Low-Cost SDH Is an Inevitable Choice for Access Network Construction in the Near to Medium Term
Low-Cost SDH Is an Inevitable Choice for Access Network Construction in the Near to Medium Term
The current status of metropolitan optical networks is that SDH/MSTP (DWDM) optical networks have become the mainstream for metropolitan area network and aggregation layer optical transmission network construction. As a natural technical extension, adopting SDH/MSTP in the access network should be ideal, but in reality this is not the case. Due to increasingly fierce market competition, operators have become more rational in their investment decisions. At the access layer, given the large number of devices, equipment price becomes increasingly important. Although traditional PDH equipment is technologically outdated, it is still widely deployed due to its low cost, especially in the "last mile" access for key accounts of fixed-line operators. As a result, a certain barrier has formed between the aggregation network SDH/MSTP and the access network PDH, giving rise to many problems.
For example, the subsequent maintenance and management issues caused by the large number of PDH devices and various converters at the access layer; the problems caused by the large number of E1 lines used for "back-to-back" connections with the core network; difficulties in network maintainability and optimization; the challenge of meeting the high standards required by key accounts; and issues related to the sustainable development of the network (e.g., 3G access).
For key accounts, their requirements for the access network are: diverse service interfaces, high reliability, easy service expansion, high security, and most importantly — price! From the operator's perspective, meeting the service needs of key accounts is their primary goal, followed by reducing costs and improving competitiveness. The current main access methods — PDH, converters, and media converters — can only solve some of the above problems, but face significant difficulties in service expansion, reliability, and security. The existing key account access network structure is fragmented, with a wide variety of access methods, strong regional characteristics, numerous types of terminal equipment, many blind spots in network monitoring, poor network scalability, and a lack of flexible service access capability. Therefore, a new approach is urgently needed to meet the demands of network development, and MSTP can precisely satisfy these requirements.
Why MSTP? Since MSTP has already been adopted in the metropolitan core network and aggregation network, using this technology in the access network can achieve excellent network convergence and matching, enabling seamless connectivity and fully protecting the operator's existing investment. Adopting MSTP at the access layer can bring the enormous bandwidth advantages and technological advantages of the core network into the access network domain. Can the SDH/MSTP of the core layer and aggregation layer be directly transplanted to the access layer? This is very difficult. The main reason is that access layer equipment needs to be specifically designed for the access network — compact, easy to install, convenient to maintain, with better environmental adaptability, matching the access network topology, supporting IP services, and most critically, low cost. Therefore, low-cost MSTP equipment is the best answer to solving the key account access problem.
Two years ago, Huahuan Company proposed the slogan "Carry MSTP/SDH to the end!" and launched the Metro Direct Connect solution. By adopting Huahuan's Metro Direct Connect equipment, the original media converters and converters can be replaced, achieving full SDH or MSTP deployment in the access network, thereby realizing seamless connectivity across the entire network.
The Metro Direct Connect H9MO-LM series equipment includes: the flexible device H9MO-LMFIT, the aggregation device H9MO-LMX, and the terminal devices H9MO-LM, H9MO-LM/4E1, H9MO-LMV, H9MO-LME, H9MO-LMC, H9MO-LM63, etc. Its main features include: no need to modify the existing SDH transport network, protecting the operator's existing investment. By using STM-1 uplink optical ports at the aggregation side to replace the E1 "back-to-back" method for connecting to the metropolitan SDH/MSTP transport aggregation network, a large number of E1 interface boards, E1 cables, DDF distribution frames, and corresponding equipment room space and associated additional costs can be saved, while maintenance and network management become easier, significantly reducing overall costs. User extension adopts standard SDH optical interfaces, supporting various topologies, making network expansion convenient, and allowing various standards-compliant terminal devices to be easily connected, eliminating the concern of vendor lock-in for operators. Due to the end-to-end SDH standard, VC-12 can reach the network edge directly. In addition, the Metro Direct Connect solution specifically supports star network topology, as well as complex topologies such as ring, chain, and mesh networks, providing users with flexible networking options.
Compared with EPON and GPON technologies, which have not yet seen large-scale application experience, SDH is more promising in the access network. First, SDH has already been widely and successfully commercialized in the market; all that is needed is to introduce this technology from the core network and metropolitan area network into the access network and reduce costs. Second, TDM services currently remain the main source of operator profits, and EPON and GPON have relatively weaker support for TDM services, whereas SDH can support both TDM services and data services well. Therefore, for operators, considering the existing massive SDH resources, the reality that metropolitan network services are still predominantly TDM-based, and the fact that mature low-cost, low-price SDH equipment has already appeared on the market — which will bring numerous benefits to telecom operators in construction, operation, and maintenance — choosing low-cost SDH is an inevitable choice for access network construction in the near to medium term.