The purchase of network cabling basic equipment

Today to introduce the network at the bottom (physical link layer) equipment in the cable, Crystal Head and socket module. This thing is small, but it cannot be neglected. These low-level devices are the link of the LAN transmission. In fact, many network failures are not because of network switches, routers, network cards and other equipment problems, but the cable, Crystal Head or socket module quality caused by poor. The network is not access or slow speed is mostly due to poor quality of the cable, high impedance signal attenuation caused by large. And in rainy weather often appear disconnection phenomenon, mostly because of the crystal Head or network module metal connectors Poor quality, there is mildew caused by the phenomenon. In the market, the transparency of such products is not too high, many brands, it can be said that the quality is uneven. As far as the XI ' an market is concerned, there are Ampcerda, Ampsan and, Ibmnet, Shaanxi Tong, Hanwei and so on, Jin Lang, Tp-link and so on also launched their own network cable, if you do not know much about this line, the network of the brand is enough to you dizzy, in fact, Ampcerda, Ampsan and these are disguised as amp Second-line products of the name. "Ibmnet", many attractive names, sell you a 240, you must be happy to fart. At present, large shipments of AMP amp, Lucent Avaya, Simon Xiemon, Ibdn, and other brands of wire products, each face of the fake to its market. So, the merchant said "original XX line", may not be original, how to polish your eyes, distinguish between good and false? Below, we will separately on these three kinds of network accessories should pay attention in the purchase aspect to introduce:

Cable purchase
Twisted-pair lines according to the electrical performance of the division, usually divided into: three categories, four categories, five categories, five categories, six categories, seven types of twisted pair, such as the number of large, version of the newer, more advanced technology, the wider bandwidth, of course, the price is more expensive. Three categories, four types of lines at present in the market almost no, if there is not a three-class or four-class line appears, but false to five categories, or even five-class line for sale, which is currently false five types of line. At present, the common LAN is five categories, Super Five class or six types of unshielded twisted-pair, fig. 1 shows the left image is a section of unshielded Super Five type of two-line schematic diagram, and the right is a section of shielded twisted pair. As you can see from the diagram, shielding five types of twisted pair of bread has a layer of shielding metal film, its anti-interference performance is better, but the application of the conditions are more stringent, not shielded twisted-pair, in the anti-interference aspect must be stronger than the unshielded twisted-pair line. Shielding of twisted-pair wires only has shielding device in the whole cable, and it only works when the two ends are grounded correctly. Therefore, the requirements of the entire system are shielding devices, including cables, sockets, crystal head and wiring racks, and the building needs to have a good ground system. In fact, in the actual construction, it is difficult to all perfect grounding, so that the shielding layer itself into the largest source of interference, resulting in performance even far less than the unshielded twisted UTP. Therefore, unless there is a special need, usually in the integrated wiring system only the use of unshielded twisted-pair cable. ---http://bianceng.cn (computer science)

Figure 1
As a kind of low price and good performance transmission medium, twisted pair is widely used in the cabling system. Twisted-pair wires are inexpensive, reliable and easy to maintain, provide up to 1000Mbps of transmission bandwidth, not only for data transmission, but also for voice and multimedia transmission. The current super five and six-class unshielded twisted pair can easily provide 155Mbps of communication bandwidth and have the potential to upgrade to gigabit bandwidth, thus becoming the preferred cable for today's horizontal cabling.

In different brands, we see the most in the market or amp (AMP), almost every network cable operators can see its figure, its biggest feature is the quality of good, cheap, the whole box to buy, usually authentic Ampshu double stranded line per meter is only about 1.5 yuan. is so popular, so its fakes are the most, some to almost the real, it is difficult to distinguish between true and false. According to the author's procurement experience, in the AMP line purchase has accumulated the following experience:

First from the network cable identification, three types of line identification is "CAT3", bandwidth 10M, applicable to 10 trillion nets, the current basic has been eliminated; five types of line identification is "CAT5", bandwidth 100M, applicable to the network under hundred trillion; the logo of Super Five line is "CAT5e", bandwidth 155M, is the current mainstream product Six line identification is "CAT6", bandwidth 250M, used for erecting gigabit network, is the trend of future development. Second, by looking at this approach we can identify most fake 5 class/Super 5 line. The real 5 line of online plastic wrapping on the printed characters is very clear, sleek, basically without jagged. Fake handwriting printing quality is poor, some fonts are not clear, and some are seriously serrated. Authentic 5-Class line is labeled "Cat5", the Super 5 category is labeled "5e", and fakes are usually labeled with uppercase letters "such as CAT5", "5E" words.

Standard five-class line
Feel again with the hand, if through "see" method still cannot discriminate, can further through "touch" method to feel true or false 5 class/Super 5 type line in the material difference. True 5 class/Super 5 line texture is relatively soft, this is mainly in order to adapt to different network environment requirements, twisted-pair cables generally use copper wire to do the conductor core, relatively soft (because some network environment may require a small angle cable for bending, if the wire is hard and easy to cause circuit breakers.) While some unscrupulous manufacturers in the production in order to reduce costs, in the copper added other metal elements, made out of the wire is more hard, not easy to bend, use easy to produce disconnection.

Then cut with a knife, this step only with scissors to remove a small cut line outside the plastic foreskin, exposing 4 pairs of core line. Here, we still use the "see" method to further discriminate, real 5 class/Super 5 line 4 on the core line white that should not be pure white, but with the pair of the core line color of the gray, this is mainly to facilitate the user in the production of Crystal head when the difference between the line pair. Fakes are usually pure white or are not of obvious color. Another point is 4 to the core wire winding density, true 5 type/Super 5 type wire winding density moderate, the direction is counterclockwise. The false line usually has a small density and the direction may be clockwise (less), mainly because it is easier to make, so the production cost is small.

Finally, with the fire, you can test the twisted pair in a high temperature environment look at 35 ℃ to 40 ℃, the network cable will not be soft, genuine network cable is not soft, false is not necessarily; there are real network cables outside the rubber is also a flame retardant, and some of the false does not have fire resistance, not in line with safety standards, You may try it when you buy.

The above few strokes are far from being able to deal with all the counterfeit network cable, and some counterfeiters use three lines of wire core set on the five types of line of the skin, this means of counterfeiting is very covert, the naked eye is also difficult to distinguish. This kind of false network cable can reach the transmission speed of five kinds of line in a short distance, but when the distance is long, the transmission speed is slow, the transmission packet is lost or the signal can't be detected simply. For this, you can take a network of cable to test: Take a 100-meter network cable to the computer network, using Windows 98, "System Monitor" or "Network Monitor" in Windows 2000 to personally test, if the test speed reached 100Mbps, it is 5 types of twisted pair, If only 10Mbps, it is indicated that the cable used is a 3 line wire. This method can not only correctly distinguish 3 types of lines and 5 types of lines, but also to test the twisted wire of each pair of cables in the twist to meet the standard, at the same time can be measured wire in the metal medium is qualified. Note: In the network speed test, the length of the twisted pair should be the network cable itself within the standard length range, otherwise the data measured without any practical significance.

Of course, these test methods, and not necessarily receive very good results, counterfeiting means of continuous improvement, making consumers more and more difficult to distinguish between authenticity. To deal with fakes in addition to consumers themselves to improve the ability to identify, but also manufacturers to make unremitting efforts. However, in general, choose a brand of network cable and carefully screened to maximize the protection of our interests. Most of the manufacturers have in the field of precision cable super large-scale production capacity, in order to ensure the quality of the premise, the price can be significantly reduced, so that counterfeiters are difficult to profit. For example, the well-known Foxconn (Foxconn) Company's cable products used this way, the current market has not found the counterfeit network cable. Thus far, making counterfeiters unprofitable remains one of the most effective ways for manufacturers to deal with counterfeit products.

Finally give a first-line brand product retail quotes, we can compare when you buy, if the price difference is larger, it is the possibility of real goods is not big, I always believe that "cheap no good goods."

Cable Quotes
See, the market on the 3XX "original amp line" or false. There are market Tp-link, Jin Lang and other brands, many are OEM, the price is generally around 280, the quality can be counted.

RJ-45 Crystal Head
In all the network products, the crystal head should be the smallest equipment, but it plays a very important role, so in the choice can not because of small and despise it.

Crystal Head
From the price, the current market quality of poor crystal head more. Generally only 0.5 yuan. Authentic goods in general more than 1 yuan

Look at the Appearance:

First, the shape of the crystal head should be compatible with the network card or the corresponding interface on the hub;

Second, the Crystal head front of the metal pressure line shrapnel should not only have strong hardness, two and should also have a very good toughness. When the hardness is poor, the metal shrapnel can not be inserted into the twisted pair wire, the crystal head will not function, when the toughness is not up to the requirements, the metal shrapnel fracture easily;

Third, the crystal head on the back of the plastic shrapnel should have a good elasticity to ensure that the crystal head and equipment very good contact. You can try, if the insertion of a crisp sound, indicating good elasticity;

Four, twisted-pair connection head in the production to use a special clamp to make, so the requirements of the crystal head of the material should have a good plasticity, in the suppression will not appear fragmentation phenomenon. These characteristics, most of the fake crystal head is not available.

Distinguish between true and false crystal head apart from the above method can also be judged by "see" this method. Genuine contact copper piece color bright, and relatively thick, the whole component is also relatively sufficient. The fake is the opposite, the color is dim, the metal contact piece is also thinner. If the inventory time is longer, you may also see rust.

In addition, the "scraping" method can be used to discriminate, we can use a small blade gently scraping crystal head of the metal contact, if found that the surface of copper plating is easy to drop, the inside exposed black parts, it is certainly false. Genuine surface Plating copper layer is usually not easy to drop, even if a little off, the inside of the exposed metal contact is white and bright.

Module
Here the author of the module is a general term, in fact, there are information outlets and cable modules composed of two parts.

1: Information sockets are generally installed on the wall, so is also called the Wall box. There are also desktop and ground-type, mainly to facilitate the movement of workstations, and to maintain the overall layout of the beautiful. This kind of product price difference is great, the copper inserts generally in 100 above, the ordinary only a few corners.

2: Network cable module: With the information plug is the network cable module, this module is installed in the information socket, usually through the card bit to achieve, through it from the switch out of the network cable and a good crystal head to the workstation end of the cable connected.

Authentic Socket Module
This kind of product in the market is also the majority of fakes. If you can buy it at just a few dollars, it's probably fake. The real thing is usually more expensive and requires more than 20 yuan. So now the usual network people still prefer to buy a motley, because in the price difference is too big. Why such a small attachment true, fake prices are so big difference? That's because the module uses a lot of metal shrapnel, the real to ensure that these pieces of metal with good elasticity and contact properties (mainly refers to contact resistance), the material used is usually better, and the gold-plated is also more expensive. Of course, the material and performance of fakes are much worse. I have done this experiment, is also in two true, false modules installed/plug network cable, fake after many plug and pull out after some of the shrapnel contact bad, and the genuine after the same number of plug still contact good.

Module quote
Of course, these fake modules can also be distinguished from the appearance. The genuine metal parts are shiny, and the metal plate is more generous, and the fakes are relatively dim, the metal sheet is relatively narrow and thin. In terms of elasticity, we can use tweezers test dial can be verified, authentic elasticity is good, not easy to deformation, and fakes lack of elasticity, and in a larger curvature may be deformed.
　　
Here are some of the more famous brands to choose from, such as Qi Sheng, TCL, AMP, Avaya, etc., in the purchase time can also go to their stores to buy. In fact, the module installation when indispensable to use dedicated line-playing tools, "工欲善其事 its prerequisite" Well, good tools really have a multiplier effect oh.