ASON自动交换光网络简介
一、 前言
通信网络的发展从PDH算起，经过SDH/SONET/OTN到现在的ASON自动交换光网络已是第三代，它充分反映了光通信网从低速链路到高速、超高速，从点对点拓扑到环、MESH，从低速电复用到高速电复用、光复用，从主要面向链路、网元的管理到面向端到端服务的管理的演进趋势。
今天，支持ASON已经成为光设备厂商宣传推广其光设备的必要条件，尤其在中国，随着AT&T采用Ciena推出的智能光设备，AlCAtel在北京，Lucent在江苏部署智能光网络产品，国内运营商普遍表现出了对ASON的热烈欢迎，ASON之所以如此重要，获得运营商以及制造商的一致推崇，主要是源于：
(1)网络传送层面的技术已日趋成熟，包括虚级联，GFP(GenericFramingProcedure通用帧规程)，LCAS(LinkCapacity Adjustment Scheme链路容量调节方案)等新技术和RPR(Resilient Packet Ring弹性分组环)，MSPP/MSTP(Multi Service Provisioning Platform/Transport Platform多业务配置/传送平台)等新平台为语音/数据网络融合提供了多种选择;
(2)不论采用何种产品或平台，运营商对降低网络运营、维护的复杂度，减少网络故障率，提高资源有效利用率和比对手更快速推出新型、灵活的带宽业务一直是最渴望的;
(3)ASON为各种网络设备提供了统一的控制、管理平台，技术上为制造商提供了促使光网络智能化的有力工具，同时充分考虑了如何满足运营商的需求。
二、ASON技术特性与协议标准
1.ASON组成与服务
ASON主要由以下三个独立的平面组成，即传输平面、控制平面和管理平面。(还有一个不常提及的DCN面用来承载控制信号)。类似ATM，ASON支持三种连接，即永久连接PC(PermanentConnection)、交换连接SC(SwithchedConnection)和软永久连接SPC(SoftPermanent Connection)。永久连接也被称为定制连接，由网管系统或者由人工完成，而交换连接是信令驱动的连接，终端用户根据需要，可在任意两个连接端点间建立连接。SPC与PC连接都是由管理平面发起的连接，不同之处在于光网络内部是使用信令还是利用网管接口。光网络内部使用信令建立连接时，涉及到控制面内的信令部分，每个网元的控制实体相互之间需要动态交互信令信息，另外控制面内的路由部分也要在实体之间交换路由信息。信令建链需要网络命名和寻址(Naming and Addressing)策略的支持。
2.ASON接口定义与网络协议族
由于AS0N在网络架构上属于层叠模型(OverlayModel)，ASON网络逻辑上分为UNI(UserNetworkInterface用户网络接口)，I-NNI(Inter-Network Network Interface内部网络-网络接口)和E-NNI(Exterior-Network Network Interface外部网络-网络接口)三个部分。
UNI主要运行在光网络客户端和光网络设备之间，是业务请求者和业务提供者控制平面实体间的双向信令接口，主要功能是完成二者间的连接建立、连接拆除、连接修改、状态查询，相互之间不交换路由信息，可选的功能有邻居发现，服务发现等。UNI1.O版主要针对SDH接口，在下一版UNI2.O中会加上对以太网的支持。UNI2.0对信令的信息完整性、安全性等方面也比1.0有了较大的关注。目前UNI有三种侯选协议：PNNI(专有网络-网络接口
PrivateNNI)，CR-LDP(约束路由的标签分发协议ConstrainedRouting-LabelDistribution Protocol)和RSVP-TE(资源预约协议带流量扩展Resource Reservation Protocol--Traffic Extension)。
I-NNI是属于一个域内的控制平面实体间的双向控制接口。由于在域内运行，一般是同一个设备商的设备，因此没有建议标准化，每个设备厂商可以使用专有的接口协议也可以使用众所周知的接口协议。I-NNI接口使用协议包括路由协议和信令协议，路由协议可以是OSPF-TE(开放最短路径优先协议-带流量工程扩展OpenShortestPathFirst-Traffic Engineering)、IS-IS-TE(中间系统-中间系统路由协议-带流量工程扩展Intermediate System-Intermediate System-Traffic Engineering)或BGP(边界网关协议Border Gateway Protoco1)协议，信令协议主要是CR-LDP和RSVP-TE。
E-NNI是属于域间控制平面的不同实体间的双向控制接口，支持呼叫控制、资源发现、连接控制、连接选择、连接路由选择。与I-NNI不同，它是在不同域间交换路由可达性信息，屏蔽了网络内部的拓扑信息。对多层拓扑结构间的E-NNI信息交互尤其是标准化的难点和重点。
ASON主要由三个国际化标准组织在推进，IETF,OIF和ITU-T。
(1)IETF
IETF的MPLS，到GMPLS是催生ASON产生的基础。ASON使用的信令协议CR-LDP，RSVP-TE都是IETF近来标准化的结果，而ASON的路由协议包括OSPF-TE，BGP，它们都在原先协议的基础上，对光网络发展的需求做了相应的扩展。最新增加的LMP链路管理协议也在不断修订中。
(2)OIF
OIF对ASON最值得肯定的工作是UNI1.0。由于有了UNI1.0，数据设备厂商和电信设备厂商在设备自动化互联时有了充分可信赖的依据。现在有了UNI1.0的第二版，还有正在标准化中的，引入了以太网业务，支持带宽动态改变的UNI2.0。0IF另一个重点研究的领域是E-NNI，力图在设备域间互联上提供互联互通的可能。
(3)ITU-T
ITU-T的优势是在协议框架搭建，网络管理和业务提供方面，依照ITU-T的建议，ASON只支持层叠模型，定义了G.8080/Y.ASON结构，区分了呼叫和连接，用抽象模型抽象化了信令协议，提出了路由协议的需求，支持DCN细化为SCN(信令连接网SignalingConnectionNetwork)和MCN(网管连接网ManagementConnection Network)仔细考虑了ASON网管的问题。
3.ASON技术优势
与现有的SDH组网技术相比，ASON有以下优点：
(1)统一的分布式控制/管理层面，与底层的物理实现技术无关，理论上讲支持各种带宽粒度的交换和管理，无论是IP路由器，ATM交换机还是光交叉连接设备都可以应用;
(2)快速的定制支持不同SLA(ServiceLevelAgreement)级别电路，不仅缩短了业务提供时间，提高了网络资源的利用率，还可提供新的带宽业务，如BODS(按需带宽服务)，OVPN(光虚拟专用网)等;
(3)支持端到端的连接建立、监控、保护和恢复，对各种网络拓扑结构，包括网状网的支持，增强了网络的流量工程能力。
三、ASON市场未来预测
在ASON出现之前，DWDM技术以满足Gilder定律的方式，每六个月翻一番的增长趋势极大地改善了骨干网长途链路上容量短缺的问题，不需要铺设新光纤，只需要增加波长路数，
运营商就可以充分满足巨量带宽的需求，带宽的极大丰富并不意味着运营商可以迅速满足用户对带宽需求的响应，在网络流量日趋数据化，突发性更大的背景下，对多粒度，动态带宽改变，迅速部署电路的强烈需求使得ASON日益重要和普及。当前市场上已经有Ciena、华为、中兴、朗讯、阿尔卡特等众多厂商宣称支持ASON的设备可供选择。在可预见的未来，ASON在以下四个方面将有极大的市场需求。
1.城域传送网的换代升级ASON+MSTP
在业务模式更加数据的今天，传统的SDH根本无法适应数据业务的需求，而基于SDH发展起来的MSTP(多业务传送平台)正在成为新一代城域网建设的首先技术。因为发展业务的需要，ASON与MSTP结合，由MSTP提供下层的物理传送通道，由ASON完成网络智能的控制和管理是未来必然的选择。
2.长途传送网的灵活波长业务
在长途骨干传输网上，配置灵活的波长上下路(如通过可重构光上下路复用器(R-OADM)，波长扩容或者长途干线链路保护/恢复，可以由ASON的分布式智能控制来提供，加上提供超长距离传输的ULH技术，长途大容量的实时电路指配、调度和保护可以在几分钟之内完成，极大地削减人工配置电路的复杂性、易错性和不灵活性。
3.对城域接入的支持如3G基站、企业网边缘路由器、网关、IAD等 新一代的MSTP除了原来的SDH接口，增加了对以太、MPLS甚至RPR(弹性分组环)接入的支持，考虑到未来无线3G应用的宽带需求，例如3G基站之间的互联，企业网络设备的速率升级，利用ASON为用户提供安全高速的二层VPN或者一层VPN满足互联需求是未来可预见的有吸引力的新业务。
4.对NGN的支持
NGN是下一代的未来通信网络，是基于分组的，基于控制与呼叫分离的，呼叫与承载分离的软交换、业务驱动型的，开放型的网络架构体系。ASON从本质上讲，它在业务传送环境里采用的交换技术不是分组，而是电路型的，但是它本身是和设备的物理传输/交换技术独立的，而且满足两个分离的特性，对将来的业务是开放的。ASON必然要符合NGN的框架约定，而且应是满足这个约定的重要的示范网络。
四、ASON局限性
迄今为止，还没有任何一项技术可称为完美无缺的，正在发展中的ASON也是一样。ASON的缺陷主要存在于：
1.标准有待完善
ASON的标准到目前为止有很大的进展，但是在互联互通，网络管理和管理平面本身的健壮性等方面还有许多工作要做。而且由于是多个标准化组织在参与，标准的沟通工作也比较麻烦。
2.测试设备不成熟
设备的成熟首先要依赖测试设备的成熟，当前号称推出GMPLS/ASON协议测试的公司，实际上都还没有成熟定型的产品推出，受标准不断更新的影响，也很难在当前拿出实际的产品。
3.流量工程、保护/恢复等特色功能的有效性
运营商在运行网络时，对实时监控能力、优化网络，提高网络的生存性永远是不断的追求，ASON号称可以解决这些问题，可是其真实有效性还没有经过真正的大规模网络现场测试，究竟是彻底解决问题还是仅仅减轻问题还没有也暂时不可能定论。
4.新业务的支持
ASON支持的业务种类很多，如SDH、OTN、以太网、存储网等，它对新业务也具有扩展性，其实ASON主要就是推销可快速部署的带宽，无论是波长出租，波长拨号，OVPN等都是如此。ASON宣称支持可保证QoS或者SLA的业务连接，包括点到点单向/双向连接，点到多点的单向连接。但是对后者，象在IP网中一样的多播机制(Multicast)还没有明确定义出来并加以验证，因此对某些应用，如观众所在地域分散的视频广播还没有特别高效的节省带宽的办法。
5.综合网管
ASON提供了新的网络控制管理平台，当然满足TMN的框架，但并不是排斥或完全代替已有的传输网网管系统，或者ATM网管，在涉及到底层的管理时还要与现有管理系统的相互配合，集成，在实际运营时，会产生比较繁琐的问题。
（英文版见下页）
About ASON Automatic Switched Optical Network
Frist,Preface
The development of modern optical communication networks counting from the PDH, through SDH / SONET / OTN to ASON now automatically switched optical network is the third generation, which fully reflects the optical communication network links from low to high speed, ultra-high speed, from the point point topology to the ring, MESH, from the low-speed electric power used in most high-speed multiplexing, optical multiplexing, from the main for the link, network element management to-end service management for the evolution of trends.
Today, support for ASON has become the optical equipment manufacturer promotion of their optical equipment necessary conditions, especially in China, with AT & T using Ciena introduced intelligent optical equipment, AlCAtel in Beijing, Lucent in Jiangsu deployment of intelligent optical networking products, domestic operators generally showed a warm welcome to the ASON, ASON is so important, operators and manufacturers to obtain unanimous praise, primarily because of:
(1) network transmission level technology has matured, including Virtual Concatenation, GFP (GenericFramingProcedure common frame of order), LCAS (LinkCapacity Adjustment Scheme link capacity adjustment scheme) and other new technologies and RPR (Resilient Packet Ring Resilient Packet Ring), MSPP / MSTP (Multi Service Provisioning Platform / Transport Platform Multi-service configuration / delivery platform) and other new platforms for voice / data network convergence to provide a variety of options;
(2) Regardless of the product or platform, network operators reduce operating, maintenance complexity, reduce network failure rate and improve the effective utilization of resources and faster than your opponents launched a new, flexible bandwidth service has been the most desired ;
(3) ASON for a variety of network equipment provides a unified control and management platform for the manufacturers to provide a technically led a powerful tool for intelligent optical networks, taking full account of how to meet the needs of operators.
Second, ASON technology features and protocol standards
1.ASON components and services
ASON mainly by the following three separate planes, namely, the transport plane, control plane and management plane. (There is also a rarely mentioned in the DCN surface to carry
control signals). Similar to the ATM, ASON supports three connections, namely, a permanent connection PC (PermanentConnection), switched connection SC (SwithchedConnection) and soft permanent connection SPC (SoftPermanent Connection). Permanent connection is also known as custom connected by network management system or by hand to complete, and switched connection is a connection-driven signaling, end-users as needed, can be established between any two terminals connected. SPC and PC connections are initiated by the management plane connection, the difference is within the network is to use optical signaling, or by network management interface. Optical network signaling to establish a connection for internal use when it comes to the control plane signaling part of the controlling entity of each network element requires dynamic interaction between the signaling information, the other part of the routing control plane also in the entities exchange routing information. (Naming and Addressing) Construction chain requires signaling network naming and addressing (Naming and Addressing) policy support.
2.ASON interface definition and network protocol suite
As the network architecture is AS0N Overlay Model (OverlayModel), ASON network logically divided into UNI (UserNetworkInterface user network interface), I-NNI (Inter-Network Network Interface internal network - network interface) and E-NNI (Exterior-Network Network Interface external network - network interface) in three parts.
UNI main client running on the optical network and optical network equipment, and is the business of the requester and service provider control plane entities of the two-way signaling interface, the main function is to establish a connection between the two, the connection removal, connection changes, state query, do not exchange routing information between each other, optional features are neighbor discovery, service discovery. UNI1.O version mainly for SDH interface in the next version of UNI2.O will add support for Ethernet. UNI2.0UNI2.0 signaling information on the integrity, security and so on greater than 1.0 have concerns. Currently there are three candidates UNI protocol: PNNI (private network - network interface PrivateNNI), CR-LDP (constraint-based routing label distribution protocol ConstrainedRouting-LabelDistribution Protocol) and RSVP-TE (resource reservation protocol with flow expansion Resource Reservation Protocol - Traffic Extension).
Since the domain is running, usually with a device's device, there is no recommended standard, each device manufacturers can use the proprietary interface protocol can also use the well-known interface protocol. I-NNI interface using protocols including routing protocols and signaling protocols, routing protocols can be OSPF-TE (Open Shortest Path First Protocol - with traffic engineering extensions OpenShortestPathFirst-Traffic Engineering), IS-IS-TE (Intermediate System - Intermediate System Routing Protocol - with Traffic Engineering extensions Intermediate System-Intermediate System-Traffic Engineering) or BGP (Border Gateway Protocol Border Gateway Protoco1) protocol, signaling protocol is mainly CR-LDP and RSVP-TE.
E-NNI inter-domain control plane are different entities of the two-way control interface to support call control, resource discovery, connection control, connection options, connection routing. And I-NNI different, it is between the different domains exchange routing reachability information, shielding the internal network topology information. Multi-layer topology of the E-NNI between information exchange, especially the standardization of difficulty and focus.
ASON mainly by the three international standards organizations in promoting, IETF, OIF and
ITU-T.
(1) IETF
ASON signaling protocols used in CR-LDP, RSVP-TE is the result of IETF has recently standardized, and ASON routing protocols including OSPF-TE, BGP, they are in the original agreement, based on the needs of the development of optical network do be extended. The latest addition to the LMP Link Management Protocol are also constantly revision.
(2)OIF
Thanks UNI1.0, data equipment manufacturers and telecommunications equipment manufacturers in the interconnection of automation equipment have a full time basis trusted. Now, with UNI1.0 the second edition, there is standardization, the introduction of Ethernet services to support dynamic bandwidth change UNI2.0. 0IF Another key research area is the E-NNI, in a bid field equipment provide interoperability between the Internet possible.
(3)ITU-T
ITU-T the advantage of the framework agreement to build, provision of network management and operations, in accordance with ITU-T recommendations, ASON only supports cascading model, defined G.8080/Y.ASON structure, a distinction between call and connection, with the abstract abstract model of a signaling protocol, proposed routing protocol needs to support DCN subdivided into SCN (Signaling Connection Network SignalingConnectionNetwork) and MCN (network connectivity network ManagementConnection Network) careful consideration of the ASON network management issues.
3.ASON technical advantages
And compared with the existing SDH network technology, ASON has the following advantages:
(1) a unified distributed control / management level, and the underlying physical implementation technology has nothing to do, in theory, support a variety of exchange and management of the bandwidth granularity, whether IP routers, ATM switches or optical cross-connect devices can be applied;
(2) rapid customization support different SLA (ServiceLevelAgreement)-level circuit, not only shortened the time for service provision and improve network efficiency, bandwidth can provide new services, such as BODS (on-demand bandwidth services), OVPN (light Virtual Private Network), etc.;
(3) to support end to end connection establishment, monitoring, protection and recovery, on a variety of network topologies, including mesh networks to support and enhance the network's traffic engineering capabilities.
Third, ASON forecast the future market
Before the appearance of the ASON, DWDM technology to meet the way Gilder's law, doubling every six months, the growth trend has greatly improved the long-distance backbone network link capacity shortage problem, do not need to lay new fiber, only the large ones need to increase the wavelength , operators can fully meet the massive demand for bandwidth, the bandwidth of the great wealth does not mean operators can quickly meet customer demand for bandwidth in response to growing data traffic in the network of, a larger context of sudden,
multi-size, dynamic bandwidth changes, the strong demand for the rapid deployment of the circuit makes the ASON increasingly important and popular. The current market has Ciena, Huawei, ZTE, Lucent, Alcatel and other vendors claim to support ASON devices to choose from. In the foreseeable future, ASON in the following four areas will have great market demand.
1. The new generation metro transport network upgrade ASON + MSTP
More data in the business model today, the traditional SDH data services simply can not adapt to the needs of developed SDH-based MSTP (Multi-Service Transport Platform) is the first of a new generation of MAN technologies. Because the development of business needs, ASON and MSTP combination provided by the MSTP lower physical transmission channel, completed by the ASON network intelligent control and management of the inevitable choice for the future.
2. Long-distance transmission network service flexible wavelength In the long-distance backbone transmission line, flexible configuration, the wavelength of the upper and lower road (such as up and down through the reconfigurable optical multiplexers (R-OADM), wavelength expansion or long haul link protection / restoration, can be distributed intelligent control to ASON offer to provide ultra-long haul transmission with ULH technology, real-time long-distance high-capacity circuit assignment, scheduling, and protection can be completed in minutes, greatly reducing the complexity of manual configuration circuit, error-prone and non-flexibility .
3. To the metro access and flexible support, such as 3G base stations, enterprise edge routers, gateways, IAD, etc.
A new generation MSTP SDH interfaces in addition to the original, adds Ethernet, MPLS or RPR (RPR) access to support, taking into account the future demand for wireless 3G broadband applications, such as the interconnection between the 3G base stations, enterprise network equipment the rate of escalation, the use of ASON to provide security for the user, or a layer of high-speed Layer VPN Internet VPN to meet foreseeable future demand for attractive new business.
4. For the support of NGN
NGN is next generation communications network is packet-based, based on the separation of control and call, call and bearer separation of the soft-switching, business-driven, open network architecture system. ASON In essence, it is transmitted in the business environment is not used in packet switching technology, but the circuit type, and equipment, but it itself is the physical transmission / switching technology independent, but also to meet two separate properties, the future The business is open. ASON is bound to comply with the agreed framework of NGN, and should be agreed to meet this important demonstration network.
Fourth, ASON limitations
ASON defects mainly in:
1. The standard to be improved
ASON standards has seen much progress so far, but in the interconnection, network management and robust management plane itself, there is still much work to do so. And because it is involved in several standardization organizations, the standard of communication is also more trouble.
2. Test Equipment immature
Equipment, test equipment, mature first mature to rely on the current known release GMPLS / ASON protocol testing company, in fact, stereotypes are still not mature product launch, the impact of constantly updated by the standard, it is difficult to come up with actual product in the current .
3. Traffic engineering, protection / restoration of features such as the effectiveness of
Operators to run the network, real-time monitoring capability, optimize network, increase the survivability of the network is always constant pursuit, ASON known to solve these problems, but its effectiveness has not real large-scale network of genuine field test, whether is completely solve the problem or just temporarily alleviate the problem are not yet conclusive.
4. The support of new business
ASON supports many different types of business, such as SDH, OTN, Ethernet, storage, networks, etc., it also has a new business expansion, in fact, ASON is mainly selling to the rapid deployment of bandwidth, whether it is leased wavelengths, the wavelength dial, OVPN etc. This is true. ASON claims to support guaranteed QoS or SLA's business connections, including point to point one way / two-way connection, one-way multipoint connection. But the latter, as in the same IP network multicast mechanisms (Multicast) has not clearly defined and verified it, so for some applications, such as where geographically dispersed audience video broadcasting has not particularly efficient way to save bandwidth .
5. Integrated Network Management
ASON control provides a new network management platform, of course, to meet the TMN framework, but not exclusive or completely replace the existing transmission network management system, or ATM network, in relation to the management of the bottom also with the existing management system of mutual cooperation, integration, when in actual operation, will have more complicated problems.
ASON自动交换光网络简介
一、 前言
通信网络的发展从PDH算起，经过SDH/SONET/OTN到现在的ASON自动交换光网络已是第三代，它充分反映了光通信网从低速链路到高速、超高速，从点对点拓扑到环、MESH，从低速电复用到高速电复用、光复用，从主要面向链路、网元的管理到面向端到端服务的管理的演进趋势。
今天，支持ASON已经成为光设备厂商宣传推广其光设备的必要条件，尤其在中国，随着AT&T采用Ciena推出的智能光设备，AlCAtel在北京，Lucent在江苏部署智能光网络产品，国内运营商普遍表现出了对ASON的热烈欢迎，ASON之所以如此重要，获得运营商以及制造商的一致推崇，主要是源于：
(1)网络传送层面的技术已日趋成熟，包括虚级联，GFP(GenericFramingProcedure通用帧规程)，LCAS(LinkCapacity Adjustment Scheme链路容量调节方案)等新技术和RPR(Resilient Packet Ring弹性分组环)，MSPP/MSTP(Multi Service Provisioning Platform/Transport Platform多业务配置/传送平台)等新平台为语音/数据网络融合提供了多种选择;
(2)不论采用何种产品或平台，运营商对降低网络运营、维护的复杂度，减少网络故障率，提高资源有效利用率和比对手更快速推出新型、灵活的带宽业务一直是最渴望的;
(3)ASON为各种网络设备提供了统一的控制、管理平台，技术上为制造商提供了促使光网络智能化的有力工具，同时充分考虑了如何满足运营商的需求。
二、ASON技术特性与协议标准
1.ASON组成与服务
ASON主要由以下三个独立的平面组成，即传输平面、控制平面和管理平面。(还有一个不常提及的DCN面用来承载控制信号)。类似ATM，ASON支持三种连接，即永久连接PC(PermanentConnection)、交换连接SC(SwithchedConnection)和软永久连接SPC(SoftPermanent Connection)。永久连接也被称为定制连接，由网管系统或者由人工完成，而交换连接是信令驱动的连接，终端用户根据需要，可在任意两个连接端点间建立连接。SPC与PC连接都是由管理平面发起的连接，不同之处在于光网络内部是使用信令还是利用网管接口。光网络内部使用信令建立连接时，涉及到控制面内的信令部分，每个网元的控制实体相互之间需要动态交互信令信息，另外控制面内的路由部分也要在实体之间交换路由信息。信令建链需要网络命名和寻址(Naming and Addressing)策略的支持。
2.ASON接口定义与网络协议族
由于AS0N在网络架构上属于层叠模型(OverlayModel)，ASON网络逻辑上分为UNI(UserNetworkInterface用户网络接口)，I-NNI(Inter-Network Network Interface内部网络-网络接口)和E-NNI(Exterior-Network Network Interface外部网络-网络接口)三个部分。
UNI主要运行在光网络客户端和光网络设备之间，是业务请求者和业务提供者控制平面实体间的双向信令接口，主要功能是完成二者间的连接建立、连接拆除、连接修改、状态查询，相互之间不交换路由信息，可选的功能有邻居发现，服务发现等。UNI1.O版主要针对SDH接口，在下一版UNI2.O中会加上对以太网的支持。UNI2.0对信令的信息完整性、安全性等方面也比1.0有了较大的关注。目前UNI有三种侯选协议：PNNI(专有网络-网络接口
PrivateNNI)，CR-LDP(约束路由的标签分发协议ConstrainedRouting-LabelDistribution Protocol)和RSVP-TE(资源预约协议带流量扩展Resource Reservation Protocol--Traffic Extension)。
I-NNI是属于一个域内的控制平面实体间的双向控制接口。由于在域内运行，一般是同一个设备商的设备，因此没有建议标准化，每个设备厂商可以使用专有的接口协议也可以使用众所周知的接口协议。I-NNI接口使用协议包括路由协议和信令协议，路由协议可以是OSPF-TE(开放最短路径优先协议-带流量工程扩展OpenShortestPathFirst-Traffic Engineering)、IS-IS-TE(中间系统-中间系统路由协议-带流量工程扩展Intermediate System-Intermediate System-Traffic Engineering)或BGP(边界网关协议Border Gateway Protoco1)协议，信令协议主要是CR-LDP和RSVP-TE。
E-NNI是属于域间控制平面的不同实体间的双向控制接口，支持呼叫控制、资源发现、连接控制、连接选择、连接路由选择。与I-NNI不同，它是在不同域间交换路由可达性信息，屏蔽了网络内部的拓扑信息。对多层拓扑结构间的E-NNI信息交互尤其是标准化的难点和重点。
ASON主要由三个国际化标准组织在推进，IETF,OIF和ITU-T。
(1)IETF
IETF的MPLS，到GMPLS是催生ASON产生的基础。ASON使用的信令协议CR-LDP，RSVP-TE都是IETF近来标准化的结果，而ASON的路由协议包括OSPF-TE，BGP，它们都在原先协议的基础上，对光网络发展的需求做了相应的扩展。最新增加的LMP链路管理协议也在不断修订中。
(2)OIF
OIF对ASON最值得肯定的工作是UNI1.0。由于有了UNI1.0，数据设备厂商和电信设备厂商在设备自动化互联时有了充分可信赖的依据。现在有了UNI1.0的第二版，还有正在标准化中的，引入了以太网业务，支持带宽动态改变的UNI2.0。0IF另一个重点研究的领域是E-NNI，力图在设备域间互联上提供互联互通的可能。
(3)ITU-T
ITU-T的优势是在协议框架搭建，网络管理和业务提供方面，依照ITU-T的建议，ASON只支持层叠模型，定义了G.8080/Y.ASON结构，区分了呼叫和连接，用抽象模型抽象化了信令协议，提出了路由协议的需求，支持DCN细化为SCN(信令连接网SignalingConnectionNetwork)和MCN(网管连接网ManagementConnection Network)仔细考虑了ASON网管的问题。
3.ASON技术优势
与现有的SDH组网技术相比，ASON有以下优点：
(1)统一的分布式控制/管理层面，与底层的物理实现技术无关，理论上讲支持各种带宽粒度的交换和管理，无论是IP路由器，ATM交换机还是光交叉连接设备都可以应用;
(2)快速的定制支持不同SLA(ServiceLevelAgreement)级别电路，不仅缩短了业务提供时间，提高了网络资源的利用率，还可提供新的带宽业务，如BODS(按需带宽服务)，OVPN(光虚拟专用网)等;
(3)支持端到端的连接建立、监控、保护和恢复，对各种网络拓扑结构，包括网状网的支持，增强了网络的流量工程能力。
三、ASON市场未来预测
在ASON出现之前，DWDM技术以满足Gilder定律的方式，每六个月翻一番的增长趋势极大地改善了骨干网长途链路上容量短缺的问题，不需要铺设新光纤，只需要增加波长路数，
运营商就可以充分满足巨量带宽的需求，带宽的极大丰富并不意味着运营商可以迅速满足用户对带宽需求的响应，在网络流量日趋数据化，突发性更大的背景下，对多粒度，动态带宽改变，迅速部署电路的强烈需求使得ASON日益重要和普及。当前市场上已经有Ciena、华为、中兴、朗讯、阿尔卡特等众多厂商宣称支持ASON的设备可供选择。在可预见的未来，ASON在以下四个方面将有极大的市场需求。
1.城域传送网的换代升级ASON+MSTP
在业务模式更加数据的今天，传统的SDH根本无法适应数据业务的需求，而基于SDH发展起来的MSTP(多业务传送平台)正在成为新一代城域网建设的首先技术。因为发展业务的需要，ASON与MSTP结合，由MSTP提供下层的物理传送通道，由ASON完成网络智能的控制和管理是未来必然的选择。
2.长途传送网的灵活波长业务
在长途骨干传输网上，配置灵活的波长上下路(如通过可重构光上下路复用器(R-OADM)，波长扩容或者长途干线链路保护/恢复，可以由ASON的分布式智能控制来提供，加上提供超长距离传输的ULH技术，长途大容量的实时电路指配、调度和保护可以在几分钟之内完成，极大地削减人工配置电路的复杂性、易错性和不灵活性。
3.对城域接入的支持如3G基站、企业网边缘路由器、网关、IAD等 新一代的MSTP除了原来的SDH接口，增加了对以太、MPLS甚至RPR(弹性分组环)接入的支持，考虑到未来无线3G应用的宽带需求，例如3G基站之间的互联，企业网络设备的速率升级，利用ASON为用户提供安全高速的二层VPN或者一层VPN满足互联需求是未来可预见的有吸引力的新业务。
4.对NGN的支持
NGN是下一代的未来通信网络，是基于分组的，基于控制与呼叫分离的，呼叫与承载分离的软交换、业务驱动型的，开放型的网络架构体系。ASON从本质上讲，它在业务传送环境里采用的交换技术不是分组，而是电路型的，但是它本身是和设备的物理传输/交换技术独立的，而且满足两个分离的特性，对将来的业务是开放的。ASON必然要符合NGN的框架约定，而且应是满足这个约定的重要的示范网络。
四、ASON局限性
迄今为止，还没有任何一项技术可称为完美无缺的，正在发展中的ASON也是一样。ASON的缺陷主要存在于：
1.标准有待完善
ASON的标准到目前为止有很大的进展，但是在互联互通，网络管理和管理平面本身的健壮性等方面还有许多工作要做。而且由于是多个标准化组织在参与，标准的沟通工作也比较麻烦。
2.测试设备不成熟
设备的成熟首先要依赖测试设备的成熟，当前号称推出GMPLS/ASON协议测试的公司，实际上都还没有成熟定型的产品推出，受标准不断更新的影响，也很难在当前拿出实际的产品。
3.流量工程、保护/恢复等特色功能的有效性
运营商在运行网络时，对实时监控能力、优化网络，提高网络的生存性永远是不断的追求，ASON号称可以解决这些问题，可是其真实有效性还没有经过真正的大规模网络现场测试，究竟是彻底解决问题还是仅仅减轻问题还没有也暂时不可能定论。
4.新业务的支持
ASON支持的业务种类很多，如SDH、OTN、以太网、存储网等，它对新业务也具有扩展性，其实ASON主要就是推销可快速部署的带宽，无论是波长出租，波长拨号，OVPN等都是如此。ASON宣称支持可保证QoS或者SLA的业务连接，包括点到点单向/双向连接，点到多点的单向连接。但是对后者，象在IP网中一样的多播机制(Multicast)还没有明确定义出来并加以验证，因此对某些应用，如观众所在地域分散的视频广播还没有特别高效的节省带宽的办法。
5.综合网管
ASON提供了新的网络控制管理平台，当然满足TMN的框架，但并不是排斥或完全代替已有的传输网网管系统，或者ATM网管，在涉及到底层的管理时还要与现有管理系统的相互配合，集成，在实际运营时，会产生比较繁琐的问题。
（英文版见下页）
About ASON Automatic Switched Optical Network
Frist,Preface
The development of modern optical communication networks counting from the PDH, through SDH / SONET / OTN to ASON now automatically switched optical network is the third generation, which fully reflects the optical communication network links from low to high speed, ultra-high speed, from the point point topology to the ring, MESH, from the low-speed electric power used in most high-speed multiplexing, optical multiplexing, from the main for the link, network element management to-end service management for the evolution of trends.
Today, support for ASON has become the optical equipment manufacturer promotion of their optical equipment necessary conditions, especially in China, with AT & T using Ciena introduced intelligent optical equipment, AlCAtel in Beijing, Lucent in Jiangsu deployment of intelligent optical networking products, domestic operators generally showed a warm welcome to the ASON, ASON is so important, operators and manufacturers to obtain unanimous praise, primarily because of:
(1) network transmission level technology has matured, including Virtual Concatenation, GFP (GenericFramingProcedure common frame of order), LCAS (LinkCapacity Adjustment Scheme link capacity adjustment scheme) and other new technologies and RPR (Resilient Packet Ring Resilient Packet Ring), MSPP / MSTP (Multi Service Provisioning Platform / Transport Platform Multi-service configuration / delivery platform) and other new platforms for voice / data network convergence to provide a variety of options;
(2) Regardless of the product or platform, network operators reduce operating, maintenance complexity, reduce network failure rate and improve the effective utilization of resources and faster than your opponents launched a new, flexible bandwidth service has been the most desired ;
(3) ASON for a variety of network equipment provides a unified control and management platform for the manufacturers to provide a technically led a powerful tool for intelligent optical networks, taking full account of how to meet the needs of operators.
Second, ASON technology features and protocol standards
1.ASON components and services
ASON mainly by the following three separate planes, namely, the transport plane, control plane and management plane. (There is also a rarely mentioned in the DCN surface to carry
control signals). Similar to the ATM, ASON supports three connections, namely, a permanent connection PC (PermanentConnection), switched connection SC (SwithchedConnection) and soft permanent connection SPC (SoftPermanent Connection). Permanent connection is also known as custom connected by network management system or by hand to complete, and switched connection is a connection-driven signaling, end-users as needed, can be established between any two terminals connected. SPC and PC connections are initiated by the management plane connection, the difference is within the network is to use optical signaling, or by network management interface. Optical network signaling to establish a connection for internal use when it comes to the control plane signaling part of the controlling entity of each network element requires dynamic interaction between the signaling information, the other part of the routing control plane also in the entities exchange routing information. (Naming and Addressing) Construction chain requires signaling network naming and addressing (Naming and Addressing) policy support.
2.ASON interface definition and network protocol suite
As the network architecture is AS0N Overlay Model (OverlayModel), ASON network logically divided into UNI (UserNetworkInterface user network interface), I-NNI (Inter-Network Network Interface internal network - network interface) and E-NNI (Exterior-Network Network Interface external network - network interface) in three parts.
UNI main client running on the optical network and optical network equipment, and is the business of the requester and service provider control plane entities of the two-way signaling interface, the main function is to establish a connection between the two, the connection removal, connection changes, state query, do not exchange routing information between each other, optional features are neighbor discovery, service discovery. UNI1.O version mainly for SDH interface in the next version of UNI2.O will add support for Ethernet. UNI2.0UNI2.0 signaling information on the integrity, security and so on greater than 1.0 have concerns. Currently there are three candidates UNI protocol: PNNI (private network - network interface PrivateNNI), CR-LDP (constraint-based routing label distribution protocol ConstrainedRouting-LabelDistribution Protocol) and RSVP-TE (resource reservation protocol with flow expansion Resource Reservation Protocol - Traffic Extension).
Since the domain is running, usually with a device's device, there is no recommended standard, each device manufacturers can use the proprietary interface protocol can also use the well-known interface protocol. I-NNI interface using protocols including routing protocols and signaling protocols, routing protocols can be OSPF-TE (Open Shortest Path First Protocol - with traffic engineering extensions OpenShortestPathFirst-Traffic Engineering), IS-IS-TE (Intermediate System - Intermediate System Routing Protocol - with Traffic Engineering extensions Intermediate System-Intermediate System-Traffic Engineering) or BGP (Border Gateway Protocol Border Gateway Protoco1) protocol, signaling protocol is mainly CR-LDP and RSVP-TE.
E-NNI inter-domain control plane are different entities of the two-way control interface to support call control, resource discovery, connection control, connection options, connection routing. And I-NNI different, it is between the different domains exchange routing reachability information, shielding the internal network topology information. Multi-layer topology of the E-NNI between information exchange, especially the standardization of difficulty and focus.
ASON mainly by the three international standards organizations in promoting, IETF, OIF and
ITU-T.
(1) IETF
ASON signaling protocols used in CR-LDP, RSVP-TE is the result of IETF has recently standardized, and ASON routing protocols including OSPF-TE, BGP, they are in the original agreement, based on the needs of the development of optical network do be extended. The latest addition to the LMP Link Management Protocol are also constantly revision.
(2)OIF
Thanks UNI1.0, data equipment manufacturers and telecommunications equipment manufacturers in the interconnection of automation equipment have a full time basis trusted. Now, with UNI1.0 the second edition, there is standardization, the introduction of Ethernet services to support dynamic bandwidth change UNI2.0. 0IF Another key research area is the E-NNI, in a bid field equipment provide interoperability between the Internet possible.
(3)ITU-T
ITU-T the advantage of the framework agreement to build, provision of network management and operations, in accordance with ITU-T recommendations, ASON only supports cascading model, defined G.8080/Y.ASON structure, a distinction between call and connection, with the abstract abstract model of a signaling protocol, proposed routing protocol needs to support DCN subdivided into SCN (Signaling Connection Network SignalingConnectionNetwork) and MCN (network connectivity network ManagementConnection Network) careful consideration of the ASON network management issues.
3.ASON technical advantages
And compared with the existing SDH network technology, ASON has the following advantages:
(1) a unified distributed control / management level, and the underlying physical implementation technology has nothing to do, in theory, support a variety of exchange and management of the bandwidth granularity, whether IP routers, ATM switches or optical cross-connect devices can be applied;
(2) rapid customization support different SLA (ServiceLevelAgreement)-level circuit, not only shortened the time for service provision and improve network efficiency, bandwidth can provide new services, such as BODS (on-demand bandwidth services), OVPN (light Virtual Private Network), etc.;
(3) to support end to end connection establishment, monitoring, protection and recovery, on a variety of network topologies, including mesh networks to support and enhance the network's traffic engineering capabilities.
Third, ASON forecast the future market
Before the appearance of the ASON, DWDM technology to meet the way Gilder's law, doubling every six months, the growth trend has greatly improved the long-distance backbone network link capacity shortage problem, do not need to lay new fiber, only the large ones need to increase the wavelength , operators can fully meet the massive demand for bandwidth, the bandwidth of the great wealth does not mean operators can quickly meet customer demand for bandwidth in response to growing data traffic in the network of, a larger context of sudden,
multi-size, dynamic bandwidth changes, the strong demand for the rapid deployment of the circuit makes the ASON increasingly important and popular. The current market has Ciena, Huawei, ZTE, Lucent, Alcatel and other vendors claim to support ASON devices to choose from. In the foreseeable future, ASON in the following four areas will have great market demand.
1. The new generation metro transport network upgrade ASON + MSTP
More data in the business model today, the traditional SDH data services simply can not adapt to the needs of developed SDH-based MSTP (Multi-Service Transport Platform) is the first of a new generation of MAN technologies. Because the development of business needs, ASON and MSTP combination provided by the MSTP lower physical transmission channel, completed by the ASON network intelligent control and management of the inevitable choice for the future.
2. Long-distance transmission network service flexible wavelength In the long-distance backbone transmission line, flexible configuration, the wavelength of the upper and lower road (such as up and down through the reconfigurable optical multiplexers (R-OADM), wavelength expansion or long haul link protection / restoration, can be distributed intelligent control to ASON offer to provide ultra-long haul transmission with ULH technology, real-time long-distance high-capacity circuit assignment, scheduling, and protection can be completed in minutes, greatly reducing the complexity of manual configuration circuit, error-prone and non-flexibility .
3. To the metro access and flexible support, such as 3G base stations, enterprise edge routers, gateways, IAD, etc.
A new generation MSTP SDH interfaces in addition to the original, adds Ethernet, MPLS or RPR (RPR) access to support, taking into account the future demand for wireless 3G broadband applications, such as the interconnection between the 3G base stations, enterprise network equipment the rate of escalation, the use of ASON to provide security for the user, or a layer of high-speed Layer VPN Internet VPN to meet foreseeable future demand for attractive new business.
4. For the support of NGN
NGN is next generation communications network is packet-based, based on the separation of control and call, call and bearer separation of the soft-switching, business-driven, open network architecture system. ASON In essence, it is transmitted in the business environment is not used in packet switching technology, but the circuit type, and equipment, but it itself is the physical transmission / switching technology independent, but also to meet two separate properties, the future The business is open. ASON is bound to comply with the agreed framework of NGN, and should be agreed to meet this important demonstration network.
Fourth, ASON limitations
ASON defects mainly in:
1. The standard to be improved
ASON standards has seen much progress so far, but in the interconnection, network management and robust management plane itself, there is still much work to do so. And because it is involved in several standardization organizations, the standard of communication is also more trouble.
2. Test Equipment immature
Equipment, test equipment, mature first mature to rely on the current known release GMPLS / ASON protocol testing company, in fact, stereotypes are still not mature product launch, the impact of constantly updated by the standard, it is difficult to come up with actual product in the current .
3. Traffic engineering, protection / restoration of features such as the effectiveness of
Operators to run the network, real-time monitoring capability, optimize network, increase the survivability of the network is always constant pursuit, ASON known to solve these problems, but its effectiveness has not real large-scale network of genuine field test, whether is completely solve the problem or just temporarily alleviate the problem are not yet conclusive.
4. The support of new business
ASON supports many different types of business, such as SDH, OTN, Ethernet, storage, networks, etc., it also has a new business expansion, in fact, ASON is mainly selling to the rapid deployment of bandwidth, whether it is leased wavelengths, the wavelength dial, OVPN etc. This is true. ASON claims to support guaranteed QoS or SLA's business connections, including point to point one way / two-way connection, one-way multipoint connection. But the latter, as in the same IP network multicast mechanisms (Multicast) has not clearly defined and verified it, so for some applications, such as where geographically dispersed audience video broadcasting has not particularly efficient way to save bandwidth .
5. Integrated Network Management
ASON control provides a new network management platform, of course, to meet the TMN framework, but not exclusive or completely replace the existing transmission network management system, or ATM network, in relation to the management of the bottom also with the existing management system of mutual cooperation, integration, when in actual operation, will have more complicated problems.