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To solve the inefficient use of internet protocol (IP) addresses in the current host‐centric internet, the content‐centric networking (CCN) replaces the IP address with the content name and the cache memory is used to store data temporarily on each router. One of the key components in CCN is the pending interest table (PIT). When an interest arrives at a CCN node, the node searches the PIT entries for the same request. If no, the node searches the PIT for an idle entry and a request is sent. If there is no idle entry, the request is blocked. If yes, the aggregation mechanism is performed. To prevent the request from becoming out‐of‐date, the timeout mechanism is adopted. In this work, the authors focus on the performance analysis of PIT in the cellular network with two classes of interests, new and handoff interests. To provide service differentiation, a reservation mechanism is adopted. Furthermore, interests may enter the retrial queue and wait to retry later. First, the authors derived the analytical model for the system considered. Second, the impact of various system parameters on the performance measures is studied. Last but not least, computer simulation is written to verify the accuracy of the analytical results. [ABSTRACT FROM AUTHOR]

Deep packet inspection (DPI) acts as a tool to control and classify incoming network traffic depending on users,content, applications and becomes a very important aspect of every network today. Instead of utilising only incoming packet header information, Internet service providers utilise DPI for security purposes, flow management, and routing. The high‐performance challenges that face DPI techniques to manage line‐speed packet processing with restricted available memory are the increasing traffic volumes and link rates. Bloom (BF) and quotient (QF) filters are effective randomised data structures for performing approximate membership queries. They have been employed in many networking applications including DPI. Nevertheless, they consume more calculations which degrade the system performance. Consequently, in this paper, the authors propose a new variant of membership query data structure, called quotient‐based Cuckoo filter (QCF), that reflects a merging process between QF and CF to minimise the calculation overhead and employing it in a DPI system. QCF employs only two hash functions and consumes less calculation overhead than BF, QF, and CF. The implementation results show that using QCF as an identification tool in a DPI system result in a time improvement up to 77% over CF and up to 98% over BF and QF. [ABSTRACT FROM AUTHOR]

Internet router buffers are commonly made very large with the aim of minimising losses and maximising link utilisation, supported by the ever‐decreasing cost of memory. However, large packet queues not only increase the energy consumption, but can also adversely affect network performance which has recently been attracting attention under 'bufferbloat'. This study compares the buffer‐related energy consumption of two models, that is, 'large‐buffer with on–off server' and 'small‐buffer with always‐on server' in the presence of multiplexed on–off traffic and FTP traffic; and demonstrates that the latter model is more energy efficient. Further analysis is then carried out on the 'small‐buffer model with always‐on server' for the evaluation of its performance against different levels of energy consumption. Relationships among energy, delay, throughput and loss are studied in a range of scenarios, quantifying the variations in performance metrics in relation to energy consumption. In general, lower buffer sizes which reduce the energy consumption were found to improve delay, but sacrifice throughput by 5–8% at high load. Based on a broad set of results, this study provides guidelines for sizing router buffers in realistic networks which would lead to optimal trade‐offs between energy consumption and quality of service. [ABSTRACT FROM AUTHOR]

The heavy tailed (HT) traffic from wireless users, caused by the emerging Internet and multimedia applications, introduces a HT interference region within which network users will experience unbounded delay with infinite mean and/or variance. Specifically, it is proven that, if the network traffic of primary networks (e.g., cellular and Wi-Fi networks) is heavy tail distributed, there always exists a critical density λp such that, if the density of primary users is larger than λp, the secondary network users (e.g., sensor devices and cognitive radio users) can experience unbounded end-to-end delay with infinite variance even though there exists feasible routing paths along the network users. To counter this problem, the mobility of network users is utilized to achieve delay-bounded connectivity, which simultaneously ensures the existence of routing paths and the finiteness of the delay variance along these paths. In particular, it is shown that there exists a critical threshold on the maximum radius that the secondary user can reach, above which delay-bounded connectivity is achievable in the secondary networks. In this case, the end-to-end latency of secondary users is shown to be asymptotically linear in the Euclidean distance between the transmitter and receiver. [ABSTRACT FROM PUBLISHER]

Although nowadays Internet is facing more and more threats, very few works have investigated the security situation assessment for inter‐domain routing system which is the most significant infrastructure of Internet. To deal with the problem, a situation assessment model based on the immune Danger Theory is proposed. In this study, the authors first give a comprehensive description of the model architecture as well as practical considerations, and then the main components including signal mapping, antigen selection, routing behaviour analysis and global situation assessment are, respectively, defined and illustrated. Evaluations are launched in view of Japan earthquake and YouTube hijacking, and the results show that the model is able to assess the global anomalous degree of specific inter‐domain routing system quantitatively, which can provide network administrator with accurate and timely information to conduct network monitoring and route protection. [ABSTRACT FROM AUTHOR]

Internet traffic at various tiers of service providers is essentially a superposition or active mixture of traffic from various sources. Statistical properties of this superposition and a resulting phenomenon of scaling are important for network performance (queuing), traffic engineering (routing) and network dimensioning (bandwidth provisioning). In this article, the authors study the process of superposition and scaling jointly in a non‐asymptotic framework so as to better understand the point process nature of cumulative input traffic process arriving at telecommunication devices (e.g., switches, routers). The authors further assess the scaling dynamics of the structural components (packets, flows and sessions) of the cumulative input process and their relation with superposition of point processes. Classical and new results are discussed with their applicability in access and core networks. The authors propose that renewal theory‐based approximate point process models, that is, Pareto renewal process superposition and Weibull renewal process superposition can model the similar second‐order scaling, as observed in traffic data of access and backbone core networks, respectively. [ABSTRACT FROM AUTHOR]

Transmission control protocols (TCPs) are used to control the congestion in the Internet. Various types of TCP protocols have been proposed including TCP Reno, TCP Tahoe and TCP Vegas. Although TCP Reno is widely used for wired communications, TCP Vegas is proved to have better performance in wireless environments. In TCP Reno, to achieve a certain queue level at the intermediate routers, active queue management (AQM) schemes are used. An AQM scheme marks the packets at the intermediate routers and TCP Reno source uses that mark to adjust its speed. However, in TCP Vegas, such scheme is not useable. Consequently, the queue level adjustment is not achievable. A scheme which is employed at the source and adjusts the TCP Vegas parameters dynamically to achieve a certain queue level at the intermediate router is proposed. To the best of the knowledge, this is the first attempt to dynamically adjust the queue levels when TCP Vegas is employed. Our proposed scheme plays the role of AQM in TCP Reno for TCP Vegas. The control scheme presented is designed based on integral backstepping technique and will be applied to the linearised model of TCP Vegas. [ABSTRACT FROM AUTHOR]

Purpose – The publish/subscribe paradigm is useful for content diffusion in the internet. The purpose of this paper is to propose subscription covering to reduce the size of routeing table and notification matching time. Design/methodology/approach – The paper proposes a necessary and sufficient condition of correct routeing table configuration when using SSCBR algorithm. Findings – Experiments show that both SSCBR and RSCBR can reduce the size of routeing table, network traffic and time. Research limitations/implications – All these experiments are based on high speed wireline network. For wireless network, the results may be different. Originality/value – The paper proposes a necessary and sufficient condition of correct routeing table configuration when using SSCBR algorithm and can easily validate the correctness of brokers' routeing table through it. Because RSCBR calculates less subscription covering relation, its performance in network traffic and average notification processing time may be better than SSCBR in certain scenarios. [ABSTRACT FROM AUTHOR]

A wireless mesh network is a wired extension of a multihop ad hoc network that defines a new paradigm for broadband wireless Internet access. A packet originating from a mesh client is relayed collaboratively in a multihop fashion by the intermediate mesh routers toward an Internet gateway. All existing mesh routing protocols assume that each MR honestly participates in packet forwarding. This is valid only in a network managed by a single trusted authority. However, a community-based WMN can be formed by a group of independent MRs operated by different service providers. It is a real challenge to establish a priori trust in a multi-operator WMN. In such a situation, a selfish MR might be motivated to monopolize the wireless channel for itself by intentionally dropping others' packets. This results in severe performance degradation. Thus, enforcing collaboration is a determinant aspect in designing a secure and reliable WMN. In this article we analyze selfishness of MRs in a multi-operator WMN and explore its overall negative impact on network performance. We finally present a summary of various existing schemes with respect to detecting selfishness, analyze their usefulness in WMNs, and highlight their relative advantages and deficiencies. [ABSTRACT FROM PUBLISHER]

In recent years, the number of peer-to-peer (P2P) applications has increased significantly. One important problem in many P2P applications is how to efficiently disseminate data from a single source to multiple receivers on the Internet. A successful model used for analyzing this problem is a graph consisting of nodes and edges, with a capacity assigned to each edge. In some situations however, it is inconvenient to use this model. To that end, we propose to study the problem of efficient data dissemination in a source constraint network. A source constraint network is modeled as a graph in which, the capacity is associated with a node, rather than an edge. The contributions of this paper include (a) a quantitative data dissemination in any source constraint network, (b) a set of topologies suitable for data dissemination in P2P networks, and (c) an architecture and implementation of a P2P system based on the proposed optimal topologies. We will present the experimental results of our P2P system deployed on PlanetLab nodes demonstrating that our approach achieves near optimal throughput while providing scalability, low delay and bandwidth fairness among peers. [ABSTRACT FROM PUBLISHER]

The distributed denial-of-service (DDoS) attack is a serious threat to the legitimate use of the Internet. Prevention mechanisms are thwarted by the ability of attackers to forge or spoof the source addresses in IP packets. By employing IP spoofing, attackers can evade detection and put a substantial burden on the destination network for policing attack packets. In this paper, we propose an interdomain packet filter (IDPF) architecture that can mitigate the level of IP spoofing on the Internet. A key feature of our scheme is that it does not require global routing information. IDPFs are constructed from the information implicit in border gateway protocol (BGP) route updates and are deployed in network border routers. We establish the conditions under which the IDPF framework correctly works in that it does not discard packets with valid source addresses. Based on extensive simulation studies, we show that, even with partial deployment on the Internet, IDPFs can proactively limit the spoofing capability of attackers. In addition, they can help localize the origin of an attack packet to a small number of candidate networks. [ABSTRACT FROM PUBLISHER]

In today's practical communication networks such as the Internet, information delivery is performed by routing. A promising generalization of routing is network coding. The potential advantages of network coding over routing include resource (e.g., bandwidth and power) efficiency, computational efficiency, and robustness to network dynamics. This tutorial article provides an overview of the theory, practice, and applications of network coding. [ABSTRACT FROM PUBLISHER]

Public-access networks need to handle persistent congestion and overload caused by high bandwidth aggregates that may occur during times of flooding-based DDoS attacks or flash crowds. The often unpredictable nature of these two activities can severely degrade server performance. Legitimate user requests also suffer considerably when traffic from many different sources aggregates inside the network and causes congestion. This paper studies a family of algorithms that "proactively" protect a server from overload by installing rate throttles in a set of upstream routers. Based on an optimal control setting, we propose algorithms that achieve throttling in a distributed and fair manner by taking important performance metrics into consideration, such as minimizing overall load variations. Using ns-2 simulations, we show that our proposed algorithms 1) are highly adaptive by avoiding unnecessary parameter configuration, 2) provide max-min fairness for any number of throttling routers, 3) respond very quickly to network changes, 4) are extremely robust against extrinsic factors beyond the system control, and 5) are stable under given delay bounds. [ABSTRACT FROM PUBLISHER]

Several research studies have been devoted to improving the reliability and performance of the Internet by utilizing redundant communication paths between end points. Multihoming, coupled with intelligent route control, and overlay networks are two main streams in this area of research which attempt to leverage redundant connections of the Internet for increased reliability and performance. However, the effectiveness of these approaches depends on the natural diversity of redundant paths between two endhosts in terms of physical links, routing infrastructure, administrative control, and geographical distribution. Even in the case of redundant paths, if traffic between two hosts is not actually routed along completely disjoint paths, congestion or failure of a single shared link or router can adversely affect the end-to-end performance or availability of all paths. This paper presents an experimental study of path diversity on the Internet, focusing on the impact of path diversity on multihomed and overlay networks. We base our analysis on traceroutes and routing table data collected from several vantage points in the Internet including: looking glasses at 10 major Internet service providers (ISPs), RouteViews servers from 20 ISPs, and more than 50 PlanetLab nodes globally distributed across the Internet. Using this data, we quantify the extent of path diversity in multihoming and overlay networks, highlighting the limitations, and also identifying the source of the limitations in these architectures. From the analysis, we learn that both multihoming route control and current overlay networks are not able to ensure path diversity, which makes it very difficult to provide high-availability services even with the use of these systems. We believe that this work provides the insight into building future systems based on understanding path diversity [ABSTRACT FROM PUBLISHER]

Quality-of-service (QoS) routing between domains is an essential component for providing service differentiation in the Internet. State aggregation is a technique that makes QoS routing scalable to large internetworks, by presenting a concise and accurate representation of the domain to the routing process. The concept of using a domain's routing capacity as a bandwidth aggregate has been in existence for some time. However, no methodology has been suggested in the literature for its estimation and usage. Also, the impact of a domain's routing capacity on the routing performance has not been studied before. This paper aims to fill these voids by presenting a framework based on "network flows" for estimating a domain's routing capacity and evaluating its efficacy on the routing performance. The routing capacity is used in conjunction with the conventional widest path bandwidth as the domain aggregate. Analytical and experimental results show that appropriate use of routing capacity along with the widest path bandwidth reduces the tendency of the advertised aggregate to overestimate bandwidth availability, and makes the routing process more robust to the frequency of domain state updates. During periods of congestion, the use of routing capacity can improve the bandwidth admitted into the network by as much as 20% [ABSTRACT FROM PUBLISHER]

This paper presents the design and experimental implementation of an in-service performance monitoring system that uses a combination of non-intrusive spectral optical performance monitoring and Internet protocol (IP) metrics and is based on a low-complexity, distributed architecture. Apart from guaranteeing QoS in real time (less than 1 s) in an IP/wavelength-division-multiplexing (WDM) dynamic network, the system provides link-state information for impairment-aware routing and wavelength assignment. Another novel aspect is the nature of the service level agreements proposed, which are "all-optical" (transparent). Performance delays of the system are evaluated in a real test bed featuring dense WDM and transparent optical add-drop multiplexers. Strategies to estimate link-state parameters from real-time monitoring information are also proposed [ABSTRACT FROM PUBLISHER]

This paper reports on modern features of the optical-label switching (OLS) system in support of multicast, optical time-to-live (TTL), and video-streaming applications. We first propose and demonstrate optical-label switching core router architecture with multicast function. The multicast switching architecture provides reduced complexity and effective multicast contention resolution compared to conventional multicast-capable switching fabric. A proof-of-principle experiment successfully showed packet multicast forwarding with contention resolution. The all-optical TTL monitors the healthiness of the packet, and prevents degraded packets from traveling or looping further in the network. The experiment demonstrated successful packet discards based on optical signal-to-noise ratio degradation. Finally, we present an optical label switching edge router that supports aggregation, quality of service, and class of service, and we further demonstrate a video streaming application between Ethernet clients through the OLS edge routers and a core router. The modern features of OLS routers proposed and demonstrated in this paper indicate the viability of OLS technologies in future photonic Internet in support of modern applications. [ABSTRACT FROM PUBLISHER]

R&D activities on photonic networks in Japan are presented. First, milestones in current ongoing R&D programs supported by Japanese government agencies are introduced, including long-distance and wavelength division multiplexing (WDM) fiber transmission, wavelength routing, optical burst switching (OBS), and control-plane technology for IP backbone networks. Their goal was set to evolve a legacy telecommunications network to IP-over-WDM networks by introducing technologies for WDM and wavelength routing. We then discuss the perspectives of so-called PHASE II R&D programs for photonic networks over the next 5 years until 2010, by focusing on the report that has been recently issued by the Photonic Internet Forum (PIF), a consortium that has major carriers, telecom vendors, and Japanese academics as members. The PHASE II R&D programs should serve to establish a photonic platform to provide abundant bandwidth on demand, at any time on a real-time basis, through the customer's initiative to promote bandwidth-rich applications, such as grid computing, real-time digital-cinema streaming, medical and educational applications, and network storage in e-commerce. [ABSTRACT FROM PUBLISHER]

A fault-tolerant scheme, called dual homing, is generally used in IP-based access networks to increase the availability of the networks. In a dual-homing architecture, a host is connected to two different access routers; therefore, it is unlikely that the host will be denied access to the network as the result of an access line break, a defective power supply in the access router, or congestion of the access router. This dual-homing architecture in the access network imposes the overhead to provide protection in the core network. Scaling the next-generation IP-over-wavelength-division-multiplexing (WDM) Internet, and being able to support a growing number of such dual-homing connections, as well as protection, demands a scalable mechanism to contain this overhead for protection in the WDM networks. This paper studies the coordinated protection design to reduce the protection cost in the WDM core network, given a dual-homing infrastructure in the access network. The protection problem is considered for both static and dynamic traffic. Several solutions are proposed, and the performances of the solutions are compared. We also prove that one of the proposed algorithms gives a solution that, in the worst case, is at most 4/3 times the cost of the optimal solution. [ABSTRACT FROM PUBLISHER]

This paper presents the design and experimental implementation of a service-oriented Internet Protocol (IP)/wavelength division multiplexing (WDM) management plane. In the proposed approach, compliant with International Telecommunication Union Telecommunication Standardization Sector (ITU-T)'s automatic-switched optical network (ASON), a distributed control plane performs signaling, routing, and discovery functions, and a decentralized management plane, both at information and architectural levels, performs cross-plane actions to enforce service establishment and monitoring with a view to guarantee service level agreements (SLAs). In-service monitoring provides status of optical resources and services by using spectral- and time-domain information. Some performance aspects of the approach are evaluated in a real testbed featuring dense wavelength multiplexing and a control plane based on the Internet Engineering Task Force (IETF)'s generalized multiprotocol label switching (GMPLS). [ABSTRACT FROM PUBLISHER]

We propose a new optical switch that can enable wavelength-selective high-speed switching for applications to photonic wavelength-division multiplexing (WDM) Internet protocol (IP) packet routing. The switch utilizes characteristics of waveguide-type Raman amplifiers and 3-dB couplers, and so it operates all-optically at a few tens of picosecond or faster speed. The operation of the switch is studied by coupled-mode theory and is verified numerically using a beam-propagation method (BPM). As a result, we found that optical waves having arbitrary wavelengths among those of incident WDM waves are amplified and switched when the amplification rate of each waveguide-type Raman amplifier is set to the proper value by pump wave injection. Moreover, the dynamic range over 30 dB was also obtained from the simulation results of the switch. [ABSTRACT FROM PUBLISHER]

With the increased popularity of multimedia services on the Internet, efficient video multicast strategies that can scale easily are of critical importance. This paper addresses the issue of video multicast loss recovery and presents an efficient and scalable scheme: Active Injection Recovery (AIR). The proposed scheme has three distinguishing features: active injection of repair packets into loss regions, on-demand construction of loss-recovery structures, and unique rate control over repair traffic. All of these features can save considerable network resources in a large-scale video multicast session. In addition, the proposed scheme simultaneously meets the three well-known requirements for efficiency and scalability in multicast loss recovery: request suppression, local recovery, and retransmission scoping. Another important feature of the proposed scheme is its low recovery latency, which is essential for video multicast. Our results show that the proposed scheme achieves significantly better overall performance as compared to existing multicast loss recovery schemes. [ABSTRACT FROM PUBLISHER]

As new bandwidth-hungry Internet protocol (IP) services are demanding more and more capacity, transport networks are evolving to provide a reconfigurable optical layer in order to allow fast dynamic allocation of wavelength-division-multiplexing (WDM) channels. To achieve this goal, optical packet-switched systems seem to be strong candidates as they allow a high degree of statistical resource sharing, which leads to an efficient bandwidth utilization. In this paper, we propose an architecture for optical packet-switched transport networks, together with an innovative switching node structure based on the concept of per-packet wavelength routing. The traffic performance of such node when loaded by a typical IP traffic is evaluated through computer simulation; packet loss probability and average delay performance are shown for various load conditions. [ABSTRACT FROM PUBLISHER]

Optical networks have been extensively investigated in recent years to provide high capacity for the Internet traffic. Among them the optical packet-switching network deploying buffering, wavelength conversion and multipath routing could be the most suitable one. It cannot only provide high capacity transport for Internet traffic but also achieve high utilization of the network resources. However due to the packet-oriented routing and switching, such a network can result in a large amount of packets out-of-order, packet loss and/or with various delays upon arriving at end systems, causing TCP flows that comprise those packets corrupted. Large amount of corrupted flows can increase the burstiness of the Internet traffic and cause higher-layer protocol to malfunction. This paper presents a novel routing and switching method for optical IP networks-flow routing. Without using a complicate control mechanism flow routing deals with packet-flows to reduce the amount of corrupted flows. The performance of the wavelength-converted optical flow router is investigated, based on a novel analytical model. A performance metric, i.e., good-throughput, is used, measuring the ratio of the amount of packets comprised in the noncorrupted flows to total amount of packets. Comparing with optical packet-switching routers, a remarkable improvement of good-throughput can be obtained by using optical flow routers. More important, using wavelength conversion can greatly improve the good-throughput of optical flow routers. [ABSTRACT FROM PUBLISHER]

This paper presents both theoretical and experimental studies carried on wavelength-division multiplexing (WDM) networks with arbitrary (mesh) topology that provide optical circuits with differentiated reliability (DiR). Reliability is obtained by means of a modified shared path protection (SPP) switching scheme-here referred to as SPP-DiR. As explained in the paper, SPP-DiR networks provide multiple degrees of circuit reliability that satisfy client-specific reliability requirements in a cost-effective way. The theoretical study first defines the problem of optimally designing SPP-DiR WDM networks. It then presents a time-efficient suboptimal algorithm that determines the routing and the reliability degree of each demand in the given traffic matrix by applying both the conventional SPP and the SPP-DiR scheme. When compared to dedicated path protection switching, results obtained for the pan-European network using the proposed algorithm indicate cost reductions of about 16% when SPP is applied, and up to 34% when SPP-DiR is applied. The experimental study describes the Ω testbed-a WDM optical circuit-switched mesh network with an IP control plane-which is believed to be the first testbed ever built that makes use of the SPP-DiR scheme. Experimental results performed on the Ω testbed report restoration times of the optical circuits-disrupted by a fiber fault-that are few tens of milliseconds. [ABSTRACT FROM PUBLISHER]

We focus on DiffServ for QoS provisioning in radio access networks (RANs). We first give short explanations of the DiffServ model. We then investigate the problems of DiffServ under IP mobility environments. We also present several DiffServ proposals in IP-based access networks. We finally propose a mobility-aware drop precedence scheme for flows experiencing handover events. [ABSTRACT FROM PUBLISHER]

In the past few years, multimedia applications have become very popular on the Internet, and a growing number of users have shown interest in this type of communications. IP multicasting has logically been considered to support such transmissions, mainly because its inherent nature is to efficiently minimize the bandwidth required to deliver multimedia data to a large set of targeted receivers. In the meantime, there has been a steady increase in the number of mobile wireless devices connected to the Internet. It has also clearly appeared that mobile Internet users will expect to have access to the services and applications available in traditional wired networks, and these services will surely include multimedia applications. Consequently, many efforts are being made to provide efficient mobility and multicasting support, and to bring the two together in the next generation of IP networks. [ABSTRACT FROM PUBLISHER]

This paper proposes and analyzes a strategy for protection and restoration of optical paths in wavelength division multiplexing (WDM) networks for next-generation Internet infrastructure. Assuming a network model in which a multiprotocol label switching (MPLS) layer is overlaid on top of a WDM layer, and a segregation of the traffic on a wavelength basis, the strategy is based on a network dimensioning aiming at: 1) the support of different types of traffic, relating to different service categories; 2) the guarantee that all the wavelength paths carrying mission-critical services (with stringent quality of service requirements) are protected against failure; and 3) the possibility of restoring a large amount of wavelength paths carrying Internet best-effort services, i.e., low-priority (LP) preemptible traffic with no QoS requirements. The reference network scenario is an overlay model in which the optical network interacts with an MPLS network with a separated control plane; the optical network manages its resources to better serve the traffic coming from the MPLS network. Two path protection schemes, namely, disjoint path (DP) and single-link basis (SLB), and a link protection mechanism, namely, local repair (LP), are investigated. Furthermore, the paper considers both the case of using wavelength conversion in the optical nodes and the case in which wavelength conversion is not used at all. The analysis compares the performance of the different strategies in terms of the percentage of optical paths carrying LP traffic not served by the optical network after a failure and of the dimensions of the optical nodes for all the schemes. The analysis reveals that the proposed approach allows the restoration of a large amount of best-effort traffic with a reasonable increase of network redundancy. [ABSTRACT FROM PUBLISHER]

Adaptive and self-organizing wireless networks are gaining in popularity. Several media access and routing protocols were proposed for such networks and the performance of such protocols were evaluated based on simulations. In this paper, we evaluate the practicality of realizing an ad hoc wireless network and investigate on performance issues. Several mobile computers were enhanced with ad hoc routing capability and were deployed in an outdoor environment and communication performance associated with ad hoc communications were evaluated. These computers periodically send beacons to their neighbors to declare their presence. We examined the impact of varying packet size, beaconing interval, and route hop count on route discovery time, communication throughput, end-to-end delay, and packet loss. We had also performed mobility experiments and evaluated the route reconstruction time incurred. File transfer times associated with sending information reliably (via TCP) over multihop wireless links are also presented. The experimental results obtained revealed that it is feasible to augment existing wireless computers with ad hoc networking capability. End-to-end performance in ad hoc routes are less affected by beaconing intervals than packet size or route length. Similarly, communication throughput is more dependent on packet size and route length with the exception at very high beaconing frequencies. Packet loss, on the other hand, is not significantly affected by packet size, route length or beaconing frequency. Finally, route discovery time in ad hoc wireless networks are more dependent on channel conditions and route length than variations in beaconing intervals [ABSTRACT FROM PUBLISHER]

Today's Internet is a massive, distributed network which continues to explode in size as e-commerce and related activities grow. The heterogeneous and largely unregulated structure of the Internet renders tasks such as dynamic routing, optimized service provision, service-level verification, and detection of anomalous/malicious behavior increasingly challenging tasks. The problem is compounded by the fact that one cannot rely on the cooperation of individual servers and routers to aid in the collection of network traffic measurements vital for these tasks. In many ways, network monitoring and inference problems bear a strong resemblance to other "inverse problems" in which key aspects of a system are not directly observable. Familiar signal processing problems such as tomographic image reconstruction, system identification, and array processing all have interesting interpretations in the networking context. This article introduces the new field of network tomography, a field which we believe will benefit greatly from the wealth of signal processing theory and algorithms [ABSTRACT FROM PUBLISHER]

We present a performance comparison of a number of key micromobility protocols that have been discussed in the IETF Mobile IP Working Group over the past several years. IP micromobility protocols complement Mobile IP by offering fast and seamless handoff control in limited geographical areas, and IP paging in support of scalability and power conservation. We show that despite the apparent differences between IP micromobility protocols, the operational principles that govern them are largely similar. We use this observation to establish a generic micromobility model to better understand design and performance trade offs. A number of key design choices are identified within the context of the generic model related to handoff quality and route control messaging. We present simulation results for Cellular IP, Hawaii, and Hierarchical Mobile IP, and evaluate the handoff performance of these protocols. Simulation results presented in this article are based on the Columbia IP Micromobility Software (CIMS), which is freely available from the Web (comet.columbia. edu/micromobility) for experimentation. [ABSTRACT FROM PUBLISHER]

NASA is interested in applying Mobile Internet Protocol (mobile-IP) technologies to its space and aeronautics programs. In particular, mobile-IP will play a major role in the Advanced Aeronautic Transportation Technology (AATT), the Weather Information Communication (WINCOMM) and the Small Aircraft Transportation System; (SATS) aeronautics programs. This paper describes mobile-IP and mobile-routers-in particular, the features, capabilities, and initial performance of the mobile-router is presented. The application of mobile-router technology to NASA's space and aeronautics programs is also discussed [ABSTRACT FROM PUBLISHER]

This article describes a network platform with future IP-based techniques for “beyond IMT-2000.” First, it presents a vision for beyond IMT-2000 in terms of requirements for service and network capabilities. Next, it shows a general architecture of the IP-based IMT network platform (IP2). Then it discusses the study of key network techniques (location management, routing/handover, and service management) featured in the proposed platform architecture [ABSTRACT FROM PUBLISHER]

This paper presents a new technology for constructing IP over photonic systems. An IP with multiprotocol label switching (MPLS) over wavelength division multiplexing (WDM)-based broad-band IP network architecture and protocol is proposed and analyzed in this paper, which supports variable-length IP-like optical packet label switching and optical virtual path routing. This system tries to merge into one layer the functionalities of the wavelength switching, SONET mux/demux, and IP routing, and is sometimes known as the concept of optical MPLS. The label banding, forwarding/switching process, and node architecture of the proposed network are discussed and studied. A unique as well as important function of a lambda/label edge router (LER) is a flow assembly device that can encompass MPLS' forward equivalence classes, label stacking, and label switching path aggregation function. At the same time, a particular function of the core label switching router is wavelength merging. A fiber delay line is used to delay the data stream in order to process the label information and resolve contention. Transmission bit error rate measurements of the baseband data stream and back-to-back is also demonstrated to show its feasibility [ABSTRACT FROM PUBLISHER]

This paper proposes an architecture for routing Internet protocol (IP) packets directly on optical networks. The use of label switching is assumed in the IP routers, while a new routing architecture is introduced to transport IP packets across an optical backbone network. The architecture is based on a two-tier multiplexing approach with wavelength division multiplexing (WDM) addressing the number of regional exchanges and time-division switching communicating among the hubs. Such an architecture not only has the advantages of simple network management and high efficiency with low latency; it also is scalable by addition of regional exchanges, hubs, and fibers [ABSTRACT FROM PUBLISHER]

This article describes our experiences building a multihop wireless ad hoc network of eight nodes driving around a 700 m by 300 m site. Each node runs the dynamic source routing protocol and interfaces seamlessly with existing Internet infrastructure and the Mobile IP protocol. We present quantitative results from data collected during runs of our testbed under a composite workload including voice, bulk data, and real-time data. Based on careful analysis of our data, we highlight radio propagation issues that network protocols will need to address in the future [ABSTRACT FROM PUBLISHER]

As data traffic increases exponentially in the Internet, a need of deploying ATM switches or IP routers with terabit/s capacity is emerging. By taking advantage of the advanced wavelength division multiplexing (WDM) technology, we propose a nonblocking WDM-based optical interconnection network (OIN) to interconnect multiple electronic router modules (RMs), where packets are stored and processed. The proposed architecture uses an input-output buffering scheme, where the OIN operates at twice the line rates to alleviate the head-of-line blocking and thus achieves close to 100% throughput. The OIN is capable of performing multicasting using the method of broadcast and select. Output port contention among the input packets is resolved by a novel ping-pong arbitration (PPA) scheme. For a 256-input packet switch, the arbitration can be completed within 11 gates delay, less than 5 ns using the current CMOS technology. We analyze the complexity of the OIN in optical components and interconnections, its power budget, and crosstalk caused by the finite ON-OFF ratio of optical switching gates. Bit error rates with respect to different ON-OFF ratios and extinction ratios are evaluated by simulations. The result shows that it is feasible to construct a 256×256 OIN with existing technology [ABSTRACT FROM PUBLISHER]

All-optical label swapping is a promising approach to ultra-high packet-rate routing and forwarding directly in the optical layer. In this paper, we review results of the DARPA Next Generation Internet program in all-optical label swapping at University of California at Santa Barbara (UCSB). We describe the overall network approach to encapsulate packets with optical labels and process forwarding and routing functions independent of packer bit rate and format. Various approaches to label coding using serial and subcarrier multiplexing addressing and the associated techniques for label erasure and rewriting, packet regeneration and packet-rate wavelength conversion are reviewed. These functions have been implemented using both fiber and semiconductor-based technologies and the ongoing effort at UCSB to integrate these functions is reported. We described experimental results for various components and label swapping functions and demonstration of 40 Gb/s optical label swapping. The advantages and disadvantages of using the various coding techniques and implementation technologies are discussed [ABSTRACT FROM PUBLISHER]

This paper overviews network design issues of the photonic transport network (PTN), which employs wavelength division multiplexing (WDM) and wavelength routing. The design issues are considered on the level of newly created high-speed transmission access paths, i.e., optical paths (OPs). These include the routing and wavelength assignment (RWA) problems involved in making the best use of network resources such as wavelengths and fibers. With this objective, design issues for ring and meshed type PTN are addressed by presenting the results of case studies in which existing heuristic RWA algorithms were employed. By utilizing the design tools, the possible network scale is then estimated, while considering state-of-the-art hardware realization technologies. Further consideration is given assuming an environment where PTN serves as a high-speed IP-backbone. An extensive case study shows the cost-effectiveness of IP-over-PTN over other scenarios such as IP-over-(point-to-point) WDM [ABSTRACT FROM PUBLISHER]

As wavelength division multiplexing (WDM) technology matures and multicast applications become increasingly popular, supporting multicast at the WDM layer becomes an important and yet challenging topic. In this paper, we study constrained multicast routing in WDM networks with sparse light splitting, i.e., where some switches are incapable of splitting light (of copying data in the optical domain) due to evolutional and/or economical reasons. Specifically, we propose four WDM multicast routing algorithms, namely, re-route-to-source, re-route-to-any, member-first, and member-only. Given the network topology, multicast membership information, and light splitting capability of the switches, these algorithms construct a source-based multicast “light-forest” (consisting one or more multicast trees) for each multicast session. While the first two algorithms can build on a multicast tree constructed by IP (which does not take into consideration the splitting capability of the WDM switches), the last two algorithms attempt to address the joint problem of optimal multicast routing and sparse splitting in WDM networks. The performance of these algorithms are compared in terms of the average number of wavelengths used per forest (or multicast session), average number of branches involved (bandwidth) per forest as well as average number of hops encountered (delay) from a multicast source to a multicast member. The results obtained from this research should present new and exciting opportunities for further theoretical as well as experimental work [ABSTRACT FROM PUBLISHER]

With the Internet protocol (IP) being the dominant protocol for new network services, there is increasing pressure to optimize the network infrastructure and protocols for IP traffic. We have designed a network architecture where each node integrates a router and an optical layer cross connect to create a router optimized for the optical Internet. IP is responsible for all networking functions including network optimality and packet and optical resource management, but delegates transmission work to the optical layer, exploiting the capacity of the optical layer cross-connects. While all control and signaling uses IP, the optical lightpaths may carry arbitrary traffic, and so the control applies as well to non-IP traffic [ABSTRACT FROM PUBLISHER]

A photonic label switching router (PLSR) of which the photonic label processing is based upon optical code correlation, is investigated. To resolve the electronic router's bottleneck in current Internet protocol (IP) over wavelength division multiplexing (WDM) networks, we will envision IP over photonic networks in which the PLSRs totally replace the electronic routers. The architectures of PLSR including the photonic label processing, the photonic label swapping, and the optical switching and their optical implementations are studied. Results of proof-of-concept experiments for the photonic label processing and photonic label swapping will confirm the feasibility to attain the target performance: the throughput of 100 Tb/s at least, the processing speed around 10 Gpacket/s, and the number of label entries up to 10 k [ABSTRACT FROM PUBLISHER]

Next generation internet optical network for regional access using multi-wavelength protocols (NGI ONRAMP) is a pre-competitive consortium sponsored by DARPA. Its mission is to develop architectures, protocols, and algorithms for wavelength division multiplexing (WDM)-based regional access networks that will effectively support the NGI. A reconfigurable WDM test bed is being built to demonstrate some of the key thrusts of the consortium, including dynamic service provisioning and optical flow switching, service protection in the optical domain, medium access control protocols, and network control and management geared for the efficient transport of Internet traffic over WDM networks. The ONRAMP test bed will consist of a feeder network connecting via access nodes to distribution networks on which the end users reside. ONRAMP network reconfiguration is enabled by access nodes that contain both optical and electronic switching components, allowing data traffic to be routed all-optically through the network or to be switched and aggregated by electronic Internet protocol (IP) routers. This paper describes the goals and basic architecture of the ONRAMP test bed, as well as the design, construction, and characterization of the network access nodes. To illustrate test bed operation, we demonstrate optical flow switching over the test bed that achieves Gb/s throughput of TCP data between end user workstations [ABSTRACT FROM PUBLISHER]

Wireless access to Internet services will become typical, rather than the exception as it is today. Such a vision presents great demands on mobile networks. Mobile IP represents a simple and scalable global mobility solution but lacks the support for fast handoff control and paging found in cellular telephony networks. In contrast, second- and third-generation cellular systems offer seamless mobility support but are built on complex and costly connection-oriented networking infrastructure that lacks the inherent flexibility, robustness, and scalability found in IP networks. In this article we present cellular IP, a micro-mobility protocol that provides seamless mobility support in limited geographical areas. Cellular IP, which incorporates a number of important cellular system design principles such as paging in support of passive connectivity, is built on a foundation of IP forwarding, minimal signaling, and soft-state location management. We discuss the design, implementation, and evaluation of a cellular IP testbed developed at Columbia University over the past several years. Built on a simple, low-cost, plug-and-play systems paradigm, cellular IP software enables the construction of arbitrary-sized access networks scaling from picocellular to metropolitan area networks [ABSTRACT FROM PUBLISHER]

One of the major objectives of third-generation mobile communications systems (TGMS) is the seamless integration of advanced multimedia services over both fixed and mobile networks leading to fixed-mobile convergence. Such systems will support audio, video, multimedia, data, and speech services in a variety of environments with levels of service for mobile users comparable to service currently available for fixed users. To achieve this, TGMS systems must provide adequate performance (in terms of bits per second) for each user in each of the operating environments foreseen. Despite considerable support from many sources (academia, network equipment manufacturers) the homogeneous network architecture that universal adoption of ATM would have provided seems unlikely to become a reality. The very rapid development of ultra-high-speed members of the Ethernet “family” has pre-empted the unique scalability promise of ATM. At the same time, the explosive growth of Internet-based applications and services has ensured that IP will remain the network layer protocol of choice for the vast majority of next-generation systems. This article examines the challenges of handover across a single network domain, between network domains, and specifically between network domains of different levels of QoS. We report on various techniques for supporting mobile terminals, different approaches to handover, and specific issues associated with TCP/IP over wireless links. Finally, we identify some of the more advanced mobile systems R&D projects from the “seamless integration of advanced multimedia services” perspective before generating our conclusions [ABSTRACT FROM PUBLISHER]

Active networks are a novel approach to network architecture in which the switches (or routers) of the network perform customized computations on the messages flowing through them. This approach is motivated by both lead user applications, which perform user-driven computation at nodes within the network today, and the emergence of mobile code technologies that make dynamic network service innovation attainable. The authors discuss two approaches to the realization of active networks and provide a snapshot of the current research issues and activities. They illustrate how the routers of an IP network could be augmented to perform such customized processing on the datagrams flowing through them. These active routers could also interoperate with legacy routers, which transparently forward datagrams in the traditional manner. [ABSTRACT FROM PUBLISHER]