Analysis of problems in the selection and implementation of cabling products for SMEs

Unqualified cabling products may cause the following problems:

When the network is disconnected; when the distance from the recent time is a little longer, it cannot be reached more than 100 M); 10 M is normal, M is not normal; the number of workstation is not large, the task is not too busy, and the use of five similar lines, the network speed is surprisingly slow. Next we will summarize some cases that often go wrong due to the above reasons in our daily work. We hope that we can learn from you and you will be able to pay attention to them.

I. cabling companies cut corners

I have also encountered some other examples. For example, the five-class line is 8-core. Generally, the 10Base-T and 100Base-Tx networks only use 1-2 and 3-6 lines, while the 4-5 and 7-8 lines do not need to be used. To save time, many companies only need to connect the 4 cores they need. In most cases, the other four cores are cut off. However, some companies use 4 extra cores to connect another PC in the network, or use the cables as a telephone connection. In fact, in 100Base-Tx Ethernet, this type of usage is not allowed because of the high network frequency and data rate, and the large amount of crosstalk.

In addition, some users do not consider the need for expansion during design. Therefore, when new users are added, the second socket is used. One socket can connect two PCs. In principle, this method is basically feasible. This method requires connecting 1-2/3-6 wires to a PC, and connects the 4-5/7-8 wires to another PC. However, in actual work, many companies adopt the connection methods 1-2/3-6 and 4-5/3-6. Users regard the 3-6 pairs as the direct "shared media detection bus ".

In the 10BaseT network, this error method can barely work. Although this may cause many errors to the data frames in all network traffic, the utilization rate (Traffic) of most existing networks is not high, the 100BaseTX network, which is difficult to detect this exception in the Cabling Process, is sensitive to impedance mismatch and near-end crosstalk. However, after upgrade, this wrong connection method will lead to difficulties in accessing the Internet.

If a counterfeit Class 5 plug (in fact Class 3 plug) is selected unfortunately, class 3 plug in the 10BaseT network will not affect the normal operation of the network, however, after the upgrade, parameters such as the NEXT crosstalk will seriously affect the connection between the workstation and the network and often cause data errors. Without testing, these three types of plug-ins will be lurking for a long time and will not be detected, resulting in many network faults. Therefore, be cautious when purchasing these plug-ins!

In addition, it is common that a high link collision caused by a disconnection error and the speed is slow. We know that the threading standards specify the 568A and 568B formats. The two formats are completely equivalent in principle, and the difference is only that the online order is different. A common cabling error is called "string winding". It is characterized by the natural order of line Order in the order of 1-2, 3-4, 5-6, and 7-8. This will cause the crosstalk at the end to exceed the threshold. In general, the server will not be able to connect to the network at Mbps.

2. Fake Cables

There are more fake twisted pair wires on the market than others' trademarks, and fake wires are also marked as authentic wires. In addition to fake lines, there are many situations where three types of lines are used to pretend to be five-category lines and cat-5e lines. If you purchase at will in the market, it will bring serious damage to the network. I remember a company complained that most of his sites were slower to connect to the Internet than before the system was upgraded. Some sites were interrupted and some were not connected at all.

We used 10 M Ethernet, which is very stable and has excellent performance. After the upgrade, all the above symptoms are changed to M. After investigation, we found that we used three types of online and offline products to mark fake and shoddy products. Users who use these counterfeit products will not encounter Application Problems in the 10 M Ethernet environment. Once upgraded to the M environment, only a few short links can barely be used. After re-wiring, the network works completely normally, but the original system integrator has no idea where to go and cannot claim A claim.

Iii. Gigabit cabling is more serious

The first consideration for implementing Gigabit Ethernet is wiring. First, optical cables must be used for a specific Gigabit connection. For example, optical cables must be used for any vswitch or server connection or any Gigabit connection that exceeds 100 meters, or a connection may be connected through areas with radio interference, crosstalk, attenuation, and other problems. The connection must also use optical cables. In addition, it should be noted that there are too many epoxy resin at the end of the optical cable, poor headers, excessive connectors, cable damage, and excessive bending, will lead to a sharp decline in network transmission through the optical cable, or even cause the transmission to stop. Therefore, we recommend that you use high-quality optical cables and install them correctly during cabling.

In principle, Gigabit Ethernet can be compatible with the five types of cables in use. In addition, most major companies do not encounter any problems when using the original cat-5e in Gigabit Ethernet. However, in actual work, the problem of unqualified wiring still exists. For example, in a company, most PCs have 10/100 M NICs installed, but a 10 m switch is used. What's even more outrageous is that some companies actually use telephone cables to replace category-5 cables. The reason is that telephone cables are cheaper than Category 5 cables.

Some other problems may also cause problems for Gigabit Ethernet. For example, according to the 10/100 M Ethernet standard, the cable cannot exceed 100 m. However, when the length of the cable exceeds the limit, Ethernet or fast Ethernet usually work normally. Therefore, many companies ignore cable length restrictions. But when you run Gigabit Ethernet, this will cause you trouble.

If the wiring is not standard, you will face various headaches. The lessons learned and lessons learned are common mistakes in actual work and are worth learning. I hope that you can learn more about cabling in this article.