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Network Mobility (NEMO) is concerned with managing the mobility of an entire network and included one or more Mobile Routers (MRs) which are connected as gateways to the Internet. This paper proposes the optimal handoff decision mechanisms, not only avoiding the ‘ping-pong effect' and frequent handoffs, but also reducing handoff latency under multi-hop network mobility. The simulation results demonstrate that the proposed method is well adapted for supporting network mobility over traditional handoff decision algorithms. [ABSTRACT FROM AUTHOR]

We study the throughput of multi-hop routes and stability of forwarding queues in a wireless Ad-Hoc network with random access channel. We focuse on wireless with stationary nodes, such as community wireless networks. Our main result is charactrerization of stability condition and the end-to-end throughput using the balance. We also investigate the impact of routing on end-to-end throughput and stability of intermediate nodes. We find that i) as long as the intermediate queues in the network are stable, the end-to-end throughput of a connection does not depend on the load on the intermediate nodes, ii) we showed that if the weight of a link originating from a node is set to the number of neighbors of this node, then shortest path routing maximizes the minimum probability of end-to-end packet delivery in a network of weighted fair queues with coupled servers. Numerical results are given and support the results of the analysis. [ABSTRACT FROM AUTHOR]

In this paper, we present an energy-efficient on-line diagnosis algorithm for cluster-based wireless sensor networks. It employs local comparisons of sensed data and dissemination of the decision made by the comparison results. Cluster-heads act as checkers for their associated cluster members. Redundant sensor nodes, as far as sensing coverage is concerned, are partially utilized to tolerate misbehavior of cluster-heads. Final decision on the fault status of sensor nodes is made at the base station. Computer simulation shows that high fault coverage can be achieved for a wide range of fault rates. [ABSTRACT FROM AUTHOR]

In order to support the sink mobility of conventional routing protocols, we propose a simple route maintaining algorithm which does not use the flooding method. In the proposed method, when the sink loses the connection with the source, it does not rebuild an entire route but simply repairs the existing route based on local information. Experimental results show that the proposed algorithm drastically improves the conventional routing protocols in terms of both energy and delay in case of mobile sink. [ABSTRACT FROM AUTHOR]

With IEEE 802.1S Multiple Spanning Tree Protocol, an Ethernet operator can define different network regions. A Common Spanning Tree (CST) is defined in such a way that a link failure inside a region does not affect the CST outside the region and additional Spanning Trees inside each region can be configured to achieve better load balance. We propose a procedure to determine the MSTP parameters configuration with multiple regions that optimize load balance and show its efficiency through computational results. We compare multiple region solutions with single region solutions, using a previous work on the single region case, and show that the multiple regions approach is better when traffic is mainly between switches belonging to the same region. [ABSTRACT FROM AUTHOR]

We introduce A-GAP, a protocol for continuous monitoring of network state variables with configurable accuracy. Network state variables are computed from device counters using aggregation functions, such as SUM, AVERAGE and MAX. In A-GAP, the accuracy is expressed in terms of the average error and is controlled by dynamically configuring filters in the management nodes. The protocol follows the push approach to monitoring and uses the concept of incremental aggregation on a self-stabilizing spanning tree. A-GAP is decentralized and asynchronous to achieve robustness and scalability. We provide some results from evaluating the protocol for an ISP topology (Abovenet) in several scenarios through simulation. The results show that we can effectively control the fundamental trade-off between accuracy and overhead. The protocol overhead can be reduced significantly by allowing only small error objectives. [ABSTRACT FROM AUTHOR]

The burst contention problem in Optical Burst Switching network is an intrinsically serious problem. Many researches have tried to solve this problem, however it have been known that avoiding the burst loss is very difficult issues in the current OBS network. To improve burst blocking rate, we consider the edge/core combined OBS network where the core node performs the edge node function as well. Through this architecture, available amount of data burst that the node generates can be expected with respect to offset-time of transit data bursts. Any researches for this area has not been performed, thus we propose a new data scheduling algorithm for the edge/core combined OBS network where data bursts that the node generates do not interrupt transit data bursts from previous nodes. We analyzed the data burst loss rate and the throughput in relation with the offset-time of transit data bursts. Results show that the loss rate of the data bursts is drastically reduced and the throughput improves when the offset-time of transit data bursts increases. Keywords: OBS, JET, scheduling, void filling, CoS. [ABSTRACT FROM AUTHOR]

Network clustering can facilitate data discovery and peer-lookup in peer-to-peer systems. In this paper, we design a distributed network clustering protocol, called SCM-based Distributed Clustering (SDC), for peer-to-peer networks. In this protocol, clustering is dynamically adjusted based on Scaled Coverage Measure (SCM), a practical clustering accuracy measure. By exchanging messages with neighbors, peers can dynamically join or leave a cluster so that the clustering accuracy of the whole network is improved. SDC is a fully distributed protocol which requires only neighbor information, and it can handle node dynamics locally with very small message overhead while keeping good quality of clustering. Through extensive simulations, we demonstrate that SDC can discover good quality clusters very efficiently. [ABSTRACT FROM AUTHOR]

This paper investigates the issue of enabling scalable quantitative delay guarantee support in DiffServ networks through NSIS. A NSIS QoS Model is utilized to add the admission control framework to the DiffServ architecture and reservation-based admission control algorithms are designed for ingress and interior nodes respectively for enabling quantitative delay guarantees in a DiffServ domain. Due to the NSIS protocol suite can support aggregate reservations effectively and the admission control algorithms are distributed at the ingress and interior nodes, our approach can enable the quantitative end-to-end delay guarantees in a DiffServ domain while still maintaining its simplicity and scalability. [ABSTRACT FROM AUTHOR]

In this paper, an equivalent model for the hybrid automatic retransmission request (HARQ) multi-input multi-output (MIMO) systems with a proper combining scheme is first introduced. Based on this effective model, we present a simple technique, termed antenna permutation scheme (APS), which permutates the transmit antennas at each retransmission to improve the diversity gain from retransmissions in the slow fading environment. The theory analysis and simulation results demonstrate that the system with APS can achieve much better bit error performance. Keywords: Hybrid ARQ, MIMO, V-BLAST, APS. [ABSTRACT FROM AUTHOR]

In this paper, we tackle one fundamental problem in Underwater Sensor Networks (UWSNs): robust, scalable and energy efficient routing. UWSNs are significantly different from terrestrial sensor networks in the following aspects: low bandwidth, high latency, node float mobility (resulting in high network dynamics), high error probability, and 3-dimensional space. These new features bring many challenges to the network protocol design of UWSNs. In this paper, we propose a novel routing protocol, called vector-based forwarding (VBF), to provide robust, scalable and energy efficient routing. VBF is essentially a position-based routing approach: nodes close to the "vector" from the source to the destination will forward the message. In this way, only a small fraction of the nodes are involved in routing. VBF also adopts a localized and distributed self-adaptation algorithm which allows nodes to weigh the benefit of forwarding packets and thus reduce energy consumption by discarding the low benefit packets. Through simulation experiments, we show the promising performance of VBF. [ABSTRACT FROM AUTHOR]

A wireless sensor network may consist of a large number of small, battery-powered, wireless sensor nodes and works in an unattended way. In order to manage the sensor network and collect data from the network efficiently, we need to know the state of the WSN. In this paper, we propose a model-aided approach to support the monitoring of the state of WSNs. In this approach, models are created on base station to support the monitoring of the network, and mobile agents are injected into the network to collect state information. Experimental results show the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

Flow measurement evolved into the primary method for measuring the composition of Internet traffic. Cisco's NetFlow is a widely deployed flow measurement solution that uses a configurable static sampling rate to control processor and memory usage on the router and the amount of reporting flow records generated. But during flooding attacks the memory and network bandwidth consumed by flow records can increase beyond what is available. In this paper, we propose an entropy based flow aggregation algorithm, which not only alleviates the problem in memory and export bandwidth, but also maximizes the accuracy of legitimate flows. Relying on information-theoretic techniques, the algorithm efficiently identifies the clusters of attack flows in real time and aggregates those large number of short attack flows to a few metaflows. Finally, we evaluate our system using real trace files from the Internet. [ABSTRACT FROM AUTHOR]

The routing protocols in use today operate on implicit trust among the different routers. Specifically, the distance vector routing (DVR) protocols compute routing tables in a distributed manner, based on this implicit trust. This trust model however fails to ensure the factual correctness of the routing updates, which is very critical for secure routing. We propose a neighbor update propagation model to ensure factual correctness and detect malicious activity by any subverted router. We also propose a secure DVR protocol based on this model using simple cryptographic primitives, and with minimal operational overhead. [ABSTRACT FROM AUTHOR]

We propose a novel resource allocation scheme, which can reduce MAP overhead and maximize the throughput in the MIMO-OFDM systems. In the message based broadband access system, we need to minimize the MAP overhead since the excessive MAP overhead causes degradation of system throughput. Increasing the size of resource allocation unit can reduce MAP overhead. However, multiuser diversity gain becomes smaller as the size of re-source allocation unit increases. Therefore, we investigate joint optimization between multiuser diversity gain and MAP overhead size. Using the proposed scheme, we can reduce MAP overhead size as well as achieve high throughput. [ABSTRACT FROM AUTHOR]

In the ITU-T ASON architecture, the control plane is responsible for providing intelligence to the network. The GMPLS paradigm pleads for a separation between the control plane and the forwarding plane. If the control plane is deployed disjoint from the forwarding plane, recovery mechanisms to ensure its proper operation are required. In this paper, on one hand, a quasi-associated mode backup control channel proposal is compared with a traditional associated 1:1 protection. On the other hand, extensions to LMP defined by the IETF are presented and evaluated to address both control channel and nodal failure recovery. The merits of the proposals are assessed by experimental results. Keywords: ASON, GMPLS, LMP, protection. [ABSTRACT FROM AUTHOR]

We study the data from a passive TCP/IP traffic measurement from a Finnish operator's GPRS/UMTS network. Of specific interest is the variability of Round Trip Times (RTTs) of TCP flows. The RTTs are analysed at micro- and macroscopic level. The microscopic level involves detailed analysis of the RTTs of individual flows, and we are able to detect, e.g., periodic behavior (via Lomb periodogram) and rate changes in the radio channel. At the macroscopic level we focus on the impact of so called self-congestion caused by bandwidth sharing at the mobile device itself, and it is shown how this seriously affects the RTTs observed by a given flow, both in GPRS and in UMTS. Keywords: traffic measurements, RTT variability, GPRS, UMTS. [ABSTRACT FROM AUTHOR]

In this paper, we present a mixed-integer linear program (MILP) designed to optimize max-min path lifetime for multicasts in directional antenna equipped networks in the presence of interference. We then employ the MILP to perform a head-to-head comparison between directional transmission and directional reception. We also propose and analyze a new directional reception heuristic. Our results indicate that directional reception can match directional transmission when extending path lifetime, with lower complexity and employing routes that use much less cumulative power. Keywords: directional antennas, optimization, maximum-lifetime, multicast. [ABSTRACT FROM AUTHOR]

OVPN (Optical Virtual Private Network) over IP (Internet Protocol)/GMPLS (Generalized Multi-Protocol Label Switching) over DWDM (Dense Wavelength Division Multiplexing) technology with QoS assurances is considered as a promising approach for the next generation OVPN. In this paper, we suggest a multicast OLSP (Optical Label Switched Path) establishment mechanism for supporting high bandwidth multicast services. For the establishment of the multicast OLSP, we propose a new multicast tree generation algorithm VS-MIMR (Virtual Source-based Minimum Interference Multicast Routing) that finds the minimum interference path between virtual source nodes. We also suggest an entire OVPN control mechanism to adapt the operation of the routing and signaling protocols of GMPLS. [ABSTRACT FROM AUTHOR]

We present a multi-gigabit rate multiple pattern-matching algorithm with TCAM that enables protecting against malicious attacks in a high-speed network. The proposed algorithm significantly reduces the number of TCAM lookups per payload with m-byte jumping window scheme. Due to the reduced number of TCAM lookups, we can easily achieve multi-gigabit rate for scanning the packet payload in order to inspect the content. Furthermore, multi-packet inspection is achieved easily by the extended state transition diagram with the shifting distance. With experimental results, we have clearly justified the proposed algorithm works well for a multi-gigabit network intrusion detection system. [ABSTRACT FROM AUTHOR]

In this paper, we propose an approach to saving power by more aggressively using sleep mode. The sleep duration is estimated by measuring the on-line traffic information, i.e. slot utilization. A considerable amount of power can be saved by using the approach. Our approach does not use any additional signaling channel, nor does it need any overhead in the involved protocol. The algorithm is readily implementable, requiring minimum processing and memory resources. Keywords: Wireless networks, 802.11, power saving, sleep mode, performance evaluation, distributed coordination function (DCF). [ABSTRACT FROM AUTHOR]

The evolution of wireless access technologies and the capabilities of today's mobile devices lead to an increasing demand of communication bandwidth. More and more packet-switched wireless access networks like Wireless Local Area Networks (WLANs) and networks based on Worldwide Interoperability for Microwave Access (WiMAX) are publicly available and operated by different providers. In order to achieve a high network coverage isolated access network providers are supposed to co-operate and to support handovers for users from access networks belonging to the same core network. Efficient authentication mechanisms are required that on the one hand exclude unauthorized users from the network and on the other hand support seamless handovers across access network boundaries. We propose a ticket-based fast re-authentication scheme that is independent from the actual authentication method and that only slightly modifies well-established standards like the Extensible Authentication Protocol (EAP) and the Remote Authentication Dial In User Service (RADIUS). As it is network technology independent, it in principle also allows fast handovers across different access network technologies. Keywords: Wireless Networks, Authentication, Handover. [ABSTRACT FROM AUTHOR]

This paper proposes a multihoming-based seamless handover scheme using a mobile router with dual egress interfaces for wireless train networks. The proposed scheme deploys dual antennas which are individually located at each end of the train for space diversity and connected to each egress interface of a mobile router. Since one of the two egress interfaces of the mobile router can continuously receive packets through its antenna while the other is undergoing a handover, the proposed scheme can support a seamless handover providing no service disruption or packet loss. [ABSTRACT FROM AUTHOR]

In this paper, the performance of four cooperative relaying schemes, which are classified by requiring a quantity of feedback information, is evaluated in the high SNR region and is compared with that of MIMO relaying schemes with two antennas. For amplify-and-forward (AF) relay, all schemes except the second hop selection scheme provide the second order diversity gain in high SNR region. For decode-and-forward (DF) relay, despite using more channel information, the coherent BF scheme does not offer the second order diversity. A system level simulation is evaluated to analyze the effects of user distribution in terms of the average capacity. For AF relay, the capacity of the cooperative relaying model is higher than that of the MIMO relaying model as about 0.2 bps/Hz. For DF relay, the MIMO relaying model provides capacity gain about larger than 0.3 bps/Hz for the coherent beamforming and the Alamouti-based scheme since the effect of array gain at relay for these schemes is more dominant factor to increase the capacity compared with the effect of reducing path loss. [ABSTRACT FROM AUTHOR]

Wireless sensor networks are characterized by the widely distributed sensor nodes which transmit sensed data to the base station cooperatively. However, due to the spatial correlation between sensor observations, it is not necessary for every node to transmit its data. There are already some papers on how to do clustering and data aggregation in-network, however, no one considers about the data distribution with respect to the environment. In this paper a context adaptive clustering mechanism is proposed, which tries to form clusters of sensors with similar output data within the bound of a given tolerance parameter. With similar data inside a cluster, it is possible for the cluster header to use a simple technique for data aggregation without introducing large errors, thus can reduce energy consumption and prolong the sensor lifetime. The algorithm proposed is very simple, transparent, localized and does not need any central authority to monitor or supervise it. [ABSTRACT FROM AUTHOR]

One of the major challenges faced by the IPv6 community in recent years has been to define the scenarios in which transitioning mechanisms should be used and which ones should be selected given a specific scenario. This paper aims to supplement this by presenting the results of a comparative evaluation carried out on three major IPv6 interoperation mechanisms; NAT-PT, TRT and DSTM. This work attempts not only to determine the outright performance of each mechanism against the other but also against a theoretical evaluation of the specification. Our results show that while DSTM performs well both NAT-PT and TRT place significant overheads on the network. Keywords: IPv6, Transitioning Mechanisms, NAT-PT, TRT, DSTM. [ABSTRACT FROM AUTHOR]

Core network micro-mobility solutions resolve L3 handovers and may be based on the Internet Protocol (IP) or on Multi-Protocol Label Switching (MPLS). When a micro-mobility solution triggers the L3 handover before the L2 handover, it is called predictive, otherwise reactive. The outage period due to the handover is smaller for predictive solutions. However, in order to be predictive, a L3 mobility solution needs support from the underlying link-layer. This support may be provided with the help of IEEE 802.21 that is exploited for intra-technology handovers in WLANs in this paper. [ABSTRACT FROM AUTHOR]

Since web prefetching techniques were proposed in the second half of the 90s as mechanisms to reduce final users' perceived latency, few attempts to evaluate their performance have been done in the research literature. Even more, to the knowledge of the authors this is the first study that evaluates different proposals from the user's point of view, i.e., considering the latency perceived by the user as the key metric. This gap between the proposals and their correct performance comparison is due to the difficulty to use a homogeneous framework and workload. This paper is aimed at reducing this gap by proposing a cost-benefit analysis methodology to fairly compare prefetching algorithms from the user's point of view. The proposed methodology has been used to compare three of the most used algorithms in the bibliography, considering current workloads. [ABSTRACT FROM AUTHOR]

In this paper, the performance of IEEE802.16e random access protocol with handover procedure is examined in terms of access throughput and mean access delay, by using equilibrium point analysis(EPA). In the analysis, retransmission probability, which is a typical input parameter in the literature so far, is iteratively obtained from equilibrium number of backlogs in the system in conjunction with a binary exponential backoff algorithm. In numerical examples, the effects of SSs' mobility on access throughput and mean access delay are examined. [ABSTRACT FROM AUTHOR]

A cross-layer optimization problem to maximize utilization for a distributed real-time medium access control (MAC) protocol supporting variable bit rate (VBR) multiclass services is formulated. A complete sharing (CS) scheme is used as the admission control policy at the connection level to relate the maximum number of devices that can be admitted in the wireless personal area network (WPAN) to the grade of service (GoS) of blocking probability at the connection level, the quality of service (QoS) of packet loss probability at the packet level and the effective data transmission slots efficiency at the MAC layer. With this cross-layer analytical framework, the maximum number of devices that can be admitted into the system to achieve maximum utilization while maintaining prescribed GoS/QoS requirements under different total device mean connection arrival rate can be determined. Numerical results are presented to demonstrate the effectiveness of the proposed cross-layer coupling strategy. [ABSTRACT FROM AUTHOR]

There is significant interest in the network management community about the need to improve existing techniques for clustering multi-variate network traffic flow records so that we can quickly infer underlying traffic patterns. In this paper we investigate the use of clustering techniques to identify interesting traffic patterns in an efficient manner. We develop a framework to deal with mixed type attributes including numerical, categorical and hierarchical attributes for a one-pass hierarchical clustering algorithm. We demonstrate the improved accuracy and efficiency of our approach in comparison to previous work on clustering network traffic. [ABSTRACT FROM AUTHOR]

In this paper, a multicast scheme for UMTS which only requires insignificant modifications in the current UMTS network infrastructure is analyzed. We analytically present the multicast routing mechanism behind our scheme as well as the multicast group management functionality of it. Furthermore, we present an evaluation of our scheme in terms of its performance. The critical parameters for the evaluation of the scheme are the number of multicast users within the multicast group, the amount of data sent to the multicast users, the density of the multicast users within the cells and the type of transport channel used for the transmission of the multicast data over the air. [ABSTRACT FROM AUTHOR]

This paper first introduces bandwidth utilization metric and then analyzes sorted-priority schedulers in the terms of the metric. The results show that the utilization is directly proportional to both the number of delay bound classes and the dependency of delay bound on rate but inversely proportional to packet size. [ABSTRACT FROM AUTHOR]

Currently, the contention resolution is one of research focuses for optical burst switching (OBS). The paper presents a new contention resolution scheme, named as adaptive parameter-based deflection routing, which can control the deflection according to the time-varying traffic load and the QoS requirements. Compared with other schemes, the simulation results show that it can improve the overall BLP and the individualBLP of each class burst, and alleviate the offset-time deficit on QoS guarantee. Keywords:Contention, Deflection Routing, Optical Burst Switching, QoS. [ABSTRACT FROM AUTHOR]

The Optical Burst Switching (OBS) technology itself is still in the early stage of development and various studies are often performed independently, resulting in difficult comparison between individual data sets (including such controversial studies as burst/packet loss evaluation). To facilitate the future research and evaluation of OBS networks, in this paper we examine relations between standard network parameters and the resulting network offered load, creating a common ground for comparing various simulation results. Means of estimating the resulting network offered load based on parameters describing the network topology and type of traffic are developed and examined for various simulation scenarios (topologies, loads, etc.). It is argued that, given the target offered load value for a given topology, it is always possible to estimate the required idle time which had to be applied in the network nodes, in order to keep the offered network load at the pre-defined level. Keywords: Optical Burst Switching Networks, Network Simulation, Network Offered Load, Network Load Estimation. [ABSTRACT FROM AUTHOR]

In this paper, we study the following problem. Given the network topology and traffic demand, determine how a minimum set of wavelength converters should be placed to ensure that the number of wavelengths needed will not exceed a given bound L+u, where L is the maximum link load in the network and u is a parameter defined by the network designer to reflect the overall availability of wavelength resources. This problem, however, is proved to be NP-hard. Hence we develop an efficient heuristic algorithm and extensive theoretical and experimental studies are carried out to verify the effectiveness and performance of the algorithm. [ABSTRACT FROM AUTHOR]

Ethernet-over-SONET/SDH (EoS) with virtual concatenation is a popular approach for interconnecting geographically distant Ethernet segments using the SDH transport infrastructure. In this paper, we introduce a new concatenation technique, referred to as cross-virtual concatenation (CVC), which involves the concatenation of virtual channels (VCs) of hetrogenous capacities and can be implemented by a simple upgrade at SDH end nodes, thus utilizing the existing legacy SDH infrastructure. By employing CVC for EoS systems, we show that the SDH bandwidth can be harvested more efficiently than in conventional virtual concatenation. We later consider the routing problems associated with CVC connections, namely the connection establishment problem and the connection upgrade problem. We propose ILP and heuristic solutions to solve such problems. Simulations are conducted to evaluate the performance of the proposed heuristic and to demonstrate the advantages of employing CVC. [ABSTRACT FROM AUTHOR]

Disjoint multipath routing (DMPR) is an effective strategy to achieve robustness in networks, where data is forwarded along multiple link- or node-disjoint paths. DMPR poses significant challenges in terms of obtaining loop-free multiple (disjoint) paths and effectively forwarding the data over the multiple paths, the latter being particularly significant in datagram networks. One approach to reduce the number of routing table entries for multipath forwarding is to construct two trees, namely red and blue, rooted at a destination node such that the paths from a source to the destination on the two trees are link/node-disjoint. This paper develops the first distributed algorithm for constructing the colored trees whose running time is linear in the number of links in the network. The paper also demonstrates the effectiveness of employing generalized low-point concept rather than traditional low-point concept in the DFS-tree to reduce the average path lengths on the colored trees. [ABSTRACT FROM AUTHOR]

In recent years, overlay networks have emerged as an attractive alternative for supporting value-added services. Due to the difficulty of supporting end-to-end QoS purely in end-user overlays, backbone overlays for QoS support have been proposed. In this paper, we describe a backbone QoS overlay network architecture for scalable, efficient and practical QoS support. In this architecture, we advocate the notion of QoS overlay network (referred to as QSON) as the backbone service domain. The design of QSON relies on well-defined business relationships between the QSON provider, network service providers and end users. A key challenge in making QSON a reality consists of efficiently determining routes for end user QoS flows based on the service level agreements between the QSON provider and network service providers. In this paper, we propose and present a scalable and distributed QoS routing scheme that can be used to efficiently route end user QoS flows through QSON. We demonstrate the effectiveness of our solution through simulations. [ABSTRACT FROM AUTHOR]

Many large ISP networks today rely on route-reflection [1] to allow their iBGP to scale. Route-reflection was officially introduced to limit the number of iBGP sessions, compared to the sessions required by an iBGP full-mesh. Besides its impact on the number of iBGP sessions, route-reflection has consequences on the diversity of the routes known to the routers inside an AS. In this paper, we quantify the diversity of the BGP routes inside a tier-1 network. Our analysis shows that the use of route-reflection leads to a very poor route diversity compared to an iBGP full-mesh. Most routers inside a tier-1 network know only a single external route in eBGP origin. We identify two causes for this lack of diversity. First, some routes are never selected as best by any router inside the network, but are known only to some border routers. Second, among the routes that are selected as best by at least one other router, a few are selected as best by a majority of the routers, preventing the propagation of many routes inside the AS. We show that the main reason for this diversity loss is how BGP chooses the best routes among those available inside the AS. Keywords: BGP, iBGP, route-reflection, route diversity. [ABSTRACT FROM AUTHOR]

Quality of Service support plays a major role in the Next Generation Internet. QoS routing protocols must cope with service differentiation to enhance this support. This paper proposes a service aware QoS routing protocol, the Multi-Service routing, which is an extension to traditional intra-domain routing protocols. It proposes a new path selection policy that guides higher priority traffic through the shortest path and diverts lower priority traffic through longer paths when service performance degradation is foreseen. Simulations results shows that the proposed routing performs better than existing QoS routing and link-state protocols. [ABSTRACT FROM AUTHOR]

Frequency-hopping (FH) methods in the Orthogonal frequency division multiplexing access(OFDMA) system,which are to assign user-specific subcarrier to the active users, have been paid much attention to in the broadband wireless communication system. In this paper, we present a novel multiple access scheme, referred to as CDM-FH-OFDMA, which is the extension of FH-OFDMA with code division multiplexing (CDM). This scheme can exploit the frequency diversity gain without the aid of channel coding. And it also can be employed in the multi-cell environment with one frequency reuse factor. Computer simulation demonstrates effectiveness of CDM-FH-OFDMA and the conclusion is followed. Keywords: OFDM, FH, CDM. [ABSTRACT FROM AUTHOR]

The wireless cellular networks have evolved from IS-95A/B to cdma2000 1X, EV-DO, and WCDMA to improve data service quality. A carries also preserve in their efforts to rev up wireless data service. Despite this efforts, call setup latency has occurred on cdma2000 1X and EV-DO systems. It is an impediment to data service activation. In measuring the real delay time during call establishment from MS to BSC, PCF and PDSN, it is found out that point-to-point protocol between MS and PDSN is major source of delay. Therefore, a simplified PPP is proposed, considering the difference in transmission speed of links among nodes. Then the inter-working scenarios between MS and PDSN is presented with simplified PPP and/or legacy PPP, and the proposed scheme is verified with superior performance over legacy PPP, through comparing the number of packets required for data call setup. Keywords: Simplified PPP, Call setup latency, Cdma2000 system, Wireless packet data service. [ABSTRACT FROM AUTHOR]

This paper is a sequel of previous work, in which we proposed a model and computational technique to calculate the Erlang capacity of a single CDMA cell that supports elastic services. The present paper extends that base model by taking into account two important features of CDMA. First, we capture the impact of soft blocking by modeling the neighbor cell interference as a lognormally distributed random variable. Secondly, we model the impact of the outage by taking into account that in-progress sessions can be dropped with a probability that depends on the current load in the system. We then consider a system with elastic and rigid service classes and analyze the trade-off between the total (soft and hard) blocking probabilities on the one hand and the throughput and the session drop probabilities on the other. [ABSTRACT FROM AUTHOR]

In this paperThis work is supported by a grant from Samsung Advanced Institute of Technology. , we propose a fast handoff method for seamless multimedia service in IEEE 802.11 WLAN. The proposed method uses an improved access point (AP) with additional radio frequency (RF) module, SNIFFER, monitoring the movement of the station (STA). By using the SNIFFER, the proposed method can completely remove the probe delay. Furthermore, we also propose an effective handoff decision method taking into account the quality of service (QoS) in the application layer. The proposed method uses packet loss information and the received signal strength indication (RSSI) for the handoff decision. Experimental results show that the proposed method can improve the performance of the seamless multimedia service by drastically reducing the handoff delay and packet loss. [ABSTRACT FROM AUTHOR]

Packet filters have traditionally been used to shield IP networks from known attack flows, ususally within firewall systems connecting trusted and non-trusted network segments. As IP networks grow and tend to connect to more and more neighbor networks with unknown trust status, carrier-grade operators in particular are beginning to experience raising costs due to increasingly complex filter configurations that have to be applied to their networks, in order to maintain a desired security level. In this paper, we present a discussion on the general properties of distributed packet filter configurations and an algorithm for a simplified compilation of anticipatory static packet filter configurations in heterogenous IP networks. Keywords: Network Security, IP Spoofing, Packet Filters, Critical Infrastructure Protection. [ABSTRACT FROM AUTHOR]

In this paper a new aspect of the classical max-min fairness fixed-path problem is investigated. The considered (multi-criteria) optimization problem is almost identical to the continuous-flow problem, with the additional complicating assumption that flows must be integral. We show that such an extension makes the problem substantially more difficult (in fact -hard). Through comparison with the closely related continuous-flow problem, a number of properties for the solution of the extended problem are derived. An algorithm, based on sequential resolution of linear programs, that shows to be useful (produce optimal solutions) for many instances of the considered problem, is given. It follows that this algorithm can be made exact, through substituting the involved linear programs by mixed-integer programs. Keywords: Max-min fairness, Network optimization, Modular flows. [ABSTRACT FROM AUTHOR]

Many users require IP networks with the capacity to guarantee a minimum throughput even during periods of congestion. Furthermore, it is also desirable to share the excess unsubscribed bandwidth among active users if aggregate demand does not exceed network capacity. This kind of service, named assured service, can be provided through the Assured Forwarding (AF) Per Hop Behavior (PHB) defined in the DiffServ architecture. DiffServ mechanisms require special networking support at both the edge and the core nodes to guarantee the differentiated service. In this paper we propose the Ping Trunking scheme as a suitable mechanism to provide assured services to network users without the need for modifying core nodes. Ping Trunking is an edge-to-edge management technique that completely addresses the regulation of aggregate traffic streams at the edge of the network. In addition, it also overcomes some unfairness issues found in AF when sharing the available bandwidth among heterogeneous aggregates. Simulation results have validated the effectiveness of our proposal. Keywords: DiffServ, assured services, aggregated traffic, congestion control. [ABSTRACT FROM AUTHOR]

Efficient dynamic resource provisioning algorithms are necessary to the development and automation of Quality of Service (QoS) networks. The main goal of these algorithms is to offer services that satisfy the QoS requirements of individual users while guaranteeing at the same time an efficient utilization of network resources. In this paper we introduce a new service model that provides quantitative per-flow bandwidth guarantees, where users subscribe for a guaranteed rate; moreover, the network periodically individuates unused bandwidth and proposes short-term contracts where extra-bandwidth is allocated and guaranteed exclusively to users who can exploit it to transmit at a rate higher than their subscribed rate. To implement this service model we propose a dynamic provisioning architecture for intra-domain Quality of Service networks. We develop an efficient bandwidth allocation algorithm that takes explicitly into account traffic statistics to increase the users' benefit and the network revenue simultaneously. We demonstrate through simulation in realistic network scenarios that the proposed dynamic provisioning model is superior to static provisioning in providing resource allocation both in terms of total accepted load and network revenue. Keywords: Dynamic Bandwidth Allocation, Autonomic Networks, Service Model. [ABSTRACT FROM AUTHOR]

We present a novel idea for energy saving by avoiding the reception of redundant broadcast frames. It is based on sending an abstract frame just before a data frame: the former contains a digest of the latter. We evaluate the energy savings of this scheme analytically and by means of simulation in ns-2. Although we have applied our approach to SMAC, the key idea is generic and can be used to reduce energy consumed by broadcast frames in a large variety of MAC protocols. [ABSTRACT FROM AUTHOR]