4-Network transmission media

I. signal

1 > Information: people's understanding of the way things exist or move in the real world.

2 > data: specific values used to describe some attributes of things

3 > signal: the medium of information transmission

2. Classification of signals

1. Analog signal: continuously changing physical quantity

2. Data signals: discontinuous physical quantities, signal parameters are not continuous, high and low are fixed.

The advantages of digital signal: strong anti-interference ability, long transmission distance, and can guarantee the quality.

Third, twisted pair

1. Twisted pair classification

1 > shielded twisted pair (STP)

The wire is coated with a metal omentum, which is used in an industrial environment with a very complex electromagnetic environment.

2 > unshielded twisted pair (UTP)

2. Standard and classification of twisted pair

CAT 5 category 5 lines are suitable for 100MBPS networks

CAT 5e Super Category 5: less attenuation, less crosstalk, performance better than Category 5

CAT 6 transmission frequency high 200MHZ

CAT 7 500HMZ

Fourth, optical fiber

Single-film fiber: for high speed, long distance, high cost, difficult termination, narrow core wire, need laser source, low dissipation and high efficiency.

Multi-film optical fiber: used for low speed, short distance, low cost, easy termination, wide core wire, good focusing, light source can be laser or diode, high dissipation, resistance effect

5. Ethernet interface

RJ-45 crystal head

Optical fiber interface: FC ST SC LC narrow square optical fiber interface MT-RJ

VI. Information socket

Information module: information socket panel

Specification for the connection of twisted pair

1. Line sequence:

T568A: White green, green, white orange, blue, white blue, orange, white brown, brown

T568B: White orange, orange, white green, blue, white blue, green, white brown, brown

1Pol 2 send 3Pol 6 for acceptance

2. Connection of cables

Standard network cable (straight-through or straight-through): used to connect different devices (Amura Bmerb)

Crossover: for connecting the same device (Amurb)

Reverse line: not used for Ethernet connection, but mainly used for connecting the serial port of a computer to the CONSOLE (control port) of a router or switch. its line sequence is 1-8 at one end and 8-1 at the other end.

Special case: the computer is directly connected to the router.

The switch is connected to the switch, either the straight line or the cross line is OK, generally using the cross line.

VIII. Marking of cables

Cable label

Pipe label