通信工程文献翻译——IP网络，爱与痛的边缘 

IP网络不仅可以承载各类业务，而且传送成本要远远低于基于电路交换的传统电信网。运营商可以借助这些业务的发展契机，在IP网络上开发更多具有含金量的新型业务。因此，随着电信网络的IP化趋势越来越明显，越来越多的运营商已经启动了网络升级换代的计划，期望通过网络的变革，为业务转型作好支撑。但是，要通过IP网络统一承载NGN、3G、IPTV、P2P等各种电信业务，运营商必须解决现有IP网络在业务的安全性、可靠性、服务质量以及可运营性等方面的一系列问题。 

面向将来的多业务IP承载网必须是一张商业网络，在可运营和可靠性两个方面能够与传统的电信网相比，包括：它首先需要具备丰富的实时、非实时业务提供能力，各类基于IP的业务终端可随时、随地、随意地接入网络；其次，还必须能识别业务，对每种业务或应用可依照商业契约关系，实现针对业务或应用进行差异化收费；再有，承载网资源可根据业务需求进行动态分配与回收，为电信级业务提供网络资源保障；最后，还必须通过各种手段，保证电信业务的安全性和可靠性。 

面向未来的多业务IP承载网必须是一张面向公众开放的、具有多业务提供能力的网络，能够接入各类业务终端，但各类终端基本上是不可信任的。因此，网络必须有能力对终端的身份进行鉴别，防止仿冒，可以控制终端对网络和其它终端的访问能力和权限，防止各类攻击的发生和业务的盗用，确保终端能够按照其定义的业务范围有序地通过网络获取其业务。IP网络从简单的互联网络向高可靠、高安全的电信级网络转变是网络转型的必然要求。 

面向未来的多业务IP承载网不仅要保证业务的安全，还要确保多业务的电信级、可管理和可运营能力。目前的IP网络是“尽力而为”的，在整个网络设计过程中，业务与承载分离，状态由终端维护；承载网不能感知业务，无法根据具体的业务要求调配网络资源，无法针对性地提供服务质量保证，因此也无法根据业务进行差异化的服务和收费；由于用户终端可信度差，基于终端提出的业务需求来实现网络资源的分配，势必造成网络资源的无序竞争，无法对用户和业务形成有效的服务契约。而面向未来的多业务IP承载网必须支持契约机制，即一旦接纳就必须按承诺提供有保障的服务。特别是在承载实时的话音和视频业务时，必须考虑在IP网络中引入电信级的控制机制，通过独立的承载（资源）控制层对业务的Q0S资源请求进行处理，实现基于业务的Q0S保证和管理。

MSCG成就IP网络简约之美 

为了解决目前网络结构不能适应IP网络转型所面临的问题，可以采用图1所示的网络结构，整合、优化现有网络资源，统一核心层和传送层，拓展接入层的网络融合以及业务融合能力，形成扁平化的网络架构，使独立分离、层级繁多的复杂网络向功能融合、架构扁平、用户和业务可控的简单网络转变，同时，在网络中部署业务控制节点，在网络边缘对各类业务进行合法性检验、业务感知和区分服务，使之具备强大的综合业务支撑和运营管理能力。 ......

A Perfect IP Network Still has a Long Way to Go 

IP networks possess many advantages making them an extremely attractive network option. Firstly, they provide a rich array of customized services and applications allowing users to enjoy media    communications, digital entertainment and the availability of a wealth of information. Secondly, IP networks transmission costs are considerably lower than those of circuit switching-based networks. Thirdly, the unprecedented flexibility of IP networks allows carriers to develop and deploy new services and assist carriers' transformation to integrated information service providers. 

Telecom services have increasingly adopted IP features, leading carriers to launch network upgrade projects aiming to replace traditional networks with IP networks. Carriers expect that doing so can support service transformation, but current Internet-based networks cannot in fact offer sufficient security, reliability, Q0S and operability for telecom services. In short, they are inadequate in terms of supporting complete telecom transformation. 

It is essential that future-oriented multi-service IP bearer networks offer operability, security and reliability that equal traditional networks. This covers a range of tasks and capabilities: providing a full range of real and non-real-time services; ensuring access flexibility for IP-based service terminals; facilitating service identification and differentiated billing according to business agreements; the ability to allocate, reclaim and guarantee network-wide resources in line with telecom service requirements, and ensuring telecom services' security and reliability. 

Such a network should balance openness and security. Public access at service terminals cannot guarantee 100% proper usage, and thus the network must be able to authenticate the identity of each terminal and mitigate any potential illegal use. This involves controlling a terminal's authority and function protocols in terms of how it relates to other terminals and the network. Illegal service use and network attacks must be prevented by ensuring that each terminal receives services as per its defined service scope. 

At present, the effective management and operational capabilities necessary for carrier-class telecom services cannot be guaranteed in IP networks, and the introduction of carrier-class control systems is essential. In the current 'best effort' IP model, services are separated from the bearer layer, meaning the bearer network can neither sense services nor request service-specific resource allocation. Moreover, the bearer network cannot provide Q0S guarantees, or differentiated services and billing modes. Public user terminals are open to misuse, and resource allocation tends to devolve into competition ......