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The network cable is one of the things that is given little attention, and maybe there is a misconception that the quality of the network cable does not affect the performance of the network; But the parameters mentioned below for a network cable not only prove the opposite of this position, but also emphasize the importance of the network cable as one of the most important components of the network:
The metal used in alloy network cable pairs is a combination of several metals, among which copper metal plays a significant role in the quality of the network cable, and the higher the amount of this metal, the more reliable the cable is. But in the meantime, the price of copper has caused problems, for example, in the case of types of network cables such as UTP network cables, due to the increase in the price of copper, various factories have started to produce network cables by counterfeiting authentic brands, in which the amount of copper alloy used in the cables In the network cable, it is lower than the standard, and in some Cat5e cables produced in China, pairs 1 and 2 and pairs 3 and 6 are made of copper, and pairs 4 and 5 and pairs 7 and 8 are completely iron.
Therefore, in the fake network cables, pairs 4 and 5 and pairs 7 and 8 are made of iron or less copper alloy is used in them.
As you know, the UTP cables that are used from family 3 onwards mean Cat4, CAT5 and Cat6, have 8 strands or 4 double pairs. Each pair is twisted together, which is the twist of the cables and the size of the twists and the stability of the distance between the two network cables twisted together along the length of the network cable are other important parameters of the cable.
The presence of 8 strands of current-carrying wire next to insulating materials such as wire coating creates a capacitive state in the network cable. In fact, the type of insulators is very effective in the capacitive parameters of the network cable.
Maintaining the centrality of 8 strands along the entire length of the network cable
In some network cables, it can be seen that the insulation on the cable is not at the same distance as the 8 cable strands that are twisted together in pairs, and the 8 cable strands are not always in the center of the outer jacket. This issue also has a significant impact on the quality of the network cable.
In general, if the mentioned parameters are not appropriate, we will have problems such as signal distortion, signal weakening, loss of information, signal return and speed reduction, which makes the information not transmitted correctly. In network science, all the above parameters independently have different names and special criteria, the combination of these parameters will create a series of parameters affecting the copper network cable, the total of which is about 14 parameters.
The question may be raised as to how these parameters can be measured or to find out about their presence or absence in the network cable; in fact; Determining whether the purchased cable is standard is beyond our control and requires special tools and tests, so the only thing that can be done to buy a good network cable is to pay attention to the company that made it, along with making sure that this brand is original; Reputable brands in this category have approvals from international standard centers and institutes that confirm their proper functioning.
Each input signal to the network cable creates resistance in it, which is related to the cross section of the wires. Therefore, if we have different cross-sectional levels along the length of the network cable, we will also have different resistances.
Thus, another point that can be mentioned about the quality of network cable is maintaining the cross-sectional area along the length of the cable. When we pass a signal through a copper network cable, the metal shows its resistance during the passage of current, which changes the cross section along the length of the cable; It will increase or decrease the resistance. If we want to have a uniform cross section, we must first have a uniform cable. Therefore, another thing to be careful about cables is to have a constant cross-sectional area along the entire length of the cable, because this parameter affects the speed of data transmission that is traveling on the network cable. Tension in the network cable is one of the most important reasons for creating cross-sectional areas. Is different .
To prevent such a problem during the cabling process, warn the installers about pulling the network cable.
Installation of network components and cabling is more important than quality
There are many parameters in network installation, some of which are mentioned below.
Excessively untwisting the network cable (meaning pairs of wires): As you know, when an electric signal flows on a cable, it will have an electric induction on the adjacent cable, which in the network cable removes this electric induction by twisting and twisting the cables around each other. Therefore, maintaining twists until the last contact points of cables with connectors and keystones is one of the most important points of network installation and connections. The truth is that the increase in speed and frequency in different cables (meaning Cat3, Cat4, Cat5, Cat5e and Cat6) depends on factors such as the type of network cable and the techniques used in twisting. Therefore, failure to twist the cable to the last points and loosening the pair of wires removes the effect of mutual induction that the cables have on each other, which can have destructive effects on the quality of information transmission and disrupting standards. This is why punching and connecting cables to keystones and connectors is very important.
Removing too much cable during connections: If the insulation (jacket) on the network cable is removed too much from the cable, Again, it will have a destructive effect on the arrival of a healthy signal.
The network cable is pulled
Stretching the network cable during cabling will cause a change in the cross section of the cable, which will cause the problem of signal return.
Gathering the cable in the wrong space: Gathering the extra cables and folding them at the end of the line and putting them inside the duct also causes problems such as weakening the signal and changing the impedance (resistance) of the cable, which will result in a change in the impedance of the signal itself. This issue is very critical when communication is by Cat6 cable and can completely cut the communication.
Pressing the network cable: Pressing the cables in the small duct is also what some installers do, which causes a change in the physical shape of the network cable.
In general, during installation, any factor that causes a change in the physical shape or material properties of the network cable is tolerable to a certain extent (which depends on their margin) But more than that, it will change the parameters of the cable and cause all kinds of problems mentioned.
The amount of security margin that you can change up to the standard size is called margin. For example, consider a glass full of water, there is very little margin because as soon as it is shaken, the water will leave the standard of the glass and water will spill. But a glass that is half full Its margin is half a glass, which means you can shake it a bit without the water leaving the glass standard.
Margins are very different in different classifications such as Cat5, Cat6 and Cat7. For example, in Cat6, the margins are very small, and that is why the installation and operation of the physical network platform in Cat6 is very sensitive.
One of the differences between the cables produced by different companies is in these margins. In a series of them, the margins are attached to the edge of the standard, but some others have a suitable margin, and with a slight change in some parameters, they will still comply with the standard, and there will be no problem, and the cable will easily be damaged by heat or a little stretching, etc. It will be suitable.
One thing to note is that the standard is not the highest level of quality. The standard is the minimum parameters that are required to communicate. Therefore, it is not the case that when we meet the standard, we have the most desirable quality.When a manufacturer meets the standard, it means that he has met the minimum level of quality, but it is not known whether the product of that company has the highest quality or not.
Pay attention to this example:
You have prepared a software CD written on the CD, the minimum space required for its installation is 2 GB. The standard here is 2 GB, but if you have more space, it's better. In other words, if your system has only 2 GB of space, you have only met the standard.
Network cable parameters at different frequencies
Network cable parameters have different values based on different frequencies and these different values are different in different frequencies for different categories. For example, the minimum frequency in Cat5 is 100MHz, but for Cat6, the minimum required frequency is 200MHz, and this frequency reaches 600MHz in Cat7. The higher the frequency, the greater the induced field.
It should be noted that in Cat7, due to the high frequency, more parameters must be calculated and considered. For example, in Cat7, the cross talk of a cable with respect to the adjacent cable should also be calculated. That is, the mutual induction of adjacent cables must be calculated. While in the lower categories, this issue will not have much effect on the installation and will not be calculated.
The higher the speed of the network cable, the more accurate the installation
Installers who used to work on Cat5, for example, due to the addition of parameters in Cat6 or Cat7, may not be able to do the job properly, and the result of cabling should be checked in the final test through valid testers.
Obviously, when working on Cat6 or Cat7 standard, quality is not the only thing that matters. But very minor and vital points are also added to it, which should only be paid attention to during installation and have nothing to do with the quality of the product.
Network installers should know these things, and if they don't know, they should be tested at the time of network delivery. Therefore, when the speed increases, a number of parameters become important, some of which are related to the quality of the network cable and some of which are related to the installation of the network cable and passive network equipment.
The above items are very sensitive and critical that a user or network administrator cannot test, measure and make sure of the health of the work without professional testers. When all the points of the Cat6 standard have been followed during the installation of the passive equipment, and the active equipment has also followed the Cat6 standards, but you cannot use this backbone; Get the Cat6 standards, then there is a problem in the workplace (which can be in terms of product quality or in terms of installation) and naturally only specialized testers can find the problem here.
How to compare the network with the standards?
So far, we have seen how to install, the quality of network equipment, etc. are involved in setting up a network. But we should be able to measure all these parameters with a standard. That is, we have to see whether each of these parameters is correct and whether the combination of these is correct or not. For this, there are a number of standards such as the following standards:
- TIA 568B EIA standard/
The most used standard in Iran is the TIA / EIA 568B standard. There are definitions in the standards that say, for example, that the various parameters that each of the network components have at a certain frequency, for example 200 MHz, must have specific values, which are the standard values that have been specified and announced in advance, and the values related to the network components, such as the network cable, are set by the manufacturer It announces on its website. Now these two values should be compared with the tester.
Thus, the tester; It sends frequencies in the ranges required by the standard, sums up the values and compares them with the standard values, and finally says that the result of the test is Pass or Fail. If the result was Pass, it means that all the parameters worked correctly and met the standard. And if the result of the test is announced by the tester Fail, it will report the reason to us. For example, the network cable is damaged, or the Jack or Plug is damaged, or even the installer did not comply with the technical issues, so after identifying the problem, we can quickly take action and get the necessary results from the network equipment.
As mentioned earlier, to check a physical network platform in terms of different parameters and compare with the standard, advanced devices and testers should be used, and these devices are very expensive. For example, the Fluke DTX-1800 device is used to verify the performance of a network cable and check its parameters. The price of this device is around tens of millions of Tomans.
Due to the importance of working in accordance with the equipment standard, various companies operate in the field of manufacturing all kinds of network equipment testers. One of the most famous of them is Fluke Networks. In the following, we will get to know more about this company and its types of equipment.
Before introducing the tester and dealing with it, we thought it would be better to point out the importance of having a tester when testing a network and pay attention to the fact that, unfortunately, in some network projects that are launched in the country, in case of any problem of any of the people involved in the project They attribute the cause of the problem to another group. Because the goods are procured from one place, the installer is the company or another person, and the consultant is another person, and the employer, who is the owner of the project, is next to them. On the other hand, if the material is not of high quality and has a defect, the seller will not take care of the problem and will put the problem on the installer, then the installer will contact the designer, etc., and unconsciously, a loop will be created that no one will be able to open.
Now, even with a reliable tester and with the analysis it provides, it is very easy to categorize the problems and find the root cause.