Design and test of gigabit network integrated wiring system

Gigabit Network is a fast Ethernet, its data transmission rate of 1Gbps, still using CSMA/CD access control mechanism and with the existing Ethernet compatibility, with the support of cabling system, can make the original Fast Ethernet smooth upgrade and can fully protect the user's original investment. At present, gigabit network technology has become a new network and transformation of the preferred technology, thus the integrated cabling system performance requirements are also improved.
　　
1, gigabit network cabling standards
　　
The standard for Gigabit Ethernet is set by IEEE 802.3, which currently has 802.3z and 802.3AB two cabling standards. 802.3AB is based on twisted pair wiring standards, using 4 to 5 type UTP, the maximum transmission distance of 100m. And the 802.3z is based on Fibre Channel standards, using three kinds of media:
　　
A) 1000BASE-LX specification: This specification is for long-distance use of multimode and Single-mode fiber parameters. Multimode fiber transmission distance of 300 (550 meters, Single-mode fiber transmission distance of 3000 meters. The specification requires the use of relatively expensive long wavelength laser transceivers.
　　
b 1000BASE-SX Specification: The specification is used for short distance multimode fiber parameters, using multimode fiber and Low-cost short-wave CD (compact disc) or Vcsel laser, with a transmission distance of 300 (550 meters).
　　
c) 1000BASE-CX specification: The use of short distance shielded twisted-pair STP, its transmission distance of 25m, mainly used in wiring between the use of short jumper cable to high-performance servers and high-speed peripherals connected.
　　
2, Gigabit network integrated wiring system cable selection
　　
The integrated wiring system consists of three wiring subsystems, the wiring subsystem of the building, the backbone wiring subsystem, the horizontal wiring subsystem (including the work area cable). Gigabit Network integrated wiring system, in addition to the general Fast Ethernet integrated wiring system design features, more important is to reasonably choose UTP, cable and connectors. (Computer science)
　　
2.1 Choice of optical cable
　　
Optical fiber cable is mainly used in complex wiring subsystem, the interference requirement is high or the building backbone distance exceeds 100m also uses the optical cable as the building backbone wiring subsystem. Select the cable should be based on the actual distance and combined with 802.3z specifications. Take into account economic issues in the context of meeting technical requirements.
　　
2.2 Selection of twisted-pair wires
　　
Twisted pair is the largest proportion of the three integrated cabling subsystems, and its use determines the performance of the integrated wiring system to a large extent, and must be selected rationally.
　　
It is known from Shannon's theorem that the relationship between channel bandwidth and channel capacity is:
　　
C=WLOG2 (1+s/n) (bps) ................ (1)
　　
C is the channel capacity, W is the channel width, n is the noise power, S is the signal power, and the s/n represents the signal-to-noise ratio.
　　
From (1) We can improve the channel capacity by improving the channel bandwidth and signal-to-noise ratio. Currently available for high-speed network applications, the twisted pair has 5 classes, 5 classes, and 6 classes, with a maximum bandwidth of 100MHZ, 100MHZ and 200MHZ respectively. Because of the Gigabit network UTP wiring Standard 802.3AB is based on the use of 4 pairs of 5-type, and 5-type UTP Bandwidth range of 1 (100MHZ. Therefore, only from the bandwidth point of view, the selection of the 5-type twisted pair can meet the requirements of gigabit network applications.
　　
Then consider from the angle of signal-to-noise ratio. Gigabit networks need to simultaneously use UTP four pairs of cables for high-speed parallel data transmission, signal and noise, respectively, the following characteristics of the cable parameters, these parameters are:
　　
Attenuation (attenuation): a weakening of the transmission of a signal along a link.
　　
echo loss (RL): reflect the power of the transmit signal due to the impedance of the cable and the impedance of the link connector deviating from the standard value.
　　
Near-end crosstalk loss (NEXT): Similar to Noise, is an interference signal uploaded over a pair of adjacent lines. This crosstalk signal is caused by the proximity of a UTP to a capacitor or inductance.
　　
Adjacent line to composite crosstalk (power sum): refers to the total number of crosstalk between the other three pairs of lines in the same environment where the data is transmitted simultaneously using a UTP four pair. Set the sending signal to T, the above four characteristic parameters are indicated by a, R, NE and P respectively:
　　
Singal (f) =f1 (T, A) ............ (2)
　　
Noise (f) =f2 (R, NE, P) ......... (3)
　　
The formula (2) and (3) respectively represent the receiving signal and the noise, and the parameters A, R, NE and P are all functions of frequency F in the two-type. The following two formulas are obtained for the calculation of signal-to-noise ratios:
　　
It is known from these two formulas that to improve the signal-to-noise ratio, we should choose the good UTP of A, R, N and P to improve s and reduce N. The higher the type of UTP, the more the above parameters are from the limit of the standard, the better the performance. Because some of the parameters of the 5 UTP are affected by the quality of construction or the environment, often do not reach the requirements of wiring standards, the Super 5-type UTP improved the above defects of 5 types of UTP. Therefore, the Ultra five class and the six type UTP can satisfy the signal noise request. Because of the performance of six types of UTP in the Super Five category, and six types of UTP can also meet the future high-speed network applications, therefore, in the current situation should be preferred six types of UTP and its supporting connectors, Plug-ins.