How to tell the network cable?

Currently doing network engineering time where a lot of twisted-pair, due to the cost and complexity of construction, the optical fiber is mainly used in backbone "fiber to the desktop," I am afraid that, in time, coaxial cable has basically been eliminated. UTP unshielded twisted pair is divided into (STP) and unshielded twisted pair (UTP) types, STP only in some special occasions (such as electromagnetic interference seriously, susceptible to corrosion chemicals etc.), with the most or UTP. From the actual experience of the author's point of view, the market now fake twisted pair (with someone else's trademark) even more than true, and false and true line-line also has the same tag. In addition to the false lines, There are many situations posing five lines, over five lines with three lines, it is necessary to explore the method of identifying network cables. First, to determine whether a fake foreign manufacturers. Domestic system integrators in general are using an overseas network cable majority, because that is the cable quality overseas than in most of the domestic cable quality is much better, the project is relatively easy acceptance, some domestic unscrupulous manufacturers began to imitate foreign network cable . How to check whether the network cable is not fake it? A customs inspection of IT technicians say a test method: Outside of foreign lines are very flexible plastic skin, the section of the network cable to the fold, if they can immediately rebound, basically that the network cable is authentic (Note: You can not fully guaranteed). Then determine the type of twisted pair. Twisted-pair cable wires in pairs, each two as a pair, and each other twisted. According to the American Wire Gauge (AWG) provides: twisted pair wires should all four pairs, a total of eight. However 10M Ethernet standards require the use of only two pairs of wire transmission signal, so 3 twisted pair is two pairs of some, while others are four pairs of. The emergence of Fast Ethernet, on the one hand, the original speed 10M network theoretically up to 10 times, on the other hand for the future faster networks (Gigabit Ethernet, transmission speed is 1000Mbps) prepare the simultaneous transmission speed of 100Mbps Category 5 twisted pair also put into use. Although Fast Ethernet uses only one of the two pairs, but Gigabit Ethernet must use to all four pairs. I suggest that you look at the label on the wire, as marked with the words "CAT3" The line is generally into three categories, described as 5 cable when marked with the words "CAT5" of, 5E words to 5e. Also the actual test its speed, because "posing" phenomenon also exists in the cable market. Now set up a network is generally used over Category 5 twisted pair, twisted pair is 3 products are eliminated. However, some manufacturers UTP Category 5 twisted-pair standard after launch, put the original 3 kinds of lines for wire enclosed in printed words Category 5 twisted pair cable sold. When you use this kind of false Category 5, the actual communication speed of the network can reach 100Mbps 5 twisted pair as defined in a very short distance. This fraud is very subtle, the average user is hard to find. In this case, it is recommended that you first buy some, use of Windows95 / 98 "System Monitor" or WindowsNTServer4.0 "Network Monitor" personal test. If the test speeds of up to 100Mbps, it indicates a Category 5 twisted pair, if only 10Mbps, description cables using Category 3 cable wire. This approach not only able to correctly distinguish three types of wire and Category 5 cable, and twisted pair cable can be used to test each pair of wires twisted around the degree of compliance with the standard, but also can measure the wire metal media is qualified. Note: During network speed test, the length of twisted-pair should be the standard length of 100 meters, otherwise the measured data without any practical significance. Finally, to test whether the network cable has some heat, tensile, bending and other easy-burning performance: First, you can be placed in high temperature environments twisted-pair test, really twisted pair at ambient temperature Celsius 35 ℃ to 40 ℃, the outside layer of rubber will not soften, and leave it will; the second, in order to ensure a secure connection, really twisted pair cable outsourcing has strong tensile rubber, and false but no; third, twisted-pair copper cable is generally used, and some manufacturers to reduce production costs, added to other copper metallic element which is a visual representation of adulteration lead after apparently normal ratio To hard, inflexible, prone to break in use; fourth, really twisted pair outside rubber also has anti-flammable, and false use ordinary combustible material may personally try the time of purchase. How to select the appropriate cable first to talk about is the use of STP, or UTP. This problem is more complicated, but also long-term dispute between manufacturers of issues. Because under what circumstances shielded, unshielded under what circumstances is difficult to clear. Later a domestic authority to determine a principle, mainly in the area of ??memory in which cabling electromagnetic interference field strength to determine whether to use STP, this indicator is 3 volts per meter. If less than 3 volts per meter, the choice of a non-shielded cable, or should use shielded cable, or the use of shielding measures or the use of optical fiber. The cable cloth on the metal pipe or duct and make sure the ground, or to increase the distance between the cable and interference sources can play a role in shielding. In fact in the project, the interference field strength greater than 3 volts per meter case little can be said that 90% of the occasions are less than 3 volts per meter. So we do not recommend you use shielded blind system, but from the actual situation. Because even higher than 3 volts per meter place to take certain measures to shield also reduces the impact of interference sources. Besides the current shielding effect for shielded cabling project test test standards and test instruments unresolved, use shielded system will naturally raise a lot of use of the project cost. Finally, to talk about in the end is 6 Gigabit Ethernet or fiber type of problem. If the network is the 100M Category 5 and 5e are the only choice, there is no need to use Category 6 or fiber; if the network is 1000M, in the end is 5E or Category 6 or fiber it? There was a lot of articles Category 6 cable is recommended, but I beg to differ, because one six cable connecting structure has not changed, and over Category 5 cable the same, but with the current widespread use of plug-in modules (RJ45) completely incompatible; Second, in spite of Category 6 cable rates up to 200M to 250M, but was much higher construction costs, construction difficulty is relatively high. Besides fiber prices now substantially reaches the user has to withstand the stage, so bandwidth requirements for high and well-funded enterprise, is recommended to choose fiber optic cabling to the desktop; funds are not very comfortable with the business in the Gigabit Ethernet basically 5E It will suffice. Now the development of cabling technology is basically half the emergence of a new hot spot, but I think the development of the cable must have a limit, use twisted pair cable transmission signal development principles into six categories almost to the end. With the development and wide application of fiber-optic technology, its price has shown a downward trend, coupled with the optical fiber cable having unmatched interference, security, high bandwidth and other advantages, it has become increasingly close to the user, but in the past the use of optical fiber trunk Compared to the situation, and now has been laying fiber to the building, the future may be direct to the home, its development prospects "light" Ming. As for category 6 copper, expensive (for the whole system, not only refers to itself twisted pair), and the installation process is complicated, for engineering and maintenance requirements, inconvenience universal application, it is unlikely to be widely used copper end, 5E most likely end. Because the structure of products and now 6 cabling products, the existence of a backward compatibility issues, and have brought a certain degree of difficulty of shielding products, will give construction. If the fiber and the optical / electrical adapter device development in accordance with current trends, the cost of further decline, perhaps six categories of products will be four categories of products and become as a transitional product. Wiring and push Gigabit cabling products manufacturers: one "5E"; the second is "6 class." The choice of products to calmly consider the choice of cabling system, the end result was determined by the application. Currently, Gigabit Ethernet is mainly used as a network backbone, it is difficult to say when the real to the desktop for the subsystem level, I am afraid that time, what products the situation has changed. Because copper eventually unable to go beyond their limited bandwidth, transmission distance and electromagnetic interference, replacing it will continue to be an optical fiber, or some future transmission medium. 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