Discussion on LAN cabling technology
Wiring is a key factor when designing a network system. With the rapid development of the Internet and the improvement of computer desktop applications, the new wiring technology connected to the desktop has broad prospects and provides unlimited business opportunities for Category 5E and Category 6 cabling.
Integrated wiring technology
1, wiring standards
The LAN specifications described in this document refer to TIA/EIA-568-A (Commercial Building Telecommunications Cabling Standard) and ISO/IEC 11801:1995 (E) standards. The cabling standards include cabling network topology, performance, components, installation practices, and field testing. There are many telecommunication standards related to it, such as ATMForum, CC99vT, CENELEC, IEEEANSI802 and so on.
2, wiring topology
The TIA/EIA-568-A and ISO/IEC11801 cabling standards are based on the same basic cabling system architecture, and their system architecture is strictly and clearly defined in the standards. Cabling systems include cables, patch cords, and connectors for horizontal cabling, trunk wiring within buildings, and trunk wiring for buildings. Structured cabling supports cabling terminations, and plug-in cords are easily connected or cross-connected to the device. In order to get more LAN cabling technology, we need do more ccna exam questions.
3, the wiring distance
In the standard, the wiring distance is strictly regulated (horizontal wiring <90 meters, building trunk <500 meters, campus trunk <1500 meters), and the wiring distance mainly depends on the actual working area (ie, the building floor area). The trunk wiring distance is based on the distance defined by the actual application.
4, wiring performance
In the two standards of TIA/EIA-568-A and ISO/IEC11801, 100-ohm twisted pairs are classified according to their performance:
Category 3: specified as 16MHz;
Category 4: specified as 20MHz;
Category 5/5E: specified as 100MHz;
Category 6: specified as 250MHz.
5, cable electrical transmission performance parameters
DC resistance is unbalanced;
Unbalanced capacitance to the ground;
Structural return loss (SRL);
Near-end crosstalk attenuation (NEXT).
6, connector electrical transmission performance parameters
Near-end crosstalk attenuation.
7, horizontal wiring link performance
The transmission characteristics of the TIA/EIA-568-A standard for horizontal wiring are based on its constituent components, while ISO/IEC 11801 is application dependent. In addition, the ISO/IEC 11801 specification is based on a link (ie, does not include work area cables and equipment cables), while TIA/EIA-568A is based on a channel. The TIA/EIA568-A minimum channel near-end crosstalk attenuation can be derived from the characteristics of the constituent elements (eg, the channel near-end loss is the sum of the phase-to-phase losses of the components it uses), and the maximum attenuation is the attenuation of each component in the channel. Sum. For ISO/IEC 11801 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, the crosstalk attenuation ratio
ACR is associated with a letter-to-string ratio (SCR) defined in LAN technology (usually more precisely defined as crosstalk and insertion loss ratio NIR). ACR is not affected by transceiver changes, as is SCR and NIR.
Since there is no technology supporting 4dBACR above 100MHz, there is no specific application associated with ACR above 100MHz. In addition, with the development of network technology and the elimination of crosstalk methods, the wiring selection will no longer depend on the ACR value (that is, after the ACR is fixed, the attenuation associated with the cable length and the near-end crosstalk can compensate each other).
9, data transmission
Design goals dictate modulation techniques, signal shaping, and the complexity of eliminating crosstalk. The most challenging and attractive are 1000BASE-T based on Category 5E cabling and 100BASE-T2 based on Class 3 cabling. These recommendations require extremely complex compensation for cable defects. For example, 100BASE-T2 requires digital signal processing and mixed-signal processing techniques in two pairs of Class 3 (Class A of ISO/IEC11801) wiring. Moreover, 100BASE-T2 is operated under the environment of near-end crosstalk and only conforms to FCCA or B and CISPR.022A or B.