IP-over-SONET和IP-over-ATM技术比较

Ｉｎｔｅｒｎｅｔ的快速发展对广域网带宽提出了更高的要求。Ｉｎｔｅｒｎｅｔ服务供应商（ＩＳＰ）一直在寻找更快的主干路由器互连方式。最近面市的解决方案导致许多ＩＳＰ部署了多种ＩＰ－ｏｖｅｒ－ＡＴＭ技术,如局域网仿真和一般ＩＰｏｖｅｒ ＡＴＭ技术。由于运营商提供的底层设施是在广域光纤链路上部署的ＳＯＮＥＴ或ＳＤＨ,因此人们越来越多地关注在ＳＯＮＥＴ上直接运行ＩＰ,而不是通过ＡＴＭ网络,以提高带宽效率。但是在这两种备选方案中,到底哪种技术提供了最佳方案,业内一直存在着很大的争议。 ＩＰ－ｏｖｅｒ－ＡＴＭ…     

宽带数据通信网的演进

尽管ＩＰ化已成为宽带数据网络的演进方向,但电信运营商在选择融合网络解决方案时比较现实的选择是优化现有传送网基础设施,同时要兼顾公司目前或将要提供的业务。在光联网方案讨论中,文章对ＩＰ ｏｖｅｒ ＳＤＨ和ＩＰ ｏｖｅｒ ＡＴＭ进行了比较,认为集成型ＩＰｏＡ被看好。但由于ＡＴＭ的局限性,未来的联网方案将是基于ＤＷＤＭ的光互联网,而ＡＴＭ将演变为一种边缘技术,网络智能也将随之转移至网络边缘。     

建设新型电信级光互联网

要实现从叠加网络向统一的多业务网络的过渡,运营商需要新一代的边缘路由平台　　随着ＩＰ业务的增长,通信业在高容量光网络上的投资持续高速增长。在光层上叠加ＳＯＮＥＴ再叠加ＡＴＭ再叠加ＩＰ的运行方式已不再是必需的了。取而代之的是ＩＰ ｏｖｅｒＳＯＮＥＴ,或者ＩＰ ｏｖｅｒ ＤＷＤＭ,因而消除了不必要的开销。在这种新型网络中（即光互联网）,多协议标签交换（ＭＰＬＳ）传送正在成为融各层于一层的既提高性能,又简化网络结构的传送方式。 ＤＷＤＭ和光交换的广泛实施提供了巨大的带宽,为光互联网的发展创造了巨大的契机。…     

基于SDH的宽带IP网

采用ＩＰ ｏｖｅｒＳＤＨ技术的ＩＰ骨干网提供了高效、经济的高速ＩＰ业务传输。介绍了采用ＩＰ ｏｖｅｒＳＤＨ的缘由、ＩＰ ｏｖｅｒＳＤＨ协议和接口规范以及ＩＰ ｏｖｅｒＳＤＨ在实际中的应用。最后,对高速宽带ＩＰ网络的未来作了展望。     

未来光网络中的光交换路由器

一、引言 ＩＰ业务的增长产生了巨大的带宽需求,ＤＷＤＭ技术的发展可以提供超大容量的带宽资源,使以ＩＰ为基础的网络和传输网络实现最佳的综合和提高。然而,在当前的ＩＰ承载数据网络中,为了确保数据业务的有效传输和ＱｏＳ,４个功能层是必不可少的,即ＩＰ ｏｖｅｒ ＡＴＭ ｏｖｅｒ ＳＤＨ ｏｖｅｒ ＷＤＭ,ＩＰ层承载应用程序,ＡＴＭ层处理流量控制,ＳＤＨ层管传输,ＤＷＤＭ层提供大容量的带宽。这种开销巨大、功能重叠的多层协议结构所面临的典型问题就是最小公分母效应,任何一个功能层都可能限制整个网络的扩展能力。因此…     

IP-over-SONET和IP-over-ATM的技术比较

近年来,Ｉｎｔｅｒｎｅｔ的快速发展对广域网带宽提出了更高的要求。Ｉｎｔｅｒｎｅｔ服务供应商ＩＳＰ一直在寻找更快的主干路由器互连方式。最近面市的Ｉｎｔｅｒｎｅｔ解决方案,导致许多ＩＳＰ部署了多种ＩＰ－ｏｖｅｒ－ＡＴＭ技术,如局域网仿真和一般ＩＰ ｏｖｅｒ ＡＴＭ技术。由于运营商提供的底层设施是在广域光纤链路上部署的同步光网络 ＳＯＮＥＴ 或同步数字分层 ＳＤＨ,因此人们越来越多地关注在ＳＯＮＥＴ上直接运行ＩＰ,而不是采用ＡＴＭ网络,以提高带宽效率。但是在这两种备选方案中,到底哪种技术提供了最佳方案,业内一直存在着很大的争议。一、ＩＰ－ｏｖｅｒ－ＡＴＭＩｎｔｅｒｎｅｔ工程任务小组ＩＥＴＦ把ＩＰ定义为,把多个异构网络连成一个大型互连网络的公共“粘合剂”。各个网络可以采用不同的物理层、链路层和网络层技术。但是,如果ＩＰ层在各个网络层的顶部运行,那么可以把多个网络无缝地互连起来。Ｉｎｔｅｒｎｅｔ工程任务小组定义了运行ＩＰ的各种网络技术,包括广播局域网技术（如以太网）、电路交换广域网技术（如Ｘ．２５）和分组交换广域网技术（如交换式多兆位数据服务ＳＭＤＳ）。在２０世纪９０年代初,ＡＴＭ的部署数量明显提高。正...     

IP网络及其实时业务展望

本文讨论了目前通信领域的２个热闹话题：ＩＰ网的网络组成和ＩＰ网上的实时业务。关于ＩＰ网的网络组成,本文讨论了ＩＰｏｖｅｒ ＡＴＭ．ＩＰ ｏｖｅｒ ＳＤＨ和ＩＰ ｏｖｅｒ ＷＤＭ技术。关于ＩＰ网上的实时业务,本文讨论了ＩＰ电话、ＩＰ会议和ＩＰ网的信息点播业务。     

动态同步传送模式

在ＩＰ协议研究领域,人们在寻 找各种方法来拓展ＩＰ的应用范围,如 何高效传送ＩＰ包,提供实时业务和服 务质量（ＱｏＳ）保证,同时与传统电 信网集成,成为网络界和电信业共同 关注的一个焦点。自前,已提出的ＩＰ ｏｖｅｒ ＡＴＭ、 ＩＰ ｏｖｅｒ ＳＤＨ、 ＩＰ ｏｖｅｒ Ｏｐｔｉｃａｌ（ＷＤＭ）等各种解决方案正 在激烈的争论中。 ＩＰ ｏｖｅｒ ＡＴＭ由 于两种协议组合不够代化而降低了效 率。另一方面,随着密集波分复用 （ＤＷＤＭ）等光纤通信技术的发展, 带宽不断扩展的交换网络要求处理与 缓存的规模以指数级增长,使得Ｉ…     

IP over SONET和IP over ATM技术比较

简要介绍了ＩＰ ｏｖｅｒ ＡＴＭ和ＩＰ ｏｖｅｒ ＳＯＮＥＴ技术,如一般ＩＰ ｏｖｅｒ ＡＴＭ、局域网仿真、ＭＰＯＡ、多协议标记交换及ＩＰ／ＰＰＰ／ＳＯＮＥＴ等,并从协议开销、带宽管理、服务质量、地址和路由、多协议封装以及容错等几个方面对这两种机制进行了比较。最后,为网络管理员提供了部署这两种机制的几种相关方案。     

新一代综合业务信息网络体系ISIN技术的研究

随着Ｉｎｔｅｒｎｅｔ的深入应用和发展，各类新技术层出不穷，ＩＳＰ、ＩＣＰ、ＡＳＰ等网络公司不断涌现，推动着数据业务持续快事增长，数据业务有望在最近几年达到或超过话音业务。ＩＰ将成为未来信息通信的主导技术，各种业务可由ＩＰ来承载（Ｅｖｅｒｙ－ｔｈｉｎｇ　ｏｖｅｒ　ＩＰ），而ＩＰ信息流又可以在各种传输媒体中传送（ＩＰ ｏｖｅｒ Ｅｖｅｒｙｔｈｉｎｇ）。以ＩＰ网为基础，最终实现数据、话音、图象业务融合和网络融合，这已成为人们的共识。采用统一的技术解决方案（Ｉｎｔｅ－ｇｒａｔｅｄ　Ｓｏｌｕｔｉｏｎ）来构建…     

Data communication in ATM networks

An increasing number of customers require LAN access with high bandwidth and low delay over long distances. To satisfy these needs, several high-speed network techniques have been developed. Asynchronous transfer mode (ATM) is superior compared to other networking technologies, as it offers high bandwidth and is scalable in the sense that the bandwidth capacity of an ATM system is not fundamentally limited to the technology itself. Initial ATM installations will operate as subnetworks of existing networks and MAC layer protocols. One of the main challenges in ATM is the transparent support of existing connectionless LAN services. Several activities have been launched within international standard bodies and forums to specify ways of providing data communication services over ATM. Most notable examples are Switched Multimegabit Data Service (SMDS) and the similar Connectionless Broadband Data Service (CBDS) supported mostly by public network service providers. But also other approaches such as IP over ATM, and LAN emulation that show more adherence to the existing local and campus area networking paradigms. The article presents the requirements and architecture of the LAN emulation service. It describes the alternative methods for carrying IP packets over ATM, a public broadband service architecture and CBDS. The traffic management aspects of the data communication services are also discussed     

Efficient Distributed Bandwidth Management for MPLS Fast Reroute

As service providers move more applications to their IP/MPLS (multiple protocol label switching ) backbone networks, rapid restoration upon failure becomes more and more crucial. Recently MPLS fast reroute has attracted lots of attention as it was designed to meet the needs of real-time applications, such as voice over IP. MPLS fast reroute achieves rapid restoration by computing and signaling backup label switched path (LSP) tunnels in advance and re-directing traffic as close to failure point as possible. To provide a guarantee of bandwidth protection, extra bandwidth has to be reserved on backup paths. Using path merging technique as described in IETF RFC 4090 only, the network is able to share some bandwidth on common links among backup paths of the same service LSP, i.e., so-called intra-sharing. But no solution is provided on how to share bandwidth among backup paths of different service LSPs, i.e., so-called inter-sharing. In this paper, we provide an efficient distributed bandwidth management solution. This solution allows bandwidth sharing among backup paths of the same and different service LSPs, i.e., both intra-sharing and inter-sharing, with a guarantee of bandwidth protection for any single node/link failure. We also propose an efficient algorithm for backup path selection with the associated signaling extensions for additional information distribution and collection. To evaluate our schemes, we compare them via simulation with the basic MPLS fast reroute proposal, IETF RFC 4090, on two networks. Our simulation results show that using our bandwidth management scheme can significantly reduce restoration overbuild from about 250% to about 100%, and our optimized backup path selection can further reduce restoration overbuild to about 60%.     

RSVP在数字视频网络传输中的应用研究

数字视频网络的广泛应用,要求实时性传输中IP能够提供足够的带宽、较高的优先级以及较低的包丢失率,为此,Internet工程任务组(IETF)开发了一套用于因特网的综合服务协议和标准,通过RSVP来管理网络资源分配以提供不同级别的服务,讨论怎样将该协议与典型的数字视频网络传输方案相结合,使现有支持QoS的网络可以达到更为稳定流畅的传输效果.     

IP增值业务网络中的问题及其解决方案

ＩＰ增值网络系统凭借先进的多媒体通信技术支撑及强大的市场竞争力迅速发展。解决其在发展中所面临的一些问题的关键就是要有一套完整的ＩＰ网络解决方案,以实现一个具有网管系统、帐务清算系统、计费系统、认证系统、业务运营系统等一整套功能体系的ＩＰ增值业务网络系统,以便为ＩＰ网络运营商创造更具市场活力和产品兼容性的网络运营环境。     

VoIP over DVB-RCS with QoS and bandwidth on demand

Motivated by the need for compliance/interoperability above the satellite-specific layers, this article proposes a consolidated approach for voice over IP over satellite networks based on the ETSI DVB-RCS standard. Voice communication is a real-time service that needs priority over other services in IP environments with limited bandwidth, such as IP satellite networks. Bandwidth utilization in such networks needs to be optimized in order to reduce service costs, and this requires the use of dynamic bandwidth allocation schemes. This article therefore addresses the role of bandwidth on demand in the optimization of bandwidth allocation for VoIP and assesses the impact of BoD mechanisms on voice quality. The trade-off between voice quality and bandwidth efficiency is investigated under different DVB-RCS-specific capacity request/allocation strategies, and it is demonstrated that DVB-RCS provides an efficient platform for integrated support for a variety of VoIP applications over satellite. The main contribution of this article consists of the identification of the mechanisms capable of responding to the key challenges raised by the VoIP application in the satellite environment.     

VoIP reliability: a service provider's perspective

Voice over IP services offer important revenue-generating opportunities, as well as many technical challenges in providing high-quality services. Users have come to expect highly available telecommunications services with high-quality voice. Service providers need reliable high-performance networks to meet user expectations, and must be able to guarantee performance and reliability to their customers. In converged voice and data networks, the network infrastructure must deliver very high quality and availability for some customer needs, while also providing low-cost high-capacity bandwidth for other needs. The use of quality of service mechanisms to provide prioritization for various traffic types is a key element needed for voice and data network convergence. However, it is not sufficient if the underlying networks are unreliable. The focus of this article is to address the reliability aspects of VoIP services, including the underlying IP networks.     

The interface between IP and WDM and its effect on the cost of survivability

A summary of research on survivable IP networks overlaid over WDM networks is presented. The WDM networks are part of optical transport service providers, who lease lightpath services to institutions with IP networks. The lightpath services realize IP links for IP networks, and they have different protection grades such as unprotected and protected. The research included considering new network survivability requirements and incorporating them into network design problems. The cost of survivable IP over WDM networks is compared over three scenarios. Each succeeding scenario has the WDM network provide more flexible services, and the IP and WDM networks become more integrated. We consider the problem of setting up lightpaths for an IP network so that the network will remain connected after a fiber link fault. Algorithms to find the lightpaths and minimize cost are given. The network costs under the three scenarios are compared by simulations.     

应用使能机制推动IMS与Internet的融合

电信网与互联网在带宽、业务和IP技术不断发展的推动下,商业模式和业务模式发生了巨大变化。如何在大带宽的时代为内容提供商提供真正增强业务体验的能力,成为运营商摆脱传统比特管道角色的重要课题。本文着重就这个问题进行深入分析,提供了IMS应用使能机制实现高效业务体验的思路,并就IMS业务能力的抽象给出了相应的模型。     

Resource Management for Virtual Private Networks

Virtual private networks (VPNs) have rapidly emerged as a leading solution for multi-site enterprise communication needs. Provider-managed solutions modeled on RFC 2547 serve as a popular choice for layer 3 VPNs, and the hose model has emerged as a common and simple service specification. It offers a hose of a certain contracted bandwidth to customers. With the growth in size and number of VPNs and the uncertainties in the traffic patterns of customers, providers are faced with new challenges in efficient provisioning and capacity planning for these networks and satisfying customer service level agreements (SLA). We suggest that a set of techniques can be used to help the provider build an adaptively provisioned network. These techniques involve continually processing measurement information, building inferences regarding VPN characteristics, and leveraging them for adaptive resource provisioning. We developed scalable techniques to infer VPN characteristics that are important for provisioning tasks. We demonstrated the feasibility of such provisioning techniques with existing measurement obtained using SNMP infrastructure from a large IP/VPN service provider. Our examination of measurement data yielded interesting new insights into VPN structure and properties. Building on our experience with analyzing VPN characteristics, we articulate an adaptive provisioning architecture that enables providers to effectively deal with the dynamic nature of customer traffic     

Storage area network extension solutions and their performance assessment

Several solutions are proposed to extend storage area networking solutions over distances of hundreds to thousands of kilometers. Native fibre channel or end-to-end fibre channel-based solutions can be offered over long distances using SONET-based networks. Protocols such as Internet SCSI (iSCSI), Internet fibre channel protocol (iFCP) and fibre channel over TCP/IP (FCIP) are being proposed to enable storage area networking solutions over networks that use IP as their transport protocol. Performance analysis of these solutions in terms of application throughput under variable network conditions of packet loss, bandwidth availability, extension distance, and TCP implementations in the sender and receiver is presented based on analytical modeling of different solutions.