The development history of the old fashion three generation optical fiber access equipment

Because of the increasing demand for different kinds of information, the accompanying IP data, voice, and Multimedia, image and other new business needs have led to the development of the network environment of major network operators.
The change of the ground. In the past, the traditional metropolitan area networks and access networks, which are mainly designed to simulate voice, are on the capacity and interface types.
It has been unable to meet the requirements of various new business transmission and processing. So forced by the sudden surge of social information.
Vigorously, technologies and devices that provide new services for metropolitan area networks and access networks have developed rapidly.
Among them, the development of MSTP (multi service transmission platform) and PON (passive optical network) is the most representative.
It is the best solution based on optical fiber transmission technology and providing various new services on metropolitan area network or access network.
Optical fiber access technology based on optical cable is the development direction of broadband network in the future, and its development is inseparable from optical fiber.
The development and support of access devices is just like fish and water. Talking about optical fiber access equipment has to mention its three generation.
Experience:
The first generation uses PDH (fiber optic terminal) equipment, including point-to-point and Star office devices.
It has the function of converging. All of them adopt PDH transmission protocol and no optical interface specification. User services such as E1 and number
The service is multiplexed by private PDH protocol through the remote device and transmitted to the local device through optical fiber. Local end
The device divides the PDH optical signal according to the private protocol and converts it to E1 PDH interface.
The cable is connected to the Metro backbone / sink device through the DDF distribution frame. Due to the limitation of PDH protocol, all kinds of optical fibers are produced.
The access device is out of date soon.
In the second generation, in view of the defects of the first generation of equipment, some PDH equipment manufacturers developed second generation of equipment, that is, in the Bureau.
A SDH (dense wavelength division multiplexing) terminal card is added to the terminal device. It is still used between local and remote devices.
The private PDH protocol provides a converging function at the local terminal, which reuses the original E1 signal through the SDH terminal card.
The standard SDH interface is also given. It mainly solves the problem of interconnection between local device and Metro backbone equipment and unified interface.
Standard.
The third generation is SDH direct access equipment, including converging and non converging. As the new business covers a wide range of new businesses
The generation SDH direct access device has been able to transmit automatically to SDH according to the SDH specification; non convergent type.
The remote device can be directly connected to the metropolitan area network convergence node through the SDH optical interface, which is suitable for the convergence layer network.
The upper branch has fewer business interfaces. The converging type inserts the SDH converging device at the local end, which will come from multiple directions.
VC12 services converge to the uplink SDH interface, thereby saving the STM-1 interface on large capacity backbone node devices.
Number of cards. It mainly solves the compatibility problems of various devices, and is easy to upgrade and maintain in the future.