Release date : 2022/1/23 11:01:00

When it comes to how to choose an integrated wiring system, there are two concepts to be distinguished first, that is, bandwidth (measured in MHz) and data transfer rate (measured in Mbps). It is difficult to make the right choice without distinguishing between these two concepts. For the definition and specific meaning of the two, please refer to the relevant technical articles. It should be pointed out here that there is a relationship between the two. This relationship is related to technologies such as encoding methods, but it is not necessarily a one-to-one relationship. For example, ATM155, in which 155 refers to the data transmission rate, that is, 155Mbps, and the actual bandwidth is only 80MHz; another example is 1000Mbps Ethernet, because of the 4-pair full-duplex working mode, the transmission bandwidth requirement is only 100MHz. In the computer networking industry, data transfer rates are widely used, and in the cable industry, bandwidth is used, so don't confuse the two.

1. Category 5e cable system (Enhanced Cat 5)

It is a system that appears after improving part of the performance of the existing UTP Category 5 twisted pair. Many performance parameters, such as near-end crosstalk (NEXT), attenuation crosstalk ratio (ACR), etc. have been improved. The transmission bandwidth is still 100MHz.

2. Category 6 cable system (Cat 6)

It is a new level of cable system, in addition to the greatly improved parameters, its bandwidth will be extended to 200MHz or higher. Regardless of whether it is a Category 5e or Category 6 cable system, the connection method is still compatible with the widely used RJ45 patch module.

3.7 Category Cable System

Category 7 cable system is a cable standard proposed by Europe, and its planned bandwidth is 600MHz, but the structure of its connection module is completely incompatible with the current RJ45 form. It is a shielding system.

The current progress in the formulation of standards for these three cable systems is as follows: the standards for Category 5e systems are expected to be formulated between November and December this year, and the standards for Category 6 systems are planned to be formulated by the end of 2000. A standard for such systems, which is being studied and discussed in Europe, is not on the agenda of the Standardization Committee in the United States.

The current network technology demand for transmission media

Cabling systems are installed to meet the needs of network applications. What are the current system requirements for network speed? At present, the main computer networks are 4M and 16M Token Ring, 10M Ethernet, 100M Ethernet (including 100BASE-T and 100BASE-T4) and ATM155 (based on twisted pair). These networks can be used in the current Category 5 twisted pair run online.

The only currently unspecified standard is 1000Mbps Ethernet, i.e. what medium it needs to run on is unclear. At present, the final standard of Gigabit Ethernet has not yet been completed, but some basic indicators have been determined. And the bandwidth is within 100MHz.

According to the above basic requirements, users will naturally care: Since the bandwidth of Gigabit Ethernet is still within 100MHz, can it run on Category 5 twisted pair? Judging from the current draft standard, since Gigabit Ethernet runs on 4 pairs of lines in full duplex, although its bandwidth is still 100MHz, it puts forward new requirements for some other performances of the cable system, such as when transmitting Delay (Propagation delay), time delay difference (delay skew) and far-end crosstalk (FEXT) and so on. The most important of these parameters is equivalent far-end crosstalk (ELFEXT), which has the greatest impact on whether or not Gigabit Ethernet works well. When it comes to the user's concern about whether the Category 5 cable system can run Gigabit Ethernet, I think that as long as the Category 5 UTP system can meet the new standards formulated at the end of this year and meet the most important ELFEXT indicators, then it can run Gigabit Ethernet.

What standard will be introduced at the end of this year? One of the standards is to revise the existing Category 5 twisted pair standard (TSB67), adding some new parameters, such as transmission delay, delay difference, far-end crosstalk and so on. If a Category 5 twisted pair cable system is measured against this standard and passes the test, then the system is capable of running Gigabit Ethernet. Another standard is the standard of Category 5, namely Cat5E, which is more stringent than the indicators of Category 5 system standard. If the installed Category 5e cabling system passes the certification tests, then you can be sure there is no problem running Gigabit Ethernet over that system. The standard of Category 6 cable system will be completed before the end of 2000, and the standard is still under discussion; but one thing is certain, that is, its bandwidth will definitely be extended to 200MHz or higher.

Choices faced by users

Faced with these different cable systems, how should users choose? A better way is to start from practical application, consider the room for future development and investment costs, and ensure the quality of installation. From the actual point of view, it means to consider how high the user's requirements for network applications are, how long 10M Ethernet can support the user's application requirements, and whether 100M Ethernet is sufficient. Because the cabling system of the network is a one-time long-term investment, considering future development means considering whether the application of the network will have a demand for a high-speed network such as Gigabit Ethernet or a higher-speed network in the future in a period of time.

It is difficult to make the right decision, especially if it is not possible until years or decades later. The decision to install a Category 3 system can be considered correct if a company installs a Category 3 system that meets the company's network requirements within 10 years; If it is found that it cannot meet the application of the network and needs to be updated, then the decision to install the Type 3 system is questionable. Conversely, if a very advanced cabling system is installed and the application of the network in 10 years is still based on 10M or 100M Ethernet, the investment in the cabling system may be too large, because the cabling system after 10 years may be Another look.

The last is how to ensure the quality of the installation. In addition to the quality of the wiring system itself (usually guaranteed by the manufacturer, and usually not the main cause of the problem), whether it is a Category 3, Category 5, Category 5e or Category 6 cable system, it must be completed through construction and installation, and The construction process has a great influence on the performance of the cable system. Even if a high-performance cable system is selected, such as Category 5e or Category 6, if the construction quality is rough, its performance may not meet the Category 5 index. Therefore, no matter what level of cable system you choose to install, the final result must achieve the corresponding performance, that is to say, the installed cable system needs to be certified to relevant standards to ensure the reliability of the investment. The current situation is that the Category 5 twisted pair system has certification standards to follow, while the Category 5 super system will have a standard at the end of this year, and the standard of the Category 6 system needs to wait.

It should be noted that the standards for Category 5e and Category 6 systems are still under discussion and formulation, so when purchasing these types of systems, choose products from reputable and powerful companies, and have written performance guarantees , thus protecting the investment of cabling users.