What is the transmission network? Different people have different answers. Some people may clearly understand the transmission equipment + lines, or many rings and chains. There is no standard answer to this question, but as a person who has just entered this field, there is a relative spectrum of understanding in the mind.
If the information is compared to the goods, the transport network is a logistics network. The logistics network bears services between enterprises and individuals. The transmission network carries information about each service network.
Fixed-line, mobile, broadband, data, softswitch, and VIP customers use the transmission network to exchange information between NEs. That is, we can make long-distance calls, send short messages, communicate with the Internet, and watch IP TV, this is implemented based on the large and complex transmission network.
The transmission network in our eyes is the access layer, convergence layer, and core layer.
The transmission network is connected to the fixed telephone network, mobile communication network, and broadband Internet through the isolated island of the global service layer. We use a familiar advertisement word. We do not produce information. We are only the porter of the communication system.
In my opinion, a transmission network is a reliable network for long-distance transmission of information.
Why do you say long-distance? If you want to give your office's colleagues or neighbors a thing, you don't have to call a courier company. In addition, the transmission of information does not require the transmission network. Generally, the interconnection in the equipment room can be directly interconnected. The network cable and 2M coaxial cable can be transmitted for about 100 m. The single-mode optical module can be used to transmit a dozen or even tens of kilometers, but hundreds of kilometers or even thousands of kilometers. There is no absolute boundary between far and near. As long as the service network whip is long, it must be handed over to the transmission network.
The other aspect is capacity. The service side can be directly connected through optical fibers within a certain distance. However, many professional optical fibers are directly connected. Therefore, a large number of fiber cores are consumed and the construction cost is high. This is similar to the fact that people do not pass the express company, but they drive by themselves, by train or by plane to deliver, it must not be more than a dozen dollars to be able to handle. A transmission network can carry a pair of fiber cores to carry 8T or even higher services. The higher the transmission efficiency, the lower the transmission cost of a single bit.
In addition, security is ensured. You do not want to lose your goods. The transmission network must ensure the security and accuracy of information transmission. Therefore, various fault tolerance mechanisms and protection switching must be provided to ensure security.
In fact, various technologies of the transmission network have been developed for decades to date. These key points are as follows: Capacity, security, and long distance.
