| With rapid development of network technology, rapid growth of user demands and constant emergence of new network services, application scenarios of various services have become increasingly complicated. The IP-based network will gradually bring about the change of future network in control and services, promoting the original vertical network characterized by stratification between technology and business to evolve into horizontal network. In addition to comprehensive consideration of social development and users’ demands, HD video and other broadband multimedia services and the proposed 5G network poses higher requirements for the rate, bandwidth and coverage of access network.Moreover, for different kinds of user, there exist great differences in the demands for network traffic and use time; so the convergence layer and access layer for network are required to have the function of flexibly allocating network resources. Therefore, the current metro network and access network mainly face the following two challenges:(1) With the continuously increasing demands of users for HD video,online games and other services and constant expansion of application scenarios, the main goal of current access network development is to improve network capacity, to increase network bandwidth and to expand network coverage.(2) In addition to large capacity and wide coverage, access network is characterized by strong suddenness in traffic flow; that is, the traffic varies greatly with fluctuation in time and region; the increase of network rate will lead to rapid increase in variation range of traffic. Moreover,there exists great variation in the traffic of different users; so the access network is required to flexibly allocate bandwidth resources and support different grades of service packages and other control demands. Through flexible and unified management system, the access network provides better quality services as well as more secure and reliable network for users. According to the above development needs, the research work in this paper was conducted from the following aspects:(1) On the basis of the analysis of research status and development trend of access network, the structure of SDN-based annular convergence access network consisting of central station, remote node, optical network unit, metro convergence DWDW fiber ring and TWDM/TDM access fiber tree was studied. Hence, the convergence network and access network could be combined with SDN to meet the development demands of access network for programmability, larger capacity, higher bandwidth,wider coverage and high efficiency in resource scheduling and allocation.(2) The unified management and control system for the SDN-based metro-access network was studied. The management and control of the whole network is a necessary link in the process of network development.Based on the SDN-based separation of data layer from control layer, the architecture for stratified control system consisting of Web network management layer, controller layer and Agent layer was built, which could realize such functions as shielding the differences between the underlying devices, automatically discovering network topology, flexibly configuring the devices and controlling the multi-domain devices in a unified way. In addition, it also implemented the unified management of the optical network unit, optical line terminal, switches, OXC and other devices in the metro-access network. This management system can support the login in the multi-virtual business mode, enabling the operation of network virtualization of multiple mutually-independent virtual networks on the same underlying physical network.In this paper, the corresponding functional tests on the unified management and control system and the relevant analysis of application scenarios were conducted finally, meeting the desired goals. |
