Classification of twisted pair wires and identification of cat-5e wires

With the release and Implementation of the Fast Ethernet standard, cat5e twisted pair wires have been widely used in network cabling. However, due to the misleading publicity by some vendors and network companies, and the lack of necessary knowledge about related standards by some network users, it is hard to identify the true and false of the cat5e twisted pair. However, the selection of non-compliant cat5e twisted pair wires will, on the one hand, reduce the overall performance of the network, and on the other hand, pose a hidden risk for future network upgrades. This article introduces the correct identification method of standard cat5e twisted pair wires based on technologies and applications.

To give you a comprehensive understanding of twisted pair wires, let's first introduce common types and features of twisted pair wires. Twisted Pair wires in computer LAN can be divided into two categories: unshielded twisted pair wires (UTP) and shielded twisted pair wires (STP). STP is enclosed by a layer of metal material to reduce radiation and prevent information eavesdropping, at the same time, it has a high data transmission rate, but the price is high and the installation is complicated. UTP has no metal shielding material and only one layer of insulation rubber package. The price is relatively low and the networking is flexible. Except for some special occasions (such as serious electromagnetic radiation and high transmission quality requirements), STPS is used in cabling. In general, UTP is used. Currently, the UTP can be divided into three categories: Class 4, Category 5, and Category 5. Among them, three types of UTP adapt to the requirements of Ethernet (10 Mbps) for transmission media and are important transmission media in the early network. Four types of UTP are later than three categories due to standard release, the transmission performance is not much higher than that of the three types of UTP, so it is generally used less. The five types of UTP have become the preferred medium for Fast Ethernet (100 Mbps) because of its low price and high quality; the Application of cat5e UTP is Gigabit Ethernet (1000 Mbps ). Based on the actual needs of current network cabling, this article mainly introduces the correct identification and selection of five types of UTP.

1. transmission speed

The quality of twisted pair wires is one of the key factors that determine LAN bandwidth. Some manufacturers wrap line pairs used in Class 3 or Class 4 UTP cables in Category 5 UTP, which is difficult to identify for general users. The so-called "five types of UTP" cannot reach a data transmission rate of Mbps, and the maximum is 10 Mbps or 16 Mbps. A simple identification method is to use a twisted pair to connect two Mbps devices (NIC to NIC or Nic to HUB ), use the monitor detection tool provided by Windows 95/98 to monitor the data transmission rate during communication. Method: ① Select Start> program> attachment> System Tool> system monitor. The system monitor window appears. If the "System Tool" does not contain the "system monitor" tool, you can create it through "My Computer> Add/delete Programs> Windows Installer> System Tool> system monitor. ② Set monitoring objects in the system monitor window. Select the "add project" option in the "edit" menu, and select "Microsoft network server" or "Microsoft Network Customer" in the "category" List of the displayed dialog box (note: in the next dialog box, select "number of bytes written/second" or "number of bytes read/second ". You can choose either "Microsoft network server" or "Microsoft Network Customer", "number of bytes written/second" or "number of bytes read/second, because the data sent from one node in the network should be equal to the data received by another node. ③ Set the output mode of test data. The system provides a line chart, bar chart, and number output mode, which can be selected through the buttons in the toolbar of the window. ④ Perform the test. The most effective way is to copy a large number of files from the server to the workstation you are testing (to test the accuracy, the copied content must be enough ). Generally, if the displayed peak value is more than 4 Mb/s, it can basically be five types of network cables (the peak value of the three types of lines is about 2.5 Mb/s ).

2. the twisted pair of twisted pair in the cable should meet the requirements

To reduce signal interference, each line of the twisted pair cable is twisted by two insulated copper wires, in addition, different cable pairs have different degrees of twisting (that is, the number of twisting coils), as shown in 3. At the same time, the line pairs in the standard twisted pair cables are twisted counterclockwise. However, some non-formal cable manufacturers have many problems: ① To simplify the manufacturing process, the cable has the same twisting density; ② The twisting density of the two insulated wires does not meet the technical requirements; ③ the twisting direction of the wire does not meet the requirements. If the above problem exists, it will cause the near-end Crosstalk of the twisted pair (the degree of signal interference between two pairs in UTP), so that the transmission distance does not meet the requirements. The twisting degree of twisted pair wires has strict standards in production. In actual purchase, some professional equipment can be used for measurement under conditions, but generally users can only observe it with the naked eye. It should be noted that the twisting degree of the five UTP midline pairs is better than that of the three types, and that of the Super five types is better than that of the five types.

In addition to the two insulated copper wires that constitute a twisted pair, the cable pairs in the standard twisted pair must be twisted in a clockwise direction. Otherwise, the cable resistance will not match and the transmission distance will be limited. This is rarely noticed by the 1.1 users. For information about the twisting and other related parameters of cat5e twisted pair cables, refer to TIA/EIA 568A (TIA/EIA 568 is the wiring standard set by ANSI in 1996, this standard describes the infrastructure related to network cabling, including cables and connecting devices. The letter "A" is represented as IBM's cabling standard, while AT&T uses the letter "B .) .

3. How many pairs of cat5e twisted pair?

When using twisted pair wires as transmission media, Ethernet only needs two (4-core) pairs to send and receive signals. There are three standards for Fast Ethernet using twisted pair wires as transmission media: 100Base-TX, 100Base-T2, and 100Base-T4. Among them: 100Base-T4 standard requires the use of all 4 pairs of lines for signal transmission, the other two standards only require 2 pairs of lines. The 100Base-TX standard is the most popular in Fast Ethernet. Therefore, when purchasing a m twisted pair, do not use a twisted pair with only two wires at a low cost. Category 3, category 4, Category 5, and Category 5 twisted pair wires are defined as 4 pairs in the US cable standard (AWG). In Gigabit Ethernet, all four pairs of cables are required for communication. Therefore, there should be four pairs of cables in the standard category 5.

4. Observe carefully

After having the above knowledge, you should also pay attention to the following points when identifying the five types of UTP: ① view the description information outside the cable. The outer foreskin of the twisted pair CABLE should be printed with "amp systems cable ...... 24AWG ...... CAT5 indicates that the twisted pair is the cat5e twisted pair of the company (the most prestigious twisted pair brand), where 24AWG indicates the twisted pair used in the LAN, CAT5 indicates the cat5e; in addition, there is a NORDX/CDT company's IBDN standard five network cables, the above words are "ibdn plus nordx/CDX ...... 24 AWG ...... "CATEGORY 5". The "CATEGORY 5" here also represents the five CATEGORY lines (CATEGORY indicates the English "CATEGORY ). I have used a box of so-called Five-category cables without classification, and have been tested to only meet the standards of Three-category cables; ② is it easy to bend. Twisted Pair wires should be bent naturally to facilitate cabling; ③ whether the copper core in the cable has good toughness. In order to ensure that the twisted pair wires are not broken during movement, except for the skin protection layer, the internal copper core must have a certain toughness. At the same time, for the convenience of joint production and reliable connection, the copper core can neither be too soft nor too hard, too soft is not easy to make the joint, too hard is prone to joint fracture; ④ whether it is flame retardant. In order to avoid cable damage caused by high temperature or fire, in addition to good tensile properties, the outermost layer of the twisted pair should be flame retardant (you can use fire to burn the test: if it is genuine, the rubber skin will be heated and soft, will not fire; if it is fake, a little ). In order to reduce manufacturing costs, non-standard twisted pair cables generally use non-conforming materials to make the foreskin of cables, which is not conducive to communication security.

Varieties of twisted pair wires:

1.100 Ω shielded cable: Category 5, 4 to 26AWG shielded cable, Category 5, 4 to 24AWG 2.100 Ω unshielded cable: 7 category cable: 1 pair 19AWG unshielded Cable Category 6: 4 pairs of 24AWG unshielded cables, 4 pairs of 23AWG unshielded cables, 25-to-22AWG unshielded Cable 5e type: 4 pairs of AWG unshielded Cable Category 5: 4 to 24AWG, 4 to 24AWG unshielded cable, 25 to 24AWG unshielded Cable Category 4: 4 pairs of 24AWG unshielded cables and 25 pairs of 24AWG unshielded Cables Category 3: 4 pairs of 24AWG unshielded cables and 25 pairs of 24AWG unshielded Cables Class 2: Speech and low-speed transmission Class 1: Basic Communication 3. Dual-body cable: 24AWG unshielded 4/4 pairs, 24AWG unshielded/shielded 4/4 pairs, 24/22 AWG unshielded/shielded 4/2, 24AWG unshielded 2/2 Pairs 4.150 Ω shielded cable: Type 1A, type 6A, and type 9A