In network hardware, there is another type of network transmission medium that cannot be ignored, which is usually called network cable. At present, the more common network cables are divided into thin twisted pair, fiber optic cable, coaxial cable and thick coaxial cable.

1. Optical fiber cable

Fiber optic cable is a new generation of transmission medium. Compared with copper medium, optical fiber has been greatly improved in terms of security, reliability and network performance. In addition, the bandwidth of optical fiber transmission greatly exceeds that of copper cables, and the maximum connection distance it supports is more than two kilometers, which is an inevitable choice for building large-scale networks. Because the fiber optic cable has the advantages of good electromagnetic interference resistance, strong confidentiality, fast speed, and large transmission capacity, its price is also relatively expensive, and it is rarely used in household occasions. There are two different types of optical fibers that are more common at present, namely single-mode optical fiber and multi-mode optical fiber (the so-called "mode" refers to a beam of light entering the optical fiber at a certain angle). Multimode fiber is generally used for network connections within the same office building or within relatively short distances. Single-mode fiber, on the other hand, delivers higher quality data and longer distances, and is often used to connect networks between office buildings or more geographically dispersed networks. If the optical fiber cable is used as the network transmission medium, it is necessary to add equipment such as optical transceivers, so the cost is higher, and it is less used in general applications.

2. Twisted pair

Twisted pair is a flexible communication cable that contains pairs of insulated copper wires. It is characterized by low price, so it is widely used, such as our common telephone lines. According to the difference of the maximum transmission rate, twisted pair can be divided into Category 3, Category 5 and Category 5e. The rate of Category 3 twisted pair is 10mb/s, Category 5 can reach 100mb/s, and Category 5 is up to 155mb/s or more, which can meet the needs of future multimedia data transmission, so Category 5 or even Category 5 double is recommended. Stranded. Twisted pair can also be divided into shielded twisted pair (stp) and unshielded twisted pair (utp). Although the rate of stp twisted pair is lower (only 4mb/s), its anti-interference is stronger than that of utp twisted pair, so the price is also much more expensive. Now this kind of twisted pair is cheap a few yuan per meter, and it may be expensive. You can buy a meter for more than ten yuan. In contrast, the price of utp twisted pair is generally about one yuan per meter, which is relatively low. In addition, the popular names of the commonly used 10m and 100m unshielded twisted pair are 10base-t and 100base-t, which are often seen in the market. The rj45 crystal head is also used in conjunction with the twisted pair, which is used to make the joint between the twisted pair and the rj45 interface of the network card. Its quality is directly related to the stability of the entire network and cannot be ignored.

3. Coaxial cable

Coaxial cable is a kind of transmission medium that many friends are familiar with. It is a cable with a central copper conductor wrapped by layers of insulated wires. Its biggest feature is good anti-interference ability, stable data transmission, and cheap price. , so it was once widely used, such as CCTV lines. However, coaxial cables were used more in the past, mainly because the cost of the bus structure network composed of coaxial cables is low, but the damage of a single cable may cause the entire network to be paralyzed and difficult to maintain, which is its biggest drawback. Coaxial cables in Ethernet applications are mainly divided into thick coaxial cables (10base5) and thin coaxial cables (10base2). Thick coaxial cables are not used much anymore, and there are still some markets for thin coaxial cables. The thin coaxial cable is generally sold for a few yuan per meter in the market, which is not too expensive. In addition, the coaxial cable is used to connect with the bnc head. The coaxial cables sold on the market are generally finished products that have been connected to the bnc head, and you can use them directly.