Comprehensive Analysis of ingress testing in Integrated Wiring System Testing

Before giving you a detailed introduction to the test of the Integrated Wiring System, let us first understand the entrance test of the Integrated Wiring System test. This is a very important preparation in the test, this article will focus on this step, and I believe you will have a deeper understanding of the entrance test after reading this article.

Before formal construction, the feasibility of the cabling system should be preliminarily evaluated to ensure the health of the cabling system. This is called the entrance test of the integrated cabling system test.

Cabling systems are mainly divided into bare cable, jumper, module, and external crosstalk tests. Due to technical complexity, Module Testing is mainly used in laboratory technical models, mainly for cabling system manufacturers, while the other three are currently common in-site testing technologies for Integrated Wiring System testing. So how can we conduct qualitative and quantitative checks on these factors before construction? This article will be divided into Cable Testing, jumper testing and external crosstalk testing for a detailed introduction.

1 pre-construction test: FCL cable test

Currently, most data center cabling systems are composed of optical fiber cables and twisted pair wires. Optical fiber is mainly used to connect storage devices and servers. Twisted Pair wires are mainly used to connect physical devices and servers and interwork with switching devices. The use of twisted pair wires accounts for 70% of the data center cabling system ~ 80%. The quality of the twisted pair directly affects the quality of the data center cabling system. Ensuring the twisted pair Quality is a key point to improve the quality of the cabling system.

Considering the data center transmission rate requirements, most of Party A will require the project implementers to use famous brands or well-known cables on the market. However, the market is filled with cables of various brands. The price gap is very large, and the quality is also very different. When ordering twisted pair wires, customers often encounter such a situation. If the customer requires a line of a certain brand, sellers often ask which brand line they need: average quality, good or best? The best of course is the most expensive and most likely a brand line. The general or good quality may be the imitation of some small factories in China. Although the core technology of twisted pair cables is in the hands of some large manufacturers, it is easy to copy from the basic appearance style, if it is not difficult for a professional to see the difference between products of a big brand and fake lines, this is also one of the reasons for the proliferation of fake lines. A major difference in prices is the use of materials. Many informal manufacturers add some aluminum and iron to the copper core to save material costs. The addition of aluminum and other low-cost metals greatly hinders the transmission of high-frequency signals, especially affecting the transmission rate. There are also some technical differences. For example, in order to reduce the crosstalk between each other and interfere with each other between the 4 pairs of twisted pair wires, the gap between the balanced wires must be inconsistent. The higher the frequency of transmission, the greater the mutual interference between line pairs. Different levels of twisted pair wires have different twisting rates. This technology is also one of the core technologies of well-known cabling brands.

The so-called "General brand", "better brand", and "real brand line" cannot be determined with the naked eye during cable procurement. Due to Party A's lack of understanding of the cabling market or information asymmetry, Party A cannot learn the quality of the cables used before installation. Therefore, some bad Party B will win the bid at a low price and use fake brand-name cables to maximize the benefits. Therefore, Party A needs some effective means to supervise Party B, and Party B also needs to prove the quality of the materials used by Party.

2. How to perform Cable Entry Testing

Fortunately, in the cabling industry, the quality standards for cables are already available, such as TIA 568B and ISO 11801. After selecting the cables, the customer selects several m long cables from the cables delivered by the project team for testing. Because the link density and total number of data centers are relatively large, most of the products purchased in batch are checked by warehouse receiving. The proportion of the tests is from 2% ~ 20%, which is closely related to the total number of purchased products, the contract inspection ratio of Party A, and the degree of attention of Party A on product quality. Of course, the customer is conducting Cable Testing, you must use a test instrument that supports the cable test standards in TIA 568B, such as the "DTX1800 cable analyzer" + "cable test adapter" LABA "pair + DTX-REFMOD module, after selecting a m twisted pair, follow these steps to test the cables before installation.

1) device calibration. Use the calibration module provided by the instrument to calibrate the host and the remote end to eliminate errors between the testing instrument.
2) connect to the dedicated cable test adapter. Insert the laba mn module on the host and far end.
3) connect to the tested Cable
4) Select the test standard. Select a dedicated test standard for twisted pair wires in the host. Take the 6A line as an example, select TIA Cat.6A cable 100mLA ).
5) Test the Integrated Wiring System. The Instrument Automatically completes the test item according to the standard. Check the test result after 9 seconds and check whether the twisted pair wires are qualified.
6) generate a test report. Because DTX series instruments support digital signal processing technology, the frequency domain signal is converted into a time domain signal through Fourier inverse transformation and transformation. After the strong interference signal received from the two ends of the M line is removed from the time domain, reconvert to a frequency-domain curve. In this way, the standard test is completed accurately to identify the performance of the cable.

3 pre-construction test: jumper Test

In the cabling system of the data center, a large number of jumpers are used to achieve fast interconnection between switch devices or server connections. Frequent plugging and repeated use, patch cords with poor quality often make the jumper a fault point in the data center. Experienced data center maintenance personnel discard some patch cords that are repeatedly used multiple times and replace them with new ones. In the past, maintenance personnel often used replacement methods to ensure the quality of jumpers.

With the increase in data volumes in the data center, the requirements for the transmission bandwidth of the cabling system have also increased. The use of cat6 and cat6 links has become increasingly popular in data centers. Maintenance personnel found that patch cords are increasingly becoming fault points. Sometimes replacing a new 6-category patch cord will also be the bottleneck of the entire Link, and 80% of the Jumpers made by experienced maintenance personnel will encounter various problems. Jumper itself is short, most of the Jumpers do not exceed 5 m, more than 10 m is a long jumper. Therefore, the cable itself has little impact on the jumper quality, and the quality of the crystal head and its end connection is the key to Jumper testing. As the transmission frequency increases, MHz or even higher, there is a higher requirement on the end connection when the cable supports the transmission rate. In short, when the twisted pair is inserted into the crystal head, a large deformation occurs, for example, the twisted pair is separated, which will cause a sudden change in the characteristics of the cable. Such as ripple loss, the crystal head becomes the bottleneck of High-speed transmission. Needless to say, there is a high percentage of unqualified jumpers directly pressed by many famous manufacturers by machines. I once had the opportunity to test 10 categories of 6 jumpers from a major manufacturer, one of which is unqualified, and the other is just stuck with a qualified line, leaving a very small margin. Therefore, both the patch cord from the manufacturer and the manual patch cord must be tested before installation to ensure the quality of the data center cabling system.

4. Misunderstanding of jumper test: replacing jumper test with Channel Test

Currently, in the industry, many integrators or engineering construction parties use Channel Test Modules to detect jumpers. The test results were satisfactory and were hardly rejected. In fact, the fault point of jumper is usually on the crystal head rather than the cable. However, the standard stipulates that the channel test model does not include the crystal headers at both ends of the link. That is to say, the effect of the crystal headers at both ends of the link will be automatically deducted during the channel test. Therefore, a cable with a length of 5 m and 10 m can easily pass the test, and a real Jumper test contains the quality of the crystal headers at both ends of the test jumper.

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