Due to the inadequacy of the early transmission system PDH, the representative products of SDH equipment, Metro1000, Metro3000, Metro5000, the birth of the fundamental to help customers solve the problem of access between users and the core network due to the limitations of the incoming media bandwidth can not keep up with the development of backbone network and user business needs, and at the same time to improve the transmission network of a large number of Bandwidth utilization on the transmission network. So far, it has been a mature and standard technology, and widely used in backbone network.

In the access network application can be SDH Metro1000, Metro3000, Metro5000, technology in the core network in the huge bandwidth advantages and technical advantages into the field of access network, make full use of SDH synchronous multiplexing, standardized optical interfaces, a strong network management capabilities, flexible network topology capabilities and high reliability to bring the benefits of the development of the access network construction and long-term benefit. The company has been able to benefit from the development of access network construction in the long run.

However, with the ever-increasing demand for IP data, voice, image and other services, the broadband technology of user access and premises network has been rapidly popularized, and the large-scale construction of transmission backbone network has been promoted. Due to the great changes in the service transmission environment, the original metropolitan area network (MAN), which mainly carries voice, has failed to meet the requirements of service transmission and convergence in terms of capacity and interface capability. Therefore, MSTP technology came into being.

MSTP representative products are OSN1500, OSN2500, OSN3500, is based on SDH multi-service transmission platform, in addition to SDH functions, but also has the Ethernet function and ATM function, can be realized at the same time TDM, ATM, Ethernet and other services, access, processing and transmission, to provide a unified network management of multi-service nodes. Along with the development of telecommunication network, MSTP technology is also progressing, which is mainly reflected in the processing of Ethernet services.

Ethernet pass-through function: It is to map the signal from Ethernet interface directly into the virtual container (VC) of SDH without going through Layer 2 switching, and then transmit it point-to-point through SDH equipment, which is the feature of the first-generation MSTP technology;

Ethernet Layer 2 switching function: refers to the realization of Ethernet link layer-based data frame switching between one or more subscriber Ethernet interfaces and one or more independent point-to-point links based on SDH virtual containers, and is a second-generation MSTP technology feature;

The third-generation MSTP OSN1500, OSN2500, OSN3500 introduces an intelligent adaptation layer (Layer 1.5) between the data service and the transmission virtual container, adopts the PPP/LAPS/GFP high-speed encapsulation protocol, supports the virtual cascade and the link capacity automatic adjustment (LCAS) mechanism, and therefore supports multipoint-to-multipoint connection, scalability, user isolation and bandwidth sharing, and supports Ethernet link-layer switching and bandwidth sharing. and bandwidth sharing, supports Ethernet QOS, SLA enhancement, blocking control, fair access, and provides service layer ring protection.

Using MSTP OSN1500, OSN2500, OSN3500, the equipment provides EOS access mode, the router or switch directly adopts the Ethernet interface. From the interface considerations, because the MSTP is also the use of ordinary RJ45 (10/100BaseT) interfaces to achieve interconnection, greatly saving the cost of POS optical interface interconnection, and can be achieved through the unified network management of MSTP end-to-end business management. In the EOS (Ethernet Over SDH) technology as the characteristics of the MSTP equipment out of the previous, SDH technology to carry data services network is usually through the POS (Packet Over SDH) will be mapped to the SDH packet virtual container VC within the way, the way is actually in the use of transmission equipment based on a point-to-point " This method is actually using a point-to-point "leased line" based on transmission equipment, which requires a pre-determined bandwidth, and most of the traffic enters the network in the form of dedicated "pipes" with the granularity of E1, E3, STM-1, STM-4.

Article source: http://www.opticaltrans.com