LAN cabling Technology

LAN cabling Technology

Wiring is a key factor in designing a network system. With the rapid development of the Internet and the improvement of computer desktop applications, the new technology of wiring connected to the desktop has a broad market prospect, and provides unlimited business opportunities for 5E and 6 categories of wiring.

Integrated Wiring Technology

1. Cabling Standards

The LAN technology mentioned in this paper all refer to TIA/EIA-568-A (standard for telecommunication cabling in commercial buildings) and ISO/IEC11801: 1995 (E) Standard. The cabling standard covers the cabling network topology, performance, components, installation practices, and on-site testing. There are many related telecommunications standards, such as ATM Forum, CC99vT, CENELEC, and IEEEANSI802.

2. Wiring Topology

The TIA/EIA-568-A and ISO/IEC11801 cabling standards are based on the same basic cabling system structure, which is strictly and clearly defined in the standards. Cabling systems include cables, plug-in cables, and connectors for horizontal cabling, trunk cabling in buildings, and trunk cabling in buildings. Structured Cabling supports cabling, and it is easy to connect to the device or use a plug-in cable.

3. Wiring distance

In the standard, there are strict rules on the wiring distance (horizontal wiring <90 meters, building trunk <500 meters, Park trunk <1500 meters ), the cabling distance mainly depends on the actual work area (that is, the building floor area ). The trunk cabling distance is based on the actual application distance.

4. Wiring Performance

In the TIA/EIA-568-A and ISO/IEC11801 standards, 100 ohm twisted pair wires are divided according to their performance:

Class 3: defined as 16 MHz;

Class 4: 20 MHz;

Category 5/Category 5E: defined as 100 MHz;

Category 6: 250 MHz.

5. Cable Electrical Transmission Performance Parameters

DC resistance imbalance;

DC resistance;

Working capacitor;

Unbalanced local capacitance;

Characteristic Impedance;

Structure return loss (SRL );

Attenuation;

Downlink attenuation (NEXT ).

6. Electrical Transmission Performance Parameters of connectors

DC resistance;

Return Loss;

Attenuation;

End-to-End crosstalk attenuation.

7. Horizontal cabling link performance

TIA/EIA-568-A standards the transmission characteristics of horizontal cabling are based on its components, while ISO/IEC11801 relies on applications. In addition, ISO/IEC11801 specifications are based on links (I .e., do not include work zone cables and equipment cables), while TIA/EIA-568A is based on channels ). TIA/EIA568-A minimum channel near-end crosstalk attenuation can be derived from the characteristics of the components (for example, the channel's near-end loss is the sum of the phase loss of the components used ), the maximum attenuation is the sum of the attenuation of each component in the channel. For ISO/IEC11801 links, the minimum near-end attenuation and maximum attenuation are based on the standard applications listed in appendix G. ISO links are classified by performance (Class A to Class E), where class E is equivalent to Class 6 performance.

8. crosstalk attenuation Ratio

ACR is associated with the string-to-string ratio (SCR) defined in the LAN technology (typically more precisely defined as the crosstalk-to-insertion loss ratio (NIR ). ACR is not affected by changes in the transceiver, as are SCR and NIR.

Because there is no technology that supports 4 dbacr above MHz, there is no specific application associated with ACR above MHz. In addition, with the development of network technology and the emergence of crosstalk elimination methods, wiring selection will no longer depend on the ACR value (that is, after the ACR value is fixed, attenuation related to the cable length and mutual compensation between the near-end crosstalk ).

9.100 ohm wiring performance Field Test

The transmission performance of the cabling system depends on the performance of its components and the installation process. The TIA/EIA technical system announcement (TSB-67) specifies the parameters of the 100 ohm twisted pair cabling tool for testing performance after installation.

10. TIA/EIA-TSB-67 test parameters

Connection diagram: Check the connection between the connector and the plug of the cable to identify the connection error.

Attenuation: signal loss in a channel or link.

Length: Maximum wiring length.

Near-string attenuation: signal coupling between adjacent transmission and receiving lines.

11. Comparison of MHz and MBps

The attenuation and NEXT of cables can be obtained from the scanning measurement, and the specified test range is from 100 MHz to MHz. The attenuation and NEXT values indicate the sine voltage loss at a specific frequency and cannot be confused with the bandwidth limit value, bit rate, or port (that is, 622MBps does not mean that the wiring is limited to 622 MHz ). According to the design objectives, modulation and signal processing accompanied by amplitude, frequency, or phase changes are usually used to change the desired bit rate to the acceptable signal sending rate (Porter ).

12. Data Transmission

The design goal determines the modulation technology, signal shaping, and the complexity of eliminating crosstalk. The most challenging and attractive is the 1000BASE-T Based on 5E type cabling and 100BASE-T2 based on 3 types of cabling. These recommendations require extremely complex compensation for cable defects. For example, 100BASE-T2 requires digital signal processing and hybrid signal processing on two to three types of cables (ISO/IEC11801 Class. In addition, 100BASE-T2 is applicable to FCCA Class, Class B class, And cispr120022a class or Class B class in environments with poor near-end crosstalk.

13. crosstalk Environment

Because multi-wire pair cables can be used in multiple applications, applications based on parallel data transmission and multimedia technologies have been implemented (for example, 1000BASE-T uses 4-wire pairs for simultaneous data transmission ), therefore, other sources of crosstalk and their own near-end crosstalk must be paid attention to, and new performance parameters, such as RSL (return loss), are also added for 5E and 6 types of cabling) and ELFEXT (equivalent remote crosstalk ).

The near-end crosstalk (NEXT) or remote crosstalk (FEXT) coupling referred to by external crosstalk cannot be eliminated in the same way as the near-end crosstalk (that is, the crosstalk comes from external connections ). When crosstalk is related to two possible sources of external interference, it is defined as multi-source NEXT (MDNEXT) and multi-source ELFEXT (MDELFEXT ).

The remote crosstalk (FEXT) describes the crosstalk coupling between the transmitter (source) at one end of the cable to the loop at the other end.

The equivalent remote crosstalk (ELFEXT) describes the crosstalk coupling between the transmitter (source) at one end of the cable and the loop at the other end, which is obtained from the FEXT (Remote crosstalk) minus the attenuation of the line, this eliminates the impact of cable length.

The Return Loss (RSL) is determined by the matching degree of each element in the transmission channel. For 1000BASE-T, only matching connections can meet the demanding RSL requirements.

14. Shared and switched LAN

In a LAN, a workstation can use a Media Access Control Protocol (MAC) to share a single channel or connect to a vswitch. In a shared LAN, workstation is connected to a repeater or concentrator to form a broadcast channel between sites. Therefore, the workstation can receive information sent from any station. The workstation runs in half duplex mode. At the same time, only one message can be sent on the LAN, which is determined by the MAC protocol.

The workstation mentioned above can also be connected to a vswitch. Each switch allows only one activation source at any single time. The switch copies the information packet from an input port to a specific output port, and other ports can send and receive different information packets. When the working end is directly connected to the vswitch, it is in full duplex mode, so there is no need for access control.

15. transmission delay and delay Distortion

In the shared 1000BASE-TLAN model, the round-trip delay that includes the wiring transmission delay is a key parameter. In addition, for applications that use synchronous transmitters such as 100BASE-T4 (Half Duplex) and 1000BASE-T (Full Duplex), latency distortion (that is, the difference between line-to-line transmission latency) is also important.

Under any conditions, the difference in transmission latency or latency between the fastest and slowest single link must be greater than 50ns (the frequency range is 2 MHz to 100 MHz ), the travel delay cannot exceed ns. As a further functional requirement, once the 1000BASE-T is installed, the latency distortion between the cable pairs caused by environmental conditions will not exceed ± 10ns when the above requirements are met.

High-speed technical cabling Topology

1.1000/BASE-T cabling Topology

1000BASE-T, 100BASE-T, and 10BASE-T have different topologies. Due to timing restrictions, there are only one active relay in the 1000BASE-T conflict domain, and the 100BASE-T cannot exceed two. The number of 1024 sites limited by MAC remains unchanged. It supports three types of media: Category 5, category 5E, and category 6 twisted pair wires. The multimode optical fiber can be satisfied by combining FDDI and PMD specifications, and the 1000/100 BASE-T can also support Multimode Optical Fiber. However, due to the timing limitations mentioned above, the two-kilometer distance supported by PMD cannot be achieved.

2. ATM cabling Topology

The 155Mbps ATM supports 5/5E/6 categories, 150 ohm STP, multimode optical fiber (UNI3.1) and single-mode optical fiber applications. It is predicted that the cat6 cabling system will support the 622Mbps and 1.2Gbps ATM applications. The ATM topology is a switching network. That is to say, a work site uses an independent switch with multiple routing functions to connect to another switch on the Internet. Because the MAC protocol of the ATM does not set a time limit for end-to-end extension, the ATM provides a virtual and unlimited end-to-end extension.

3. VG-AnyLAN Topology

VG-AnyLAN is also known as 100VG-AnyLAN and the demand-first network. It is a 802.3 Mbps protocol developed by the 802.5 Working Group and supports the or frame format. However, the Protocol itself is different from other protocols, because the network can only run in one frame format, VG-AnyLAN can run in a frame format of 802.3 or 802.5, rather than both.

VG-AnyLan supports Class 3, Class 5, class 5E, Class 6 UTP, and 150 ohm shielded twisted pair wires (STP ), it also supports 2 km from 1300nm wavelength and 05 km from 800nm wavelength optical fiber link. Its topological structure consists of a chain Hub, similar to a 10BASE-T structure. The end-to-end distance limit is related to the source repeater type.

Summary

High-speed LAN technology is developing at a rapid speed. 100 ohm unshielded twisted pair cabling will play an important role due to its large market share. Category 6 Cabling is also recognized by the industry because it provides a large amount of free space (additional margin for wiring performance) to support low-cost network devices. It is foreseeable that the Gigabit Ethernet standard will support 6 categories of cabling in a more comprehensive manner while supporting installed, existing, and 5E cabling.