The basic transmission unit of the tcp/ip physical layer is bit. Bit is a unit of information, transliterated from English BIT. It is also a bit in a binary number, a measurement unit of information, and the smallest unit of information.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
The basic unit of the TCP/IP protocol can be said to be a data packet. Because the main job of the TCP/IP protocol is to transmit data and determine that the data has been delivered and received, the next layer to which the data is processed after being processed by the TCP/IP protocol is the network layer, and the data unit of the network layer is data. Packet, so it can be determined that the basic unit of the TCP/IP protocol is the data packet.
The unit of the network layer is a packet; the data link layer is a frame; and the physical layer is a bit.
Bit, a computer term, is a unit of information, which is transliterated from the English BIT. It is also a bit in a binary number, a measurement unit of information, and the smallest unit of information. Information necessary to reduce the number of stimulus alternatives by half in situations where a different choice is required. That is, the information amount (number of bits) of the signal is equal to the logarithm of the signal stimulus amount with base 2. L. Hartley believed in 1928 that logarithmic units are most appropriate to measure the amount of information.
The physical layer is mainly the physical transmission media and signals. The mainstream signals include analog signals and digital signals. The transmission media mainly include twisted pairs and optical fibers.
Analog signal: A constantly changing physical quantity with weak anti-interference and attenuation. It is mainly used in telephone networks.
Digital signal: two constant physical quantities, which are resistant to interference and signal attenuation. They are suitable for computer networks and are currently the mainstream signals.
Twisted pair: Classified by function: shielded and unshielded
Classified by speed: Category 5 100M line, Category 5E 100M line, the transmission speed is faster than Category 5 line Several times, Category 6 Gigabit Line
is divided by interface: Standard 568A: green and white, green, orange and white, blue, blue and white, orange, brown and white, brown; Standard 568B: orange and white, orange, Green white, blue, blue white, green, brown white, brown.
Optical fibers are divided into: single-mode and multi-mode, thick core and thin core, low speed and high speed, short and long transmission distance, cheap and expensive, connectors: FC, LC, ST
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