Shulou(Shulou.com)11/24 Report--

Slow Internet access, offline video games, video conference stutter, these moments of being held back by the scum network speed, are you thinking: is it the pot of the router, or the broadband is not powerful?

But in fact, it is also possible that the network cable is not selected correctly.

In the network signal transmission link, the network cable is the most easily neglected link. However, the network cable is the bridge connecting various devices, if the network cable selection is not good, it will also affect the network data transmission speed of the devices at both ends.

For example, the router is 1000Mbps, the broadband is 500Mbps, if the network cable used is 100Mbps, then the final network speed is only 100Mbps.

Network cable classification at present, the network cables on the market are mainly divided into: Super five categories, six categories, super six categories, seven categories, eight categories. Five types of and previous network cables have been gradually eliminated by the market because of their low data transmission rate and can not meet the requirements of home broadband.

There is a CAT.5E mark on the outside of the super five network cable, and the maximum transmission frequency is 100MHz, which can meet the transmission rate of 1000Mbps within 100m, which is suitable for gigabit network.

There are CAT.6 marks on the outside of the six types of network lines, and the maximum transmission frequency is 250MHz, which can meet the transmission rate of 1000Mbps within 100m, and is suitable for gigabit networks. In order to better reduce crosstalk, most of the six types of network wires have added a cross insulation skeleton, and compared with the super five, the six types of wire core diameter is larger, the stable transmission distance is longer, and the performance is better. Qualified Category 6 lines can support 10 Gigabit networks within 55 meters.

There is a CAT.6A mark on the outside of the super-type 6 network cable, and the maximum transmission frequency is 500MHz. The maximum transmission rate can reach 10Gbps within 100m, which supports 10 Gigabit networks.

Super Category 5 network cable is CAT.5E, Super Category 6 network cable is CAT.6A. As for some network cables marked as CAT.6E, which do not belong to the standard network cable category, the transmission performance can not be guaranteed. Please pay attention to the identification.

There is a CAT.7 mark on the outside of the seven types of network lines, and the maximum transmission frequency is 600MHz. The maximum transmission rate can reach 10Gbps within 100m, which supports 10 Gigabit networks. Seven types of network cables are forced to increase double shielding, which can better combat signal attenuation and crosstalk.

There are CAT.8 marks on the outside of eight types of network cables, the ultra-high broadband of 2000MHz, and the maximum transmission rate can reach 40Gbps, but it is only limited to 30 meters, so it is generally used for the connection of short-distance servers, switches, distribution frames and other equipment.

The network cable shielding type mentioned above is twisted pair, which is formed by a pair of insulated wires winding each other counterclockwise. This mutual winding method can reduce the signal interference, and the denser the wire winding is, the stronger the anti-interference ability is.

In order to further strengthen the anti-interference ability, some network lines will also add a shielding layer, according to whether there is a shielding layer, the network cable is divided into shielded twisted pair (STP) and unshielded twisted pair (UTP).

Shielded twisted pair (STP) shielded twisted pair is to add one or more metal shielding layers to the insulation sheath. Metal shielding layer can reduce radiation and anti-interference, which can not only shield the external electromagnetic signals, but also block the electromagnetic leakage of the cable itself, so the twisted pair with shielding layer has higher signal transmission quality and good security performance. However, the price of the shielding line is higher, and the installation process is more complicated.

The double shielding mentioned above means that each pair of wire cores has an independent shielding layer, and the outer layer shares one or more shielding layers. As shown in the figure below, each pair of core wires has an aluminum foil shield to reduce signal attenuation and crosstalk, and an outer layer of metal braided shielding, which can reduce the interference of external magnetic field and signals, and increase the tension of the cable.

Unshielded twisted pair (UTP) unshielded twisted pair is wrapped with only one layer of insulating rubber sheath and no metal shielding material. The utility model is characterized by light weight, small overall wire diameter, easy to bend, flexible networking and relatively cheap price.

The national standard wire core is oxygen-free copper with a purity of more than 99.95%, but the higher the purity of copper is, the higher the cost of the wire is. Therefore, there are many non-standard network wires on the market, including iron and aluminum, copper-clad aluminum, high conductivity aluminum, copper-clad silver and copper-clad copper wire.

The material of the network cable will affect the transmission quality and service life of the network cable. It is mainly reflected in the following three aspects:

Resistor size. The lower the resistance, the higher the transmission rate and the longer the transmission distance.

Tensile strength. Network cable installation and use need a certain tensile strength, can not pull and swing a few times to break.

Antioxidant activity. Strong oxidation resistance means not easy to rust and long service life.

The following table shows the performance comparison of several wire materials, comparing the wire performance of the core diameter 0.5mm. Generally, the larger the core diameter is, the smaller the resistance will be and the longer the transmission distance will be.

The resistance of 100 meters iron-aluminum mesh wire is about 50 Ω, which can transmit about 60 meters at most, and the transmission quality is relatively poor, so it is not recommended.

Copper-clad aluminum, high conductivity aluminum and copper-clad silver mesh wires are all made of aluminum, which are coated with oxygen-free copper on the surface of aluminum or aluminum alloy core to improve transmission performance. Among them, the purity of aluminum wire used by copper-clad aluminum is the lowest, the price is also relatively cheap, and the transmission distance can reach 100 meters. The purity of copper-clad silver aluminum wire is the highest, the resistance is the lowest, and the transmission distance is the farthest, which can transmit 150-180 meters.

The transmission of aluminum wire is relatively stable and the communication distance is long, but the oxidation resistance of aluminum is poor, so the service life of aluminum wire is short, which is not conducive to long-term use. And the tensile strength of aluminum wire is not as strong as that of copper conductor, so great pulling should be avoided in the process of use.

Copper-clad copper and oxygen-free copper are copper mesh wires, which have strong oxidation resistance and high tensile strength. Copper-clad copper mesh wire is coated with oxygen-free copper on the outside of bronze, also known as pure copper mesh wire, but in fact bronze belongs to secondary recycling copper, the purity is not high, the resistance is high, 100 meters resistance is about 40 Ω. Oxygen-free copper wire, also known as original copper wire, is made of pure copper conductors with high conductivity and long signal transmission distance, so it is a kind of high quality wire.

Therefore, the comprehensive properties are as follows: oxygen-free copper > copper-clad copper > copper-clad silver > high conductivity aluminum > copper-clad aluminum > iron and aluminum.

How to choose a sentence to summarize the above: the higher the level of the cable, the better the material used, the larger the diameter of the wire core, the more additional components (shielding, cross skeleton, etc.), the better the performance, and of course, the more expensive it is.

When we choose the network cable, is it better to buy the more expensive it is?

If the shielded network wire is selected, it can play a positive role only if both ends of the network cable are grounded correctly, which requires that the network equipment, crystal head, distribution frame and port on the line can be grounded, and the building itself also has a good grounding system. the shielded wire can shield the interference and ensure the transmission performance. If the grounding is improper, the shielding layer may introduce interference and become the biggest interference source of the transmission line itself.

Due to the use of double shielding, the overall wire diameter is thick, the overall network cable is very stiff and not easy to bend, the wiring and construction is difficult, and the cost is high, so it is generally used as a jumper, which is suitable for use in the computer room, but not for household use. And there is no complex strong interference in the home environment, short-distance transmission of more than five types is enough. If you want higher speed and longer stable transmission distance, you can choose Category 6 or over Category 6 unshielded lines.

To sum up:

If the network cable being used, or the network cable pre-buried for decoration in earlier years, it can be replaced.

For household use, it is recommended to choose more than five, six or more than six types of unshielded wires. If we choose the shielded wire, we need to deal with the grounding problem of each equipment and port.

Material, temporary use of external network cable, copper-clad aluminum or above can be used. Home improvement pre-embedded network cable, not convenient to replace, the preferred national standard oxygen-free copper mesh wire.

Choose the brand network line that is sold through regular channels. A network cable bought casually by a roadside shop may not even have a formal logo, and its quality can not be guaranteed.

This article comes from the official account of Wechat: ZTE document (ID:ztedoc), author: ZTE document

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.