Building a flexible and efficient broadband metropolitan Area transport network

The rapid rise of video services, represented by Peer-to-peer and IPTV, has greatly stimulated the bandwidth requirements of metropolitan transport networks. According to OVUMRHK company forecasts, the next five years the DSL and FTTx market growth rate of 18% and 33% respectively, metropolitan traffic will grow about 30 times times, the broadband trend is magnificent. To this end, how to deal with the metropolitan transport network? The transmission of mass IP service in the metropolitan Area Transmission network under the broadband power flow has become the main problem to be solved urgently in the metropolitan Area transport network. The traditional metropolitan transport network is a network with SDH as the base, and a special line for voice and small particles, which is called narrowband transmission network. With the development of broadband service, the requirement of broadband for metropolitan transport network must be transformed into a broadband transmission network, which can carry IPTV and all kinds of large granular line business. WDM Indispensable home broadband penetration in South Korea is 93%, the average broadband rate of 49.5Mbps, Japan's home broadband penetration rate of 55%, the average broadband speed of 63.6Mbps, the United States broadband penetration of 57%, the average broadband rate of 4.9Mbps ... The global broadband market is booming, according to the Global Broadband Network construction report released by the International Foundation for Information Technology and innovation (ITIF) in May 2008. With the rapid development of broadband video service, more and more urgent demands are put forward on the bandwidth of transmission network. At present, the family broadband is from 2M access to 30M or even 100M forward, the evolution of UWB is the trend. Assuming that the bandwidth of each home broadband access is 30M, in order to develop 500,000 broadband users for example, the metropolitan core will converge to 40 10G wavelength, if the 100M plan, the Metro core will appear more than 120 10G wavelength. In the face of the rapid development of broadband access, WDM technology can make full use of the vast bandwidth of optical fiber resources, transmission characteristics of a completely different signals, transparent transmission, carrying a variety of formats of "business" signal, expansion convenience, save costs. With these advantages, WDM becomes an indispensable part of metropolitan area network. In order to meet the bandwidth demand of broadband service, the city core layer of medium and small cities needs to be planned according to 40 10G wavelength; large cities need to be programmed by 80 or even 160-wave 10G wavelength, and when necessary, 40G technology should be introduced to avoid running out of wavelength. OTN: Networked WDM traditional metropolitan area network can be used to dispatch and protect the traffic between metropolitan sites through SDH, but SDH is not suitable for broadband service in bandwidth and transmission efficiency. However, the dispatch and protection requirements between metropolitan sites still exist, and OTN precisely meets the requirements of scheduling and protection of large granular business. Traditional WDM is a point-to-point application, it lacks the technology of expanding capacity and distance, end-to-end business scheduling and protection, and otn can overcome the weakness of WDM. Otn is able to transfer point-to-point WDM links into a highly efficient transmission network with end-to-end scheduling and protection mechanisms, so we interpret OTN as networked WDM. If WDM is likened to a highway that delivers broadband services, then OTN is the link letter.Expressway overpass, with the junction of the overpass, to form an efficient operation of the information superhighway system, to do both wide its way, and smooth its flow. "WDM introduced OTN can be divided into two stages-the first phase is to introduce the Otn interface in the WDM system, including the line interface and the branch interface (also known as Inter-domain interconnect interface or business interface)." The Otn interface is introduced into WDM system, which can realize the end-to-end performance and fault monitoring of wavelength channel. Otn can realize the transparent transmission to a variety of customer signals, which is a prerequisite for routers to adopt 10GE interface. The second stage is the introduction of T-bit large capacity crossover equipment based on OTN, so as to improve the reliability of the transmission network, realize the fast operation and dispatch of the large wavelength channel, and optimize the structure of IP network. "said Zhang Chengliang, deputy chief engineer of China Telecom's Beijing Research Institute. It is worth mentioning that Otn becomes the only means to manage the resources of optical domain and domain system. The development of broadband allows a large number of wavelengths into the metropolitan area network, large particles of GE, 10GE become the mainstream network interface, whether WDM or in recent years has become a hot roadm, can not solve the "multi-granular, multi-layer network" complex operation, management and maintenance problems, but OTN can achieve the light layer and electric layer business unified management. Otn is getting better as Ctomickreeve, a former BT company, said: "Due to the limitations of SDH and traditional WDM, OTN will become more and more popular with operators." At present, the global mainstream operators are very concerned about the development and application of OTN technology, most operators of WDM transport interface has been implemented OTN function, OTN has become the backbone of transport networks and core transport layer of the mainstream support technology. Three stages of development as early as 2006, OVUMRHK company accurately predicted the market development of OTN, "the otn ability of equipment occupies the global optical network market 11 billion U.S. dollars 3 billion, the next 5 years this growth opportunity will gradually expand." In the process of transferring network operators to the packet based optical transfer network, OTN provides more efficiency and lower cost. Otn will step over the SONET, effectively manage and deliver large granular high-bandwidth services. Experts pointed out that the OTN market development experience the following three stages. The first stage is the interface of the Otn, known as Preotn, this phase of the different manufacturers of equipment will support the standard G.709OTN definition of encapsulation, mapping, overhead management and forward error correction. This phase began in 2005 and is now largely completed. The second stage is the ability to cross connect. This phase began in 2006 and is now in a state of steady progress. At the end of 2006, Huawei unveiled a new generation of intelligent optical transmission system osn6800/3800 at the ITU Hong Kong exhibition, the industry's first OTN device based on WDM platforms. By the end of May 2008, more than 5000 sets of OTN equipment have been operating stably in the global operators ' network, including China Mobile, China Telecom, Vodafone, Telefonica and other well-known operators, OTN technology maturity and reliability has withstood the test. The third stage is to support the Ason/gmpls control plane, with intelligent optical networking capabilities. Since 2006, some technology-leading equipment suppliers have proposed that Otn be able to have ASON/GMPLS capability, and there is already intelligent Otn network into operation. Carrying broadband, bearing the future now, after OTN finish the optical layer intelligence, and support the light layer, electric layer intelligent control of the ASON/GMPLS equipment has been available. The Ason of WDM is a new stage of technology development in Ason, with higher service carrying efficiency, more robust, more reliable network, complete automation and intelligent network bringing significant capex and opex savings. Most experts in the industry believe that the future of the metropolitan Core transport network will be the IP and Otn composed of two-tier network, GMPLS will become the data equipment and optical transport equipment, unified control plane. At the high-end exhibition of the transport network held in Beijing in May 2008, Huawei demonstrated a OTN system with T-bit crossover capability that supports full ODU1/OUD2/ODU3 crossover and supports wavelength, du unified gmpls control. According to OVUMRHK company statistics, Huawei's Metropolitan wavelength Division equipment in the fourth quarter of 2007, the first quarter of 2008, the market share of the world's first. The rapid development of OTN provides a strong guarantee for the operators to expand their future business. Taking a well-known European fixed-line operator as an example, the operator has been building a new generation of WDM networks since 2007 to speed up the development of broadband services, with the goal of simultaneously satisfying the network's flexibility and reliability requirements for both broadband carriers and a wide range of dedicated lines, including GE, 10GE and wavelength. Using the features of Otn openness and end-to-end connectivity, the operator deploys an integrated WDM/OTN network that extends from the national trunk to the metropolitan core and the metropolitan edge access. Through OTN powerful OAM capability, the unified management of ROADM system and large granular electric layer business is realized, and the business opening time is shortened from the traditional wave minutes to several minutes. The initial target of the carrier's flexible WDM network has been realized, and the next step is to improve the utilization of network resources and the efficiency of business protection. ASON/GMPLS network based on Otn has become a new planning focus, now network equipment only through software upgrades can obtain ASON/GMPLS ability, rapid expansion of high-bandwidth business, to win the future opportunity.