain text, and archival/forensic attacks, and can complement digital encryption operating at higher layers. Moreover, the integrity of the PLS solution is ensured through the inherent coupling to confidentiality, since knowledge of the key is needed in order to easily alter the transmitted data stream without introducing observable errors. This system can leverage advances in optical integration to support new applications where electronic encryption is impractical because of space, weight, power, availability, and cost requirements. Such applications range from timely security support for the emerging 100 GbE standards to all-optical multilevel security offered through the compatibility of PLS with transparent DWDM networks. [ABSTRACT FROM AUTHOR]

The article examines a possible way of improving the performance of the presence service within IMS networks without modifying the presence and group management enabler. This can be achieved by means of a presence network agent (PNA). The PNA has been defined by 3GPP in [1]; it is a new logic entity within the IMS core network that is able to publish the presence information on behalf of the presentity user agent. The PNA improves performance because it reduces the presence signaling load within the radio access network without downgrading the freshness and richness of the presence information. The article's goal is to provide the reader with useful information about the PNA and our experience with PNA implementation and deployment. We first describe the PNA concept as defined by 3GPP, highlighting the open issues still present in the standardization and the possible optimizations, subsequently we present an actual implementation of a PNA handling busy/idle states for IMS calls. [ABSTRACT FROM AUTHOR]

IEEE 802.15.4 is the global standard protocol designed for low-power and low-rate wireless personal area networks. When applied to sensor networks, extra care should be taken due to their requirements for multihop communication with minimum energy consumption. In this article we first discuss potential problems with the energy consumption in sensor networks using IEEE 802.15.4. Then six representative categories of algorithms are presented. The algorithms reside in between the MAC and a network layer. All operations of the MAC are performed through the standard interfaces of IEEE 802.15.4 without altering the standard protocol. The energy consumption and latency of the algorithms are evaluated by analysis and experiments, and the feasibility of real implementations is also discussed. [ABSTRACT FROM AUTHOR]

In this article we concentrate on the automated provisioning of inter-AS services based on GMPLS-TE technology. We consider a provider alliance where TE connections are established between the members of the alliance. We propose an efficient and economically feasible architecture for the automatic provisioning of inter-AS GMPLS-TE, based on the introduction of a multidomain service plane coupled with the PCE-based architecture. [ABSTRACT FROM AUTHOR]

This article describes the intercarrier external network-to-network interface development challenges at the Kei-han-na Info-Communications Open Laboratory. The E-NNI prototype that was developed provides interworking functionality between the automatically switched optical network control plane function of the ITU-T and the generalized multiprotocol label-switching control plane function of the IETF. In this article, an analysis of the differences between ASON network technologies and GMPLS network technologies, a detailed signaling protocol and routing protocol interworking mechanism, and the interworking experimental results of nationwide ASON and GMPLS network domains are described. [ABSTRACT FROM AUTHOR]

A particularly severe attack on routing protocols in ad hoc networks is the so-called worm- hole attack in which two or more colluding attackers record packets at one location, and tunnel them to another location for replay at that remote location. When this attack targets specifically routing control packets, the nodes that are close to the attackers are shielded from any alternative routes with more than one or two hops to the remote location. All routes are thus directed to the wormhole established by the attackers. In the optimized link state routing protocol, if a wormhole attack is launched during the propagation of link state packets, the wrong link information percolates throughout the network, leading to routing disruption. In this article we devise an efficient method to detect and avoid wormhole attacks in the OLSR protocol. This method first attempts to pinpoint links that may potentially be part of a wormhole tunnel. Then a proper wormhole detection mechanism is applied to suspicious links by means of an exchange of encrypted probing packets between the two supposed neighbors (endpoints of the wormhole). The proposed solution exhibits several advantages, among which are its nonreliance on any time synchronization or location information, and its high detection rate under various scenarios. [ABSTRACT FROM AUTHOR]

Enterprises are increasingly using Ethernet as the foundation for transforming their networks to Internet Protocol. Simultaneously, service providers are deploying Ethernet to exploit the demand for wide-area Ethernet services and as the infrastructure for new residential services. such as IPTV. This is due to Ethernet's low cost per bit and ubiquity in local area networks. Recent years have seen the widespread deployment of IP/MPLS networks to address this opportunity. IP/MPLS enables enhanced flexibility over the same converged network for IP and legacy services, avoiding the need to build separate per-service networks. It also adds carrier-grade capabilities such as quality of service, traffic engineering, and resiliency, thereby enabling new multipoint services such as virtual private LAN service. However, using Ethernet for "always-on" and other mission-critical services has resulted in new resiliency requirements, in both the access and the network core. Two novel developments address these high expectations by enabling significant improvements in service availability. These are pseudowire redundancy and Ethernet multi-chassis link aggregation. This article reviews the current redundancy mechanisms typically deployed in Ethernet and MPLS networks. We show how additional enhancements are required in both the network core and the access to the Ethernet service. We describe new pseudowire redundancy and MC-LAG mechanisms, showing how they work together to enable end-to-end protection for Ethernet virtual private wire services and VPLS. [ABSTRACT FROM AUTHOR]

Covert channels are used for the secret transfer of information. Encryption only protects communication from being decoded by unauthorized parties, whereas covert channels aim to hide the very existence of the communication. Initially, covert channels were identified as a security threat on monolithic systems such as mainframes. More recently, focus has shifted toward covert channels in computer network protocols. The huge amount of data and large number of different protocols in the Internet is ideal as a high-bandwidth vehicle for covert communication. This article provides an overview of the existing techniques for creating covert channels in widely deployed network protocols, and common methods for their detection, elimination, and capacity limitation. [ABSTRACT FROM AUTHOR]

In this article, a new Internet broadcasting scheme that combines the existing network-wide unicast protocol and a subnet-wide broadcast protocol is proposed. The proposed broadcasting scheme is appropriate for location-based push services and requires only a minor functional addition to the existing edge routers, base stations, or access points. To eliminate unnecessary broadcasting traffic, an efficient terminal-originated triggering algorithm for broadcast initiation is introduced. The scheme provides location-based information to mobile users without the need for protocol reconfigurations or prior knowledge of a user's location. We also discuss some potential applications of the scheme. Performance of the proposed scheme has been evaluated and selected results are presented in this article. The evaluation shows that the broadcasting scheme significantly reduces the network traffic and the server load. [ABSTRACT FROM AUTHOR]

Giving the operator the ability to manage in-home devices greatly increases the potential of the cost-efficient provision of new profitable services. In this spirit, standardization undertaken by the DSL forum not only addresses remote management of the residential gateway but recently, also extends to in-house devices. We propose a solution that bridges remote management specified by CWMP with UPnP, already established inside the home environment. This approach will enable providers to remotely configure and manage in-house UPnP-enabled equipment, thus accelerating the deployment of new services. We investigate the nature of the two protocols and specify the bridging functionality, taking into consideration scalability and transparency. Experimental results support the applicability of the proposed approach, highlight the importance of message filtering, and provide general insight into the interplay intricacies of the particular protocol functions. [ABSTRACT FROM AUTHOR]

As communications networks become increasingly dynamic, heterogeneous, less reliable, and larger in scale, it becomes difficult, if not impossible, to effectively manage these networks using traditional approaches that rely on human monitoring and intervention to ensure they operate within desired bounds. Researchers and practitioners are pursuing the vision of autonomic network management, which we view as the capability of network entities to self-govern their behavior within the constraints of business goals that the network as a whole seeks to achieve. However, applying autonomic principles to network management is challenging for a number of reasons, including: • A means is required to enable business rules to determine the set of resources and/or services to be provided. • Contextual changes in the network must be sensed and interpreted, because new management policies may be required when context changes. • As context changes, it may be necessary to adapt the management control loops that are used to ensure that system functionality adapts to meet changing user requirements, business goals, and environmental conditions. • A means is required to verify modeled data and to add new data dynamically so that the system can learn and reason about itself and its environment. This article provides an introduction to the FOCALE autonomic network management architecture, which is designed to address these challenges. [ABSTRACT FROM AUTHOR]

The home gateway market is undergoing deep changes. On one side, home networks are evolving, getting dynamic and federating more and more devices. On the WAN side, new actors appear, such as multimedia content providers. From both sides emerge new features and new management needs. In this article we highlight challenges and benefits of moving more intelligence to the home gateway, making it more than a simple interconnection device. We argue that we need a full-fledged execution environment on gateways to address the evolution of business models. We present this evolution and summarize existing solutions for execution environments and management for home gateways. Then we propose two improvements that reflect the new requirements. The first improvement is a high-level virtualization of service gateways, and the second one recommends an end-to-end dynamic multiprovider management system. [ABSTRACT FROM AUTHOR]

Although network management has always played a key role for industry, it only recently received a similar level of attention from many research communities, accelerated by funding opportunities from new initiatives, including the FP7 Program in Europe and GENI/FIND in the United States. Work is ongoing to assess the state of the art and identify the challenges for future research in the field, and this article contributes to this discussion. It presents major findings from a two-day workshop organized jointly by the IRTF/NMRG and the EMANICS Network of Excellence, at which researchers, operators, vendors, and technology developers discussed the research directions to be pursued over the next five years. The workshop identified several topic areas, including management architectures, distributed real-time monitoring, data analysis and visualization, ontologies, economic aspects of management, uncertainty and probabilistic approaches, as well as understanding the behavior of managed systems. [ABSTRACT FROM AUTHOR]

For label switched networks, such as MPLS and GMPLS, most existing traffic engineering solutions work in a single routing domain. These solutions do not work when a route from the ingress node to the egress node leaves the routing area or autonomous system of the ingress node. In such cases, the path computation problem becomes complicated because of the unavailability of the complete routing information throughout the network. This is because service providers usually choose not to leak routing information beyond the routing area or AS for scalability constraints and confidentiality concerns. This article serves two purposes. First, it provides a description of the existing and ongoing work in interdomain TE within the IETF. This information is currently found in various Internet drafts and has not yet been collectively presented in a single document. To this end, a summary of both existing path computation architectures — PCE-based and per-domain — is provided. Second, it compares two per-domain path computation schemes in terms of the total number of LSPs successfully placed and average number of domains crossed, without assuming availability of complete topology information. We notice that the two per-domain path computation schemes, proposed in [1, 2], have comparable path computation complexities and setup latencies. [ABSTRACT FROM AUTHOR]

Automatic resource discovery plays a significant role in next-generation optical networks, where nodes can maintain a large number of input/output ports (fibers, wavelengths, time slots, etc.). This automation avoids long and tedious manual node configurations and minimizes resource misconfiguration probability, which can result in high cost savings for network operators. The generalized multiprotocol label sswitching (GMPLS) Link Management Protocol (LMP) has been defined to provide such functionalities. However, it requires optical nodes to transmit in-band information, thus requesting link termination on each incoming port. This issue, in transparent optical networks, implies additional hardware, high complexities, or even signal losses. This article proposes and evaluates novel extensions to standard LMP that cope with the discovery of all-optical transport planes. In addition, playing a crucial role in ASON/GMPLS networks, this article also generically covers the automatic discovery of the control plane. [ABSTRACT FROM AUTHOR]