Brief introduction of shielding and non-shielding system for network wiring

Today, the integrated wiring system market, there are many domestic and foreign brands, copper cable has super five categories, six categories and seven categories of points, as well as shielding and unshielded points. For copper six categories, seven categories, we will know that the larger the number, the better the performance of cable, and shielding cable and unshielded controversy, in the industry has been a long-standing. Faced with the increasing attention of users to network security, shielding system has developed to today, has been more and more users to accept and adopt, and increasingly highlight its vitality. For the development of integrated wiring system market, how to provide customers with better comprehensive system solutions, has been more people in the industry attention and attention.

As an integrated wiring system manufacturer, Corning provides the end to end products of shielded and unshielded wiring system, for the use of shielding or not shielding, the entire integrated wiring market development, Corning as a wiring market leader, also put forward their own views.

In retrospect, in the late 80, 15 years after the Invention of Ethernet (1974) (1989), a structured cabling system was created, and the topology of the wiring was rapidly "structured". Now, in another 15 years, 2005, we may again experience a great change in wiring systems, and perhaps we are on the verge of another upheaval in web design. Looking ahead, in 2006, about 15% of the active device ports will be 10G ports. The development of wiring system will be more rapid, it is expected that more than 30% cabling installation will become an enhanced six-type cabling system over 2006 years. In addition, around 10% of the world's wiring is upgraded every year. In the foreseeable future years, 10G gigabit Network or 7 types of systems will become the mainstream of the market. ---http://bianceng.cn (computer science)

We know that the existing six and five types of systems can be used for 10G Gigabit Ethernet or 7-class network transmissions. At present, the customer demand for transmission rate makes 10G Gigabit Ethernet network is quietly into our lives, but also slowly popular, as the original Super 5 systems are very popular. According to statistics, the 2005 class six system has occupied more than 60% of the wiring market share. But the fact is that all of the six types of systems that have been installed can only do the same thing as a super five system, that is, the Ethernet network that transmits the largest 1Gb, gigabit bandwidth, cannot be larger. The type of the 7-type system (the draft international standard defines a bandwidth of 1000Mhz) is not available for all devices at present, connect the device's data jumper or have one end is RJ45 type, and such jumper is not up to 7 class performance, the investment of the 7 classes of systems and 6 classes without distinction, become no practical significance. This is why 10G Gigabit Ethernet network can be popular reason.

At present, both the unshielded system and the shielding system, there are 10G solutions, and the new 10G UTP solution with the previous UTP system is very different, because they are imitating the design of the shielding system. Now, the manufacturers of unshielded solutions are also following the Shield system manufacturers vigorously promote the 10G million trillion system, which means that the unshielded system and shielding system once again as a 10G million trillion solution, although it is not a guarantee of future network applications the best choice.

Why is the UTP system not the best choice for future Web applications?

The Shannon theorem, which is well known, the description is as follows: There are obvious differences between the shielding system and the unshielded system, while the shielding system is flat in the 500MHz bandwidth, and the shield systems are still rising; the difference in transmission capacity is about 100% (in 500MHz bandwidth); the higher the frequency, the more easily the problem of data transmission.

At present, ISO/IEC is developing international standards on electromagnetic compatibility. About coaxial cable and its network we already have the relevant standards, and similarly, we can expect that the data network will have similar rules (class E1). The expected result will be that only the shielding system can meet international standards and be used.

Through the actual test of data transmission, it can be seen that the parameters of Ps Fext, based on different electrical transmission characteristics, different cable classes have essential differences. Considering the limit of the theory (Shannon theorem), shielding cable (F/UTP and S/FTP) of the PS Fext index similar, and UTP test parameters are much worse.

But these are not real problems that run at higher frequencies (> MHz). The real problem is that the adjacent line is on the crosstalk.

At the beginning of 2005, the solution for Afext interference was still not found around the 10G million-gigabit transmission problem of UTP in a short 55 m situation. When a high-power signal enters a shorter cable, the cable at the other end will cause serious interference to the adjacent or lashing cables. Obviously, this effect is not compensated. In the aspect of transmission characteristics, there is an essential difference between the shielding system and the non shielding system in the form of twisted pair. The most critical factor for successful transmission of gigabit networks is overcoming the "adjacent line to Crosstalk (alien crosstalk)". This crosstalk is not the crosstalk between different lines in the cable, but the interference signal from the external cable, the external interference signal can come from adjacent cable, or active equipment. Compared with the cable internal crosstalk, this crosstalk cannot be offset by adjusting the active device parameters because it is related to the different conditions of the installation and is simply unpredictable. The only option to reduce this crosstalk is to improve the design of the cable.

When designing the cable for the unshielded system, the adjacent line has become the focus of the crosstalk. Based on a simple fact: the increase of distance between cores will weaken crosstalk, resulting in many different schemes. Different manufacturers have adopted different improvement schemes. However, the improvement of all UTP can not fundamentally solve the adjacent line crosstalk problem. And the shielding system is not bothered by these problems at all.

Advantages of Shielded Cable

The advantages of using shielding system can be proved by different complex parameters, such as coupling attenuation, shielding efficiency and transfer impedance. But from a user's point of view, perhaps the most significant is a shielded cable based cabling solution in the ever-increasing high-speed network application of the real advantage of the world.

Today, more and more network applications need shielding cable and shielding cabling solutions. In fact, network equipment manufacturers have installed shielding connectors, so that network equipment without the use of very complex and sensitive digital signal processing DSP technology, under the premise of avoiding electromagnetic radiation and improve the ability to resist interference. Even those network devices that have designed filters and enhanced circuits in the circuit can still benefit from a shielded wiring system. The EMI obtained from the surrounding environment must be filtered, dissipated and compensated in the instrument. The smaller the external noise impact, the less the required DSP equipment will be cheaper.

But why does electromagnetic noise or interference continue to affect our network? EMI is a random noise generated by the influence of electric fields and magnetic fields. Electronic devices, such as fluorescent lights, power lines, radios, televisions and mobile phones and computers, can generate electromagnetic interference. When too much electromagnetic interference or noise is obtained by the signal being transmitted, the receiving end may think that the data is incorrect. When the client receives incorrect data, the NIC in the device finds an error and requires the sender to resend it. This reduces the total amount of data transferred by the network because it wastes valuable time by sending and resending the same data. The aggravation of these transformations will affect the efficiency of the network operation.

Proponents of UTP cables firmly believe that electromagnetic noise can be offset by cable balance (twisted pair). This means EMI is first received by a UTP cable, which is then offset. Until now, just a simple balance and filtration at work. However, a new generation of high-speed network applications is under development, and the consequent emergence of environmental pollution. Rising rates need to be driven by new technologies that extend the bandwidth, which can be affected by more EMI sources and create new problems. Moreover, the increase in the number of automated devices on the desk has led to more high-frequency electromagnetic fields to pollute the environment.

When EMI is simply a part of the impact of the use of the network users, as a source of information, may be to some criminal activities to provide opportunities. Therefore, many government agencies, military or financial institutions installed wiring system for security reasons, must carry out the necessary protection. To prevent some important phone calls from being tapped, or to obstruct the security system, use a shielded cable for wiring.

Supporters of UTP cables will continue to maintain their solutions in areas where the electromagnetic environment is worse. In fact, a perfectly balanced cable does have the ability to resist EMI. However, the ideal balance is impossible. Do you know what happens when the "perfect" pair is installed? In fact it is impossible to keep the perfect twisted pair-that is, the balance is broken. You can expect your cables to not bend during installation, or you can use shielded cables as a necessary protection.

In addition, because the core-line twisted-pair length can not be infinitely reduced, so the balance of the twisted pair and filtration effect can only reach 30-40mhz. These high-speed network applications, Gigabit ethernet,622mbps ATM and 2.5Gbps ATM, require sophisticated coding methods and running high frequency segments above 100MHz, all of which will result in more signal weakening due to EMI. Therefore, shielding cable provided by the protection of the network to ensure the operational performance of more practical significance.

In addition, the balance characteristics of UTP cables are not only determined by the quality of the parts themselves (such as the twisted pair) but are affected by the surrounding environment. This means that if the cable is not "detached" enough or is independent of the environment, the balance feature may be compromised. Under the ideal condition, the signal generated by the network device is completely symmetrical, but it will be destroyed by unbalanced transmission channel such as cable. This means that the impedance of the grounding line on the entire link must remain constant. It is also required that no metal object be present near the unshielded cabling system, because any piece of metal around the cable can disrupt the balance characteristics of the UTP cable and thus affect EMC performance. In fact, the cable we install is usually put into a metal conduit, a plastic conduit, or other protection with a different grounding impedance. So, there is only one solution to achieve long-lasting ground performance: All cores are grounded with an extra layer of aluminum foil. Aluminum foil provides protection for fragile twisted-pair cores while creating a balanced environment for UTP cables. This means that shielding solutions based on shielded cables are independent of the environment and are not environment-neutral.

Shielding Cable Manufacturing is quite professional, but because the shielding wiring system design has been fully considered EMI problem, so the installation of shielded cable is quite easy. Shielding wiring system installation does not need to be as strict as the unshielded system. For example, the minimum distance required is 3 times times the minimum allowable distance between the UTP cable and the power line.

Shielding cable compared to the advantages of UTP cable is that it is aimed at the wide use of electronic equipment caused by the impact of EMI. Moreover, the increase in network application rate means that the network is more sensitive to EMI.

Summarize

We can predict that all of us will be able to transition either early or late to Wan Zhaoyi or 7-class cabling systems, regardless of whether he originally installed a five class system or a six class system. The new solution will inevitably prevail: not an enhanced six-type mega-system, or a seven-class system. At present, the shielding solution is at the same starting line as the UTP System solution, and the STP system seems to have more advantages. Although the solution of UTP (unshielded twisted pair) is now very popular, the performance advantage of STP (aluminum foil shielded twisted pair) becomes more and more obvious with the change of time and network application. Through the above discussion, it can be concluded that the shielding system is more suitable for the future development trend of technology.