10 cabling problems during LAN Construction

1. How to correctly select the cabling material-Polyvinyl Chloride material PVC) and flame retardant, low smoke, non-toxic material LSFRZH )?

At present, our people pay more and more attention to environmental protection and have higher and higher requirements on the quality of their living environments. However, the basic premise of the quality of life is the safety of survival. Many people have not yet realized the correct choice of materials in the network cabling system, so as to maximize security and reliability when a crisis occurs. A big fire broke out at the deguoduxaar Dufu airport, killing 16 people. More than 60 people were taken to the hospital due to excessive breathing smoke. The accident was caused by the toxic halogen-containing cables arranged in the hall. In existing network engineering, the vast majority of cables contain halide. When they burn, toxic smoke may occur. The harmful substances in the smoke can hurt people's eyes, noses, mouths, and throat, and these smog can also cause serious breathing difficulties. Many victims failed to escape from the fire.

Currently, in terms of materials selection for cabling products, in addition to network application-related performance indicators, a very important performance is the selection of flame retardant, low smoke, halogen-free materials. ISO has the following standards for flame retardant, low smoke and halogen-free materials:

Flame Retardant: the flame retardant standards are IEC 60332-1 and IEC 60332-3C. Compared with flammable materials, the flame retardant speed can be greatly reduced. More importantly, life-saving devices will more easily isolate the flame and greatly reduce the chain risks caused by fire.

Low Smoke: The standard for low smoke is IEC 61034, which produces much less smoke than conventional PVC products, greatly increasing the chance of survival.

Halogen-free: The standard for halogen-free is IEC 60754. Compared with halogen-containing materials, when halogen-free products are in combustion, no corrosive gases, such as chlorine, fluorine, or hydrogen chloride, are generated. In addition to harming the human body, these gases also corrode the device.

A Brief Introduction to the above standards:

IEC 61034 standard, which is a standard for measuring smoke density under certain conditions.

The IEC 60332-1 standard test environment is to test an independent vertical insulation cable. Place a burning air rifle at a 45-degree angle with the cable, and then compress it for one minute. The standard stipulates that the burned insulation cable must be able to be extinguished by itself under this test condition. In addition, the burned cable cannot exceed 50mm from the top-end cable fix.

IEC 60332-3 CAT. C standard, which is used to test a cluster of cables. This is a comprehensive fire test, the entire test is carried out in a 4 m high cabinet. This CAT. C testing requires the help of flammable materials of 1.5L per meter. The burning time is 20 min. This standard stipulates that, under this test condition, the maximum distance allowed for flame extension is 2.5 m above the bottom side of the combustion air rifle.

IEC 60754 standard, which is used to determine the amount of halogen acid gases emitted when the polymer material extracted from the cable is burned.

In short, for safety, it is very important to use flame retardant, low smoke, non-toxic wiring materials. However, the price is about 10% ~ more expensive than ordinary materials ~ 20% price.

2. How can we achieve high-quality cabling?

The cabling project should be based on the relevant national standards, combined with the development direction of international cabling products and relevant international standards, from different perspectives such as product manufacturers, suppliers, system integrators and users, the end users of the Integrated Wiring project are provided with a way to ensure the quality of the project:

1) high-quality products are the prerequisite for ensuring the quality of the project. products that comply with international standards should be selected.

2) Select a strict supply channel to ensure the reliability of the supply and timely supply.

3) selecting system integrators with strong professional technologies and regular operations is the key to ensuring engineering quality.

4) The performance-to-price ratio is an important indicator for measuring the cabling system. You must consider both current requirements and future development needs.

5) All information points should be tested after the cabling project is completed.

6) Integrated Wiring integrators should provide detailed technical documents.

3. Why is network segmentation required?

In Ethernet 10 BASE-5, the physical layer standard specifies a maximum of 5 network segments for a LAN. The maximum number of sites for each CIDR block is 100, and the maximum length of the CIDR block is 500 mb. Therefore, it is sometimes necessary for a department that uses a LAN to divide a single logical LAN into several separate LANs to adjust the load. In addition, sometimes the distance between the two machines is too long, even if the cable laying is not a problem, but because the network information delay is too long, it will affect the normal operation of the network. The solution is to divide a large LAN into several smaller LAN segments ).

Based on the security and reliability of the network, dividing a large network into a smaller network helps to isolate faults and protect the security and confidentiality of each area of the network.

4. Why should we pay attention to comprehensive crosstalk, balance and ripple loss during integrated cabling?

During the test of the Integrated Wiring System, attention should be paid to the problem of comprehensive crosstalk, balance and return loss. Comprehensive crosstalk refers to the sum of crosstalk between individual cables when one or more cables are transmitted simultaneously. Balance refers to the balance between cables and connectors. The balance is similar to the impedance, which is an important parameter for measuring electromagnetic compatibility EMC. Generally, the vertical transformation loss LCL and vertical transfer loss LCTL are used to define the balance. Return Loss SRL) is an important parameter for measuring whether the entire link structure is consistent. It is mainly caused by inconsistent impedance in the link and usually occurs at the joint and outlet. Parameters are very important in high-speed full-duplex networks.

5. I often hear that Category 5 cabling systems support 155 Mbps, but EIA/TIA 568A and ISO11801 only specify the performance of the cables to 100 MHz. Why?

First, you must know the difference between MHz and Mbps. MHz refers to the electronic signal, the unit of frequency, which is usually called bandwidth. Mbps indicates the throughput, which is the transmission rate. For example, the bandwidth is equivalent to the road, and the speed is the car running on the road. Obviously, the higher the broadband and width of the road), the more cars are accommodated on the road, the higher the transmission volume. Similarly, on a specific width Road, the faster the speed, the higher the transmission volume. On 5 types of cables with a bandwidth of MHz, it is possible to transmit information of Mbps (ATM) or even Mbps Gigabit Ethernet.

6. Some cable manufacturers claim that their cable bandwidth has reached 350 MHz. What does this mean for the cabling system?

After the EIA/TIA 568A standard is revised, the bandwidth standard for five types of UTP is set to 100 MHz, and the bandwidth standard for over five types of UTP is set to 100 MHz, and the bandwidth standard for six types of UTP is set to 200 MHz. In the increasingly competitive market, some manufacturers, especially some well-known manufacturers, certainly place their product quality above the standard. This is possible, just like Simon. The use of high-quality cables and connectors in Integrated Wiring can not only meet the current needs, but also leave sufficient room for the development in the next 10 to 20 years. The integrated wiring project is the foundation of the building's "Nervous System" and should ensure that it will not lag behind within 15 to 20 years. Therefore, system integrators should try their best to choose high-quality products, these high-quality products will exceed international standards in terms of performance indicators.

7. What is the minimum distance between the communication cable and the power cable in the horizontal wiring channel?

It is common to encounter electromagnetic interference sources in Integrated Wiring projects. Generally, it can be processed according to the distance specified in Table 1. In principle, we should try our best to stay away from it. When it is really inseparable, we can adopt blocking measures.

Table 1 Distance between Integrated Wiring and electromagnetic interference sources

8. How do I connect to a 10 m network with a long distance?

When connecting a 10 m network that exceeds m to M, there are usually three methods in the project:

1) Use a repeater. Use a thin cable, plus 3 ~ Up to 500 m for the four reconnections. If it is a twisted pair, you can use the HUB) to extend the transmission distance, but up to 180 m.

2) use a rough cable. The connection distance of the crude cable can reach 500 m. Up to five rough cables can be connected through a repeater, and the total length of the network can be up to 2500 MB.

3) use optical cables and media converters. The converter can convert the RJ45 header or AUI port to an optical fiber interface. Multi-Mode Optical Fiber can expand the network transmission distance to 2500 m, and single-mode optical fiber can expand the network transmission distance to 3000 m.

9. What problems do Power Plant Integrated Wiring need to consider?

Power plants are places where electromagnetic interference is serious. Consider carefully when selecting a cabling system. Generally, the following solutions are available.

1) Use a shield Cable System STP ). When using this method, you should note that the entire system must be shielded from the work zone information outlet, connection cable, to the distribution frame and Cabinet between China Telecom, And the shielding layer must ensure the connection of the overall electrical performance, there cannot be a fault; otherwise, the fault will not be blocked. This method is expensive and difficult to construct.

2) The shielded layer is made of metal trays and pipelines, and the unshielded twisted pair wires (UTP) are still used for cables ). This method requires that the entire cable tray system must be connected to the electrical performance, and there must be good grounding measures. This blocking measure is a good solution. It can be shielded without increasing costs.

3) optical cables are used. The optical fiber has strong anti-electromagnetic interference capabilities. However, because the price of optical cables and end-to-end equipment is relatively high, it is usually used for trunk cabling in integrated cabling projects. Fiber to the desktop is just a matter of beauty. Therefore, we recommend that optical cables be used in the trunk where electromagnetic interference is serious. Horizontal trunk lines use metal trays and pipelines for UTP cabling of shielded layers.

10. Can Category 5 cabling systems support precursor Ethernet applications?

Many users are very concerned about the future support of precursor Ethernet applications for category 5 and Category 5 cabling systems.

Mr. Geoff Thompson, IEEE 802.3 Chairman, pointed out that the IEEE 802.3 AB/1000Base-T Working Group will develop a new DSP signal processing technology to transmit 100 m Gigabit applications over five channels.

Mr. Simon, vice president of technology at us Simon, points out that using over five systems can fully support Gigabit Ethernet applications. However, if a category-5 cabling system is used and you want to determine whether it supports Gigabit Ethernet applications, You need to test the cabling system, in particular the additional testing items of the new testing standard, such as: Integrated near-end crosstalk, return loss, equivalent remote crosstalk, comprehensive equivalent remote crosstalk, etc. If the test results meet the requirements of the new test standard, the cabling system can support Gigabit Ethernet applications. We believe that, in fact, this is related to the cable manufacturer selected in the Integrated Wiring project and the construction quality. If a high-level Integrated Wiring integrator organizes engineering construction and uses the cabling products of famous international manufacturers, the five types of cabling systems can support precursor Ethernet. Otherwise, support cannot be guaranteed.

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