An architecture for residential Internet telephony service

A new architecture that can be used for offering an Internet telephony service to residential customers is introduced. The architecture addresses scalability and availability requirements of mass-market deployment of carrier-grade services and supports interconnection with SS7 for Internet telephony calls to the public switched telephone network. The architecture is based on the concept of a gateway decomposition that separates the media transformation function of today's H.323 gateways from the gateway control function of the gateways and centralizes the intelligence in a call agent. The media gateway control protocol is introduced as the protocol between the call agent that assumes the gateway control function and the gateway that provides just the media transformation function. Interworking between the architecture and the public switched telephone network, the session initiation protocol, and H.323 are also discussed     

家庭网关

文章介绍了家庭网关作为家庭智能化设备互联并获得In-ternet服务的桥梁,具有良好的发展前景.通过家庭网关的软硬件结构分析和不同实现形式的介绍,阐述了家庭网关实现的关键技术与标准.要构建一个低成本、高质量的普及型家庭网关,网关设备必须具备协议一致、升级方便、操作简便、高稳定性等特点.     

Context‐aware hybrid satellite‐terrestrial broadband access

One of the key performance targets on the European Commission's Digital Agenda is to provide at least 30‐Mbit/s broadband coverage to all European households by 2020. The deployment of existing terrestrial technologies will not be able to satisfy the requirements in the most difficult‐to‐serve locations, either due to a lack of coverage in areas where the revenue potential for terrestrial service providers is too low or due to technological limitations that diminish the available throughput in rural environments. In this paper, we investigate a hybrid broadband system combining satellite and terrestrial access networks. The system design and the key building blocks of the intelligent routing entities (referred to as intelligent gateways) are presented. To justify the hybrid broadband system's performance subjectively, lab trials have been performed with an integrated multiple access network emulator and a variety of typical multimedia applications that have varying requirements. The results of the lab trials suggest that the quality of experience is consistently improved thanks to the utilisation of intelligent gateway devices, when compared with using a single access network at a time.     

基于多核的安全网关设计与实现

传统的安全网关大多基于单核系统开发,受限于硬件发展的瓶颈,单核难以满足日益增长的网络性能要求。该文提出了一种基于多核的安全网关的设计模型,并根据此模型实现了一款安全网关,经过测试表明,此款安全网关的实现与通用安全网关相比性能优异,满足高性能网络安全的需要。     

A comparison of competing broadband in-home technologies

Connecting each house to a broadband access network represents an unprecedented opportunity to offer added-value services and broadband Internet access to residential users and expand the customer base beyond the corporate environment. Home networks, however, may be the last barrier to end-to-end multimedia service provisioning. Although a large number of houses have PCs, modems or multimedia network-enabled appliances, the majority are not equipped to support their interconnection, and most consumers are unwilling or cannot afford large-scale home rewiring. This paper reviews the available home-networking technologies and provides a comparison of the competing broadband in-home technologies. The focus is on technologies that do not require rewiring the home, either reusing the existing wiring or using wireless technology. The paper also discusses the residential gateway (RG) initiative, which provides a single point of convergence between the in-home and the access networks     

Do we need quality of service in the customer environment?

The paper introduces the concept of quality of service (QoS) in the customer environment, as related to broadband customer premises equipment. The paper describes the BT vision for the customer environment, with a QoS-enabled ‘customer gateway’ and ‘home networks’ delivering a range of broadband services to the end user. The reasons behind the need for QoS are discussed and the differing requirements of the downstream (network to end user) as distinct from the upstream (end user to network) data paths are described.Incorporating downstream QoS protocols in the customer gateway is less likely to give an effective perceived performance benefit due to the simple fact that the traffic priority is essentially predetermined by the network/service provider and only marginal benefits can be seen by its application. Extending downstream QoS across the home network will be essential to provide an effective customer experience. The paper looks at the future strategy for implementing QoS, not just within the customer gateway, but also up to the end terminal, as it should be remembered that all elements of the service such as end user appliances, home networks, customer gateways, the network provider and service provider all have their own distinct parts to play to guarantee the best quality of service and customer experience.The paper concludes that the predominant area for QoS implementation in the customer environment, is in the upstream direction where even a basic QoS implementation such as simple queuing is likely to give noticeable improvements in the customer experience. New real-time services such as voice over IP (VoIP) will require upstream QoS.Thus it should be possible to specify QoS enhancements that are straightforward and likely to be simple (and therefore cost effective) to implement, in low-cost CPE. The paper concludes that it is essential that the next generation of customer gateways and home networks, support appropriate QoS functionality to support new services delivered over BT’s network.     

电信运营商网关局建设的新模式

本文通过江西联通本地网两网网关局路由组织优化,以互为备份,提出了中国联通与中国电信C网网间新建本地互联互通关口局建设的新模式,供借鉴。     

A vision for residential broadband services: ATM-to-the-home

The arrival of asynchronous transfer mode (ATM) networks has enabled a wide range of new interactive multimedia applications for the residential market. The article presents a vision for supporting universal residential broadband services based on an ATM-to-the-home (ATTH) network architecture. This network architecture applies to the various residential access network (RAN) architectures being deployed today, such as hybrid fiber/coax (HFC), fiber-to-the-curb (FTTC), fiber-to-the-home (FTTH), and asymmetric digital subscriber loop (ADSL) technologies. The article addresses today's residential networks and applications, to understand why a switched broadband residential network is required to support residential broadband services. After exploring residential broadband application requirements, a new class of service is proposed to support a very important class of residential broadband applications that has been not addressed. Then, the technical and strategic motivations for using the ATTH architecture are discussed in detail. A universal model for residential broadband network architecture based on ATTH is described, which is shown to apply to various RAN architectures. Finally, it discusses the signaling requirements of residential broadband services and explain why the ATM multiconnection per-call model is much more efficient than the digital stored media command and control (DSM-CC) session control protocol approach for the ATTH architecture     

A Traffic Engineering Approach for Placement and Selection of Network Services

Network services are provided by means of dedicated service gateways, through which traffic flows are directed. Existing work on service gateway placement has been primarily focused on minimizing the length of the routes through these gateways. Only limited attention has been paid to the effect these routes have on overall network performance. We propose a novel approach for the service placement problem, which takes into account traffic engineering considerations. Rather than trying to minimize the length of the traffic flow routes, we take advantage of these routes in order to enhance the overall network performance. We divide the problem into two subproblems: finding the best location for each service gateway, and selecting the best service gateway for each flow. We propose efficient algorithms for both problems and study their performance. Our main contribution is showing that placement and selection of network services can be used as effective tools for traffic engineering.     

Random early detection gateways for congestion avoidance

The authors present random early detection (RED) gateways for congestion avoidance in packet-switched networks. The gateway detects incipient congestion by computing the average queue size. The gateway could notify connections of congestion either by dropping packets arriving at the gateway or by setting a bit in packet headers. When the average queue size exceeds a present threshold, the gateway drops or marks each arriving packet with a certain probability, where the exact probability is a function of the average queue size. RED gateways keep the average queue size low while allowing occasional bursts of packets in the queue. During congestion, the probability that the gateway notifies a particular connection to reduce its window is roughly proportional to that connection's share of the bandwidth through the gateway. RED gateways are designed to accompany a transport-layer congestion control protocol such as TCP. The RED gateway has no bias against bursty traffic and avoids the global synchronization of many connections decreasing their window at the same time. Simulations of a TCP/IP network are used to illustrate the performance of RED gateways     

基于MANET接入Internet的动态 网关布局与选取规划模型

 本文以实现MANET接入Internet为应用背景,考虑到动态网关在整个网络接入过程中的重要作用,提出了一种新的适用于MANET接入Internet的动态网关的布局与选取的三层规划模型.该模型通过引入具有协调控制功能的节点(即决策节点)来对接入网络中的网关和路径的使用情况进行调控,通过上下层的交互决策协调网络整体利益和节点局部利益之间的关系,并以此作为配置网关的依据,从而优化网关布局.仿真结果表明,引入该模型后网络的延迟、开销以及吞吐率等性能指标得到了改善,验证了该模型的有效性.     

Design of scalable and efficient multi-radio wireless networks

A proper design of Wireless Mesh Networks (WMNs) is a fundamental task that should be addressed carefully to allow the deployment of scalable and efficient networks. Specifically, choosing strategic locations to optimally place gateways prior to network deployment can alleviate a number of performance/scalability related problems. In this paper, we first, propose a novel clustering based gateway placement algorithm (CBGPA) to effectively select the locations of gateways. Existing solutions for optimal gateway placement using clustering approaches are tree-based and therefore are inherently less reliable since a tree topology uses a smaller number of links. Independently from the tree structure, CBGPA strategically places the gateways to serve as many routers as possible that are within a bounded number of hops. Next, we devise a new multi-objective optimization approach that models WMN topologies from scratch. The three objectives of deployment cost, network throughput and average congestion of gateways are simultaneously optimized using a nature inspired meta-heuristic algorithm coupled with CBGPA. This provides the network operator with a set of bounded-delay trade-off solutions. Comparative simulation studies with different key parameter settings are conducted to show the effectiveness of CBGPA and to evaluate the performance of the proposed model.     

移动自组网与Internet互连的动态网关策略

移动自组网(MANET)是自治的无基础设施的网络,它通过IP路由支持多跳无线通信。它与Internet 相比存在着许多差异,不仅有网络拓扑结构的不同,还存在通信方式的不同。因此,MANET与Internet组合成混杂网络(hybrid network)是一个具有挑战性的课题。移动自组网(MANET)的结点要进行Internet连接,就必须寻找Internet网关。如何寻找和维持与Internet网关的连接是这个问题的关键,再者,就是如何切换到一个更合适的相邻网关。在这篇文章中,首次提出动态网关的概念,动态网关作为MANET和Internet之间的接口起桥梁作用。通过模型分析,证明动态网关体系结构适合于自组网与Internet互联。仿真结果显示,利用动态网关的网络性能优于单一固定网关的体系结构的网络性能。     

Dense cluster gateway based routing protocol for multi-hop mobile ad hoc networks

In a multi-hop mobile ad hoc network dynamic clusterization of nodes can be quite effective for better management of routing problems. In a cluster based protocol inter cluster data transfer takes place through the cluster gateways. Therefore, it is important to maintain information about the gateways as a part of the routing tables in order that the inter cluster routing proceeds smoothly even as the nodes move about. In this paper we propose a randomized approach for inter cluster routing over dense cluster gateways (DCG). A group of large number of gateway edges between two adjacent clusters offering inter cluster connectivity between the two is referred to as a DCG. The minimum number of gateway edges that define a DCG is dependent on the characteristics of particular ad hoc network. A DCG is expected to offer robust inter cluster connectivity as it typically has a large number of gateway edges. Our protocol is an improvement over the cluster based routing using k-tree core backbone proposed in [Information Processing Letters 88 (2003) 187–194]. It distributes the routing load on the cluster gateways without adding the extra overhead of maintaining information about dense cluster gateways. We also propose a heuristic which reduces the load on the cluster-heads. The heuristic elects some nodes to act as sub-cluster-heads which share a part of the workload of the respective cluster-heads. The protocol has been implemented on ns-2 simulator. An analysis of the result of the experiments has been presented.     

Gateway Placement for Throughput Optimization in Wireless Mesh Networks

In this paper, we address the problem of gateway placement for throughput optimization in multi-hop wireless mesh networks. Assume that each mesh node in the mesh network has a traffic demand. Given the number of gateways to be deployed (denoted by k) and the interference model in the network, we study where to place exactly k gateways in the mesh network such that the total throughput is maximized while it also ensures a certain fairness among all mesh nodes. We propose a novel grid-based gateway deployment method using a cross-layer throughput optimization, and prove that the achieved throughput by our method is a constant times of the optimal. Simulation results demonstrate that our method can effectively exploit the available resources and perform much better than random and fixed deployment methods. In addition, the proposed method can also be extended to work with multi-channel and multi-radio mesh networks under different interference models.     

Multimedia streaming in Multi-Homed Hybrid Ad Hoc Networks: A model of network connectivity

In this paper we consider the scenario of a Multi-Homed Hybrid Ad Hoc Network, which consists of self-organized and self-configured mobile nodes that make use of two or more fixed gateways to connect to the Internet. Accordingly, different network segments are formed, each one associated with a different gateway. A node can maintain its connectivity to the Internet when moving from a network to another by performing handover procedures and changing its gateway to the Internet. This scenario is quite interesting for its capacity of increasing the geographical extension of a single mobile network. Within this scenario we focus on the modelling of the node connectivity, which is of practical interest for the design of rate control algorithms for multimedia streaming systems. We consider a network structure with gateways placed in a honey cell structure, where nodes move according to the RDMM (Random Direction Mobility Model). We then derive the probabilities for a node to change the route to connect to the Internet and to handover from a network to another, which both cause service interruptions that heavily affect the quality in multimedia streaming services. Numerical results show the accuracy of the proposed theoretical model with respect to simulated data and reveal the benefits of the model in controlling playback buffer starvation occurrences during video streaming.     

QoS-enabled residential gateway architecture

As networking technologies penetrate wide varieties of devices for daily usage, home networks are becoming a reality. The bandwidth and always-on connectivity provided by the rapidly growing broadband technologies, such as cable and digital subscriber line (DSL), render home networking even more attractive. A residential gateway is a device that interconnects various home devices to one another as well as to the Internet. The home networks being deployed today are simple and inexpensive with the residential gateway providing only connectivity. As home networks evolve and become more widespread, emerging applications on home networks will demand additional features that require quality of service. We present an architecture of a next-generation QoS-enabled residential gateway. Such a residential gateway, in conjunction with the developments in QoS-enabled wireless LAN technologies, will usher in a new generation of home networks that are capable of supporting a wide range of applications.     

GI/Geom/1 queue based on communication model for mesh networks

In mesh networks architecture, it should be permitted to visit the mobile client points. Whereas in mesh networks environment, the main throughput flows usually communicate with the conventional wired network. The so‐called gateway nodes can link directly to traditional Ethernet, depending on these mesh nodes, and can obtain access to data sources that are related to the Ethernet. In wireless mesh networks (WMNs), the quantities of gateways are limited. The packet‐processing ability of settled wireless nodes is limited. Consequently, throughput loads of mesh nodes highly affect the network performance. In this paper, we propose a queuing system that relied on traffic model for WMNs. On the basis of the intelligent adaptivenes, the model considers the influences of interference. Using this intelligent model, service stations with boundless capacity are defined as between gateway and common nodes based on the largest hop count from the gateways, whereas the other nodes are modeled as service stations with certain capacity. Afterwards, we analyze the network throughput, mean packet loss ratio, and packet delay on each hop node with the adaptive model proposed. Simulations show that the intelligent and adaptive model presented is precise in modeling the features of traffic loads in WMNs. Copyright © 2013 John Wiley & Sons, Ltd.     

Multiple gateway placement in large‐scale constellation networks with inter‐satellite links

Multiple gateways are required in large satellite constellation networks (LSCNs) with inter‐satellite links (ISLs), and their placement may greatly affect the system performance. Gateway placement can be optimized to achieve better network performance under the non‐uniform ground demand distribution. This paper formulates a gateway placement optimization model for LSCN with ISLs, aiming at achieving an optimal overall performance including delay, traffic peak, and load balance. The constraints of potential gateway location, gateway‐satellite connectivity, and max hop‐count are considered. A genetic algorithm (GA)‐based method is proposed to solve the integer optimization problem with the help of quasi‐evenly distributed reference layout. A Starlink‐like constellation with ISLs is adopted in the simulation. The simulation results show that the optimized layout has better performance than the reference layout. Additionally, the locations with high user demand or at the middle of ocean are preferred by gateways. The network performance is jointly influenced by gateway placement, demand distribution, constellation configuration, node, and link capacities. The abnormally high ISL hop‐count is found in the south Indian Ocean, which is caused by constellation and ISL configuration.     

An efficient traffic control system using dynamic thresholding techniques in wireless mesh networks

Wireless mesh networks (WMNs) depend on a resilient and high‐performance infrastructure to provide users pervasive Internet access. In WMNs, all Internet traffic will be forwarded to the Internet gateways. Hence, these gateways are generally bottleneck nodes. This work proposes a traffic control technique to reduce the bottleneck problem and increase the utilization of network resources. Our approach provides a traffic control strategy that exploits dynamic techniques to adjust the threshold according to the traffic load of each gateway. The base threshold is defined in order to effectively control the traffic. When the current load exceeds the threshold of a gateway, the traffic redirection strategy is implemented by switching border nodes. The service regions can be adjusted for each gateway based on the traffic load. Furthermore, the proposed dynamic thresholding approaches can distribute the workloads of gateways and maintain the thresholds of any two gateways within a level range, making an in‐band balance of load. Thus, our proposed scheme can handle the unnecessary traffic redirection and reduce the traffic control overhead for various distributions of traffic. Experimental results demonstrate that our scheme outperforms other schemes in terms of packet delivery ratio and efficiency, especially in bursty traffic environments. Copyright © 2010 John Wiley & Sons, Ltd.