Ethernet Protection Technology Knowledge

With the acceleration of service IP-based transformation, the service types carried by telecom networks have undergone fundamental changes, shifting from time-division multiplexing (TDM) traffic dominance to a packet-dominant traffic pattern. The change in service types has imposed new requirements on the bearer network. The existing SDH/SONET-based transport network is suitable for carrying synchronous circuit services with constant rates, but it has certain limitations in carrying packet services with bursty and unpredictable characteristics, especially large-granularity data services (GE or 10GE). Therefore, how to select appropriate packet-bearing Ethernet technologies to adapt to the IP-based network traffic trend and provide data services with the same available, effective, and manageable services as traditional circuit services is a major challenge for operators in network construction.
**[Ethernet Ring Network Protection Technology](
Currently, when various Ethernet technologies are used for network construction, many manufacturers' devices mostly support ring networking, and the various technologies are largely similar. Physically, they all adopt a ring network topology, while logically they are chain or tree topologies; the number of nodes on the ring is related to device performance, service traffic, and transmission distance, with no theoretical limit. Most existing ring network technology solutions are based on the ITU-T G.8032 standard and extended from RPR or ERP technologies, such as MSR, ZESR, and E-spring. The main differences lie in the flexible selection of different fault detection and congestion points, which can improve fault detection time and network bandwidth utilization.
Ethernet technology, due to its inherent simplicity, efficiency, and low cost, is rapidly evolving from a primary LAN networking technology to MAN and WAN networking technology. However, the difficulty in providing fast service protection and fault recovery mechanisms is one of the main reasons hindering its large-scale deployment in MANs. Therefore, Ethernet ring network protection technology in SDH will become a key research focus for major communication equipment manufacturers.
**Traditional [Ethernet Ring Network Protection](
From a traditional perspective, automatic protection switching based on SDH ring networks typically refers to E1 line protection, with two ring protection modes: two-fiber unidirectional channel protection ring and two-fiber bidirectional multiplex section protection ring. Currently, the first mode is more commonly used, with one working ring and one protection ring, where the service flow directions of the two rings are opposite, and ring protection is achieved through the "concurrent transmission and selective reception" function of the network element tributary board. For STM-1 optical interfaces, the entire network optical line provides a total transmission bandwidth of 63 E1 channels. Generally, the mentioned Ethernet ring protection is also based on E1 interface protection. In this case, when the number of sites on the SDH ring increases, the available Ethernet resources are fewer, and the Ethernet bandwidth is smaller.