Optical Transport Network (OTN) based on wavelength division multiplexing technology is the next-generation key transmission network. The technology matures and the application of IP traffic transmitted on the network and other based on the explosive growth of data services in packet transmission, transmission capacity requirements continue to increase rapidly, Dense Wavelength Division Multiplexing (DWDM) technology and optical amplifiers (OA) transmission network to the optical transport network based on optical networking technology. Based on the OTN transport network will allow people to expect intelligent optical network gradually become a reality for network operators and customers to provide safe and reliable, effective price, the customer has nothing to do, manageable, maneuverable and efficient next-generation optical transport platform.
The optical transport network for IP services, has become an important issue in the next step in the development of optical communication adapter transmission demand for IP services. The optical transport network from a variety of angles and multiple solutions compatible with existing technology, due to the large number of applications of the SDH equipment, in order to solve the processing and transmission of data services, based on SDH technology research and development MSTP equipment in the network, and has a large number of applications compatible with the existing technology, but also to meet the data transfer function of the business. But with the increase of data traffic particles and more detailed requirements for processing power, the business on the transport network, the demand for both: the one hand, the transmission network to provide a large pipeline, then the generalized OTN technology (in the electric field is OTH, in the optical domain ROADM) provides a new solution, it solves the SDH-based VC-12/VC4 the cross particles too small, the scheduling is more complex and does not meet the needs of large particles service delivery, in part, to overcome the WDM positioning difficulties of system failure, the main point to point connection, networking, network capacity is weak, and can provide network survivability means and weak shortcomings; the other hand, the business of light transmission network more detailed processing requirements, the industry solution for packet transport network, and is currently involved in major technologies, including the T-MPLS and PBB-TE.
With the network business is a growing demand for bandwidth, operators and system manufacturers have been constantly consider the problem of improving the transmission technology of the business.
The evolution of the digital transmission network from the initial first generation of digital transmission network based on T1/E1, has experienced the development of the currently third-generation digital transmission network in OTN-based second-generation SONET / SDH-based digital transmission network. The first and second transmission network initially to support voice services specifically designed to also be used to transmit data and images business, but the transmission efficiency is not high. In contrast, the third-generation transport network technology, designed to support voice, data and image services, with the other protocols can support the bandwidth allocated on demand (BOD), can be cut and the quality of service (QoS) and Optical Virtual Private function of the network (OVPN).
In 1998, the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) formally proposed the concept of the OTN. From the functional point of view, the OTN in the subnet can be transmitted in the form of all-optical, optical – electrical – optical conversion in the subnet boundary. In this way, each subnet can 3R regenerator join, so as to constitute a large optical network shown in Figure 1. Therefore, OTN can be seen as a transitional application of the evolutionary process of the transmission network to all-optical networks.