About SDH

The MUX series products are designed in accordance with the latest recommendations of the International Telecommunication Union (ITU-T) and comply with the telecom equipment network access specifications of the Ministry of Information Industry. The equipment features comprehensive functions, reliable operation, flexible configuration, rich tributary interfaces, and powerful network management capabilities, supporting various network topologies and providing multiple protection functions.

    Metropolitan transmission networks generally adopt a three-tier structure consisting of the backbone layer, aggregation layer, and access layer. With the development of SDH technology, the aggregation layer of large metropolitan area networks and the backbone/aggregation layer of small and medium-sized metropolitan area networks mostly adopt SDH/MSTP ring network configurations. As a natural technological extension, the use of SDH/MSTP equipment in the metropolitan access layer should be an ideal choice. However, due to the small traffic volume and large number of access layer nodes, which are highly price-sensitive, except for scenarios with high network security requirements where small-capacity SDH ring networks are deployed, most urban access layer networks still rely on star-connected PDH optical terminals. Major telecom customers are also mostly connected via PDH. To gain first-mover access to major customers, a large number of PDH devices are deployed in a point-to-point topology at the edge of metropolitan transmission networks. This access method has brought a series of serious problems to the later maintenance and sustainable development of the entire network.

    First, ordinary PDH optical terminals have limited networking capabilities, with most only capable of forming simple point-to-point networks. This results in a large stack of PDH optical terminals, interface converters, or media converters at the central office. This complicates network operation and maintenance and is not conducive to operators' network structure optimization and service integration.

    Second, since PDH optical interfaces lack a unified rate standard, at most convergence points between the aggregation layer and access layer, the access layer PDH optical terminals and the aggregation layer SDH/MSTP network can only be connected "back-to-back" through physical interfaces such as E1. This requires extensive cabling and DDF distribution frames, which not only increases the corresponding equipment room area and considerable accessory costs, but also, because E1 circuit adjustments mostly rely on manual methods, greatly increases the probability of electrical interface contact issues, significantly reducing the overall system reliability and ultimately lowering operator revenue.

    Third, the use of [PDH](

    In view of the above reasons, many telecom operators have begun to restrict the large-scale use of PDH systems in telecom networks, and some operators' PDH systems have already been decommissioned. Telecom operators are seeking new technical means or solutions that not only retain the low cost, speed, and efficiency advantages of the original approach but also overcome the disadvantages of non-standardized interfaces, difficult maintenance, and low service quality.

    The penetration and integration of MUX technology into the network edge will become a development trend in the fiber access market, which is also the concept and goal that Raytrans Digital has consistently upheld. Leveraging technological breakthroughs in the field of SDH core chips, Beijing Raytrans Digital Technology Co., Ltd. has officially launched a low-cost SDH metropolitan access network solution. The main concept and approach of this brand-new solution is to truly push SDH technology to the network edge, enabling VC-12 to reach the network end directly, allowing end customers to enjoy the benefits brought by SDH/MSTP technology itself, and ensuring that all user services flow smoothly throughout the entire SDH network. The most critical point is that its price is comparable to PDH equipment, making it possible for telecom operators to deploy SDH technology on a large scale in metropolitan access networks.