MPLS and traffic engineering in IP networks

Rapid growth and increasing requirements for service quality, reliability, and efficiency have made traffic engineering an essential consideration in the design and operation of large public Internet backbone networks. Internet traffic engineering addresses the issue of performance optimization of operational networks. A paramount objective of Internet traffic engineering is to facilitate the transport of IP traffic through a given network in the most efficient, reliable, and expeditious manner possible. Historically, traffic engineering in the Internet has been hampered by the limited functional capabilities of conventional IP technologies. Recent developments in multiprotocol label switching (MPLS) and differentiated services have opened up new possibilities to address some of the limitations of the conventional technologies. This article discusses the applications of MPLS to traffic engineering in IP networks     

Network high availability for ethernet services using IP/MPLS networks

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

ATM网络抗毁和自恢复技术研究

基于ATM/MPLS技术的通信网络是承载宽带多媒体业务的综合平台。为了对承载业务进行抗毁保护,对ATM的最基本的1+1、1∶1、m∶n抗毁保护结构进行了研究和总结。同时结合网络传输层,如:PDH、SDH、WDM、MPLS的保护和应用层业务,如:IP、电路交换、以太网和帧中继的抗毁迂回策略,提出了ATM的多层次抗毁自恢复组网结构,为ATM的应用研究提供了借鉴。     

Unified control infrastructure for carrier network evolution

Migration strategies for the network control infrastructure are discussed, to evolve carrier networks toward an optical transport backbone optimized for IP traffic. The strategies presented aim to protect carriers' investments in their current multiservice and IP-routed networks, while expediting the backbone migration toward a unified packet-over-optical core for IP and multiservice transport. This unified core network simplifies the network layers and control systems, and consolidates data and multiservice traffic to reduce network cost with improved bandwidth efficiency. The network control system, including signaling, addressing, and routing, is analyzed in detail to demonstrate the feasibility of the proposed infrastructure. Built on multiprotocol label switching (MPLS) technology, the presented solutions take phased evolution steps to reduce network cost, improve bandwidth efficiency, and offer practical options for internetworking during the migration. These solutions provide carriers with competitive advantages to consolidate multiple services onto an IP-centric optical transport network. The unified control infrastructure not only offers flexible options for network upgrade with reduced network management overhead, but also supports enhanced networking and traffic engineering capabilities to ensure no compromise in the service level agreement committed to end customers.     

Service convergence using MPLS multiservice networks

Enterprises are increasingly using virtual private networks to interconnect remote sites. Traditionally, service providers have used ATM core networks to deliver layer 2 services such as frame relay, ATM, or TDM private lines, which enterprise customers have then used to build their corporate network infrastructure. Such services account for the majority of data service revenues today. However, pressure has increased on service providers to combine increased flexibility with reduced costs in the context of a highly dynamic telecommunications market. Service providers also need to generate new revenues from their IP network infrastructure, through new opportunities such as IP VPNs and virtual private LAN services, while simultaneously achieving operational efficiencies through the convergence of all of their services on a common MPLS backbone. New access and metro network technologies, such as Ethernet, are also emerging that can be used to deliver these new services to enterprise customers alongside ATM and frame relay access. This must be achieved while also supporting existing technologies such as ATM, which continue to deliver highly profitable services. This article discusses the technical challenges in meeting the often conflicting requirements of delivering both traditional layer 2 services and new layer 3 services on a converged MPLS network. We show how both network and service interworking are required, and how these must operate at the user, control, and management planes to enable profitable services to be delivered over the new converged network. The different solutions being defined in the standards bodies are described, and the distinct scenarios they address are explained.     

MPLS在基于SDH的3G接入网中的应用

以WCDMA为例,目前可商用的R99和R4版本都采用ATM承载技术,很多以SDH传输网作为传送平台的大型移动通信运营商采用基于SDH透传的MSTP技术从TDM向ATM平滑过渡,而未来的3G网络将发展成为从接入网到核心网全面采用IP承载的网络,考虑到IP网络在流量控制、QoS等方面的局限性,基于MPLS技术的IP承载将得到广泛的应用.但对于基础传输网络为SDH网络的运营商而言,不可能新建一个全新的纯MPLS网络来究成接入网向IP承载的过渡,必须以现有的SDH网络或MPLS网络为基础进行平滑过渡.讨论了3G接入网的IP演进进程中,MPLS在SDH传输网中的应用方案.     

Layer 3 VPN Services over IPv6 Backbone Networks: Requirements, Technology, and Standardization Efforts

Layer 3 virtual private networks (L3VFN) enable organizations to connect geographically dispersed sites to one another across the packet switched network of a service provider. The most popular form of L3VPN is based on BGP/MPLS (border gateway protocol/multiprotocol label switching) technology in which the service provider offers a network-based IP VPN routing and forwarding service to its customers across its own IPv4-based MPLS backbone network. With the deployment of IPv6-based backbone networks underway, there is an emerging requirement to support these same L3VPN services across a native IPv6 backbone network. This introduces a requirement to provide routing and tunneling of IPv6 VPN (and IPv4 VPN) packets across an IPv6 backbone network. Softwires is an Internet Engineering Task Force (IETF) Working Group chartered to address the requirement of providing a generalized, network-based, multi-address family, IP routing and tunneling capability across native IP backbone networks pursuant to IPv6 transitions. Elements of the softwires work can form the basis of an L3VPN over IPv6 solution. After providing a brief overview of how L3VPN works in various topologies, this article presents the requirements for L3VPN services over an IPv6 backbone network and discusses a possible solution set that builds over the softwire technology and related IETF standards. Finally, we outline future directions and how the softwire technology can support new services and improved scalability     

Internet performance monitoring

The growing diversity of services in the Internet is motivating research to improve measurability of traffic and Internet performance. This paper surveys current projects and tools for Internet performance monitoring, ranging from passive router-based traffic flow measurement methods to large-scale active performance monitoring projects. The tools and methods are discussed according to their protocol layer, starting from the network layer (ATM, MPLS) to IP/ICMP and transport/application layers. At each protocol layer the strengths and limitations of the methods are highlighted. Finally, issues and challenges for future research are reviewed     

Technologies for DVB Services on the Internet

In 2004 DVB approved the first edition of the DVB IP Handbook, intended to support the first commercial deployments of Internet TV services. The specifications in the handbook standardize technologies at the receiver interface, to enable TV, radio, and general interactive multimedia services over IP-based networks. This paper gives an overview of the specifications, beginning with the reference architecture currently used by DVB. The key technologies specified are service discovery and selection, a DVB Real-Time Streaming Protocol client, MPEG-2 transport over IP, IP address allocation and network time services, receiver identification, and a network provisioning option.     

IP switching for scalable IP services

Internet protocol (IP) switching is emerging as a critical technology for improving the speed and scalability of the Internet. This paper discusses IP Navigator, a form of IP switching developed specifically for use in core network backbones, such as Internet service provider networks and major corporate backbones. IP Navigator combines the high speed and quality of service capabilities of asynchronous transfer mode (ATM) with the scalability and flexibility of IP. This paper presents an overview of the techniques that have been developed for operating IP over ATM. We outline the IP Navigator design and compare IP Navigator with other IP switching approaches     

The building blocks of a data-aware transport network: deploying viable Ethernet and virtual wire services via multiservice ADMs

SONET/SDH technologies constitute the core transport infrastructure of major telecom service providers worldwide. As the percentage of packet-oriented traffic in the overall traffic demand continues to rise, prompted by the widespread adoption of the Internet protocol suite, and recently by the fast adoption of Ethernet services, there is increasing pressure to improve the service provider's transport infrastructure in ways that make it data-aware and cost-effective for packet-oriented applications. Steps in this direction include the adoption of native physical interfaces, for Ethernet and storage area networks as service interfaces, or full integration of packet switching capabilities from Ethernet, resilient packet ring, and MPLS technologies. This article discusses the emerging building blocks for next-generation data-aware transport networks and next-generation transport network elements.     

Multi-Protocol Label Switching as the Basis for a Converged Core Network

This paper addresses the requirements and issues surrounding the carriage of existing and future services over a multi-protocol label switching (MPLS) core network. It provides an overview of MPLS, describing how MPLS is already being used to support VPN services offering support for multiple qualities of service. It discusses the requirements of future core networks and assesses how MPLS can be used to meet them. Finally it identifies a number of areas where BT is actively working to enhance the capability of MPLS to support future multiservice core network architectures.     

Broadband satellite networks-the global IT bridge

Next-generation broadband satellite networks are being developed to carry bursty Internet and multimedia traffic in addition to the traditional circuit-switched traffic (mainly voice) on a global basis. These satellites provide direct network access for personal applications as well as interconnectivity to the terrestrial remote network segments. The main requirement in success of these networks is that they should be able to transmit high data rate traffic with prescribed quality of service (QoS). Thus, the broadband satellite network has no choice other than the rise of ATM technology and to be optimized for Internet-based traffic. ATM is the promising technology for supporting high-speed data transfer potentially suitable for all varieties of private and public telecommunications networks. IP, on the other hand is the fast-growing Internet layer protocol that is applicable over any data link layer Internet-based applications are the emerging source of traffic in the future wireless networks and broadband satellite networks should consider Internet as the primary service. In this paper, we discuss the traditional ATM and wireless ATM networks and explain the characteristics of the wireless IP networks. The paper then uses those concepts in defining the criteria for the broadband satellite networks such as the QoS and traffic management. Application of the broadband satellite networks is also proposed     

Design and implementation of an RSVP-based quality of servicearchitecture for an integrated services Internet

The Internet Engineering Task Force (IETF) is currently in the process of overhauling the architecture of the Internet to meet new challenges and support new applications. One of the most important components of that venture is the enhancement of the Internet service model from a classless best effort service architecture to an integrated services architecture supporting a multitude of classes and types of services. This paper presents the design, implementation, and experiences with a protocol architecture for the integrated services Internet. It is based on the emerging standards for resource reservation in the Internet, namely, the RSVP protocol and the associated service specifications defined by the IETF. Our architecture represents a major functional enhancement to the traditional TCP/IP protocol stack. It is scalable in terms of performance and number of network sessions, and supports a wide variety of network interfaces ranging from legacy LAN interfaces, such as Token Ring and Ethernet, to high-speed ATM interfaces. The paper also describes the implementation of this architecture on the IBM AIX platform and our experiences with the system. We then present a performance analysis of the system which quantifies the overheads imposed by all components of the QoS support, such as traffic policing, traffic shaping, and buffer management     

WCDMA核心网信令系统对七号信令网的影响

BICC和GCP是第三代移动网络中必不可少的信令,主要支持的承载网络是ATM和IP,许多厂商也侧重开发ATM和IP传输技术。在中国未来几年逐渐开展3G移动业务后,GSM网络的业务也可以逐渐连接到3G核心网络中,GSM也会支持分层网络,使用比STM更经济的IP作为传输,原来七号信令网络中的流量就会逐渐减少。在设计3G七号信令网络时,需要考虑3G网络信令对传输的要求,为将采用的新技术进行准备。     

Multilayer traffic engineering for multiservice environments

Multilayer traffic engineering (MLTE) serves to provide cross-layer online network optimization techniques to cope with rapid variations and short-term evolutions in traffic patterns. MLTE extends traffic engineering as it exists in IP/MPLS-based technology toward the multilayer IP/MPLS-over-optical transport network. In addition to the IP/MPLS traffic routing, MLTE exposes much larger adaptation flexibility by building on next-generation automatic switched optical transport networks. These offer fast setup and teardown of end-to-end multi-hop optical connections (lightpaths), which are offered to the IP/MPLS layer as dynamically provisioned capacity. This dynamic nature leads to an IP/MPLS logical topology that can be reconfigured on the fly, and IP/MPLS link capacity that can be up- or downgraded as client traffic demand varies. These MLTE techniques are generally used to increase perceived network performance in terms of throughput or QoS. As such, a MLTE-managed network offers a better than best-effort service. Many types of traditional and novel services are shifting toward IP/MPLS technology. Consequentially, MLTE algorithms and strategies should be conceived with the characteristics of such services in mind. We present a MLTE strategy that can be implemented in a robust and distributed way. This strategy is then taken as the starting point in a study which evaluates its suitability to such services. We show how the strategy can be adapted considering service performance metrics such as end-to-end delay, traffic loss, and routing stability, and how such service optimizations impact general MLTE objectives such as IP/MPLS logical topology mesh size reduction.

利用多协议标记交换技术实现IP网的流量工程

文章概述了基于集成模式的新一代技术——多协议标记交换技术(MPLS)产生的原动力及其良好的应用前景,并通过对IP网络中流量工程技术发展阶段的分析,比较了各种流量工程技术的差异及优缺点,重点研究了基于MPLS技术实现IP网络中流量工程的工作原理,并以深训市IP城域网为例作了具体说明。     

网络融合的趋势分析和展望

下一代网络业务、控制、承载、接入分离的思想为未来网络融合提供了统一的架构。网络融合包括业务融合、核心网络融合、接入网络融合、终端融合、运维融合等多个方面。未来融合网络的发展趋势将是在核心控制层采用IP多媒体子系统(IMS),在核心承载层采用因特网协议/多协议标记交换(IP/MPLS)技术,在业务层采用统一开放的业务提供架构,在接入层支持固定、移动、窄带、宽带等多种接入技术,终端则呈现多模化和智能化的趋势,最终实现一个用户、一个号码、一个终端、一个账单、一个核心网络、随时随地享受的全业务模式。     

基于MPLS的移动IP研究

MPLS和移动IP结合技术是目前网络技术研究中的一个热点和难点,将MPLS与移动IP技术进行有机的结合,可以提高网络数据的交换传输速度,支持主机自由访问因特网,增强对QoS的支持,提高网络的安全性能.首先对移动IP技术和MPLS的基本工作原理进行了介绍,给出了基于MPLS标记交换路径的移动IP网络模型,提出多MPLS网络方案以及基于MPLS网络的IP路由优化方案,并对各方案的工作原理以及存在的问题进行了阐述,最后指出了需要进一步研究的问题.     

Internet QoS路由与业务工程

本文阐述了传统ＩＰ路由协议存在的问题,回顾了ＱｏＳ路由技术在电路交换网络,ＡＴＭ网络和ＩＰ网络中的演进与应用。论述了业务工程在Ｉｎｔｅｒｎｅｔ中的基本功能,以及与之相关的约束路由和ＭＰＬＳ技术。