The commonly used LAN transmission technologies are to give any three .

The commonly used transmission media in LAN are twisted pair and coaxial cable.

and optical fibers, etc.

1. Twisted pair.

Twisted pair wire is a kind of cable that is made of two wires that are coated with plastic insulation material and contain copper cables, which are insulated from each other and twisted into a spiral.

Twisted pair reduces signal attenuation during transmission, reduces crosstalk and noise, and improves immunity to external electromagnetic interference. It was created by Alexander Graham Bell.

Invented. For more than 100 years, it has been used for ** nets.

2. Coaxial cable.

Coaxial cable is a kind of wire and signal transmission line, which is generally made of four layers of materials: the innermost is a conductive copper wire, and the outside of the wire is surrounded by a layer of plastic and insulator.

There is a thin layer of mesh conductor on the outside, and then the outermost layer of insulating material on the outside of the conductor is used as the outer skin. Depending on the size, coaxial cables are available in different standard sizes, ranging from 1 8 inches to 9 inches in diameter.

3. Optical fiber cable.

Optical fiber cable is referred to as optical fiber cable or optical cable. With the increasing demand for data transmission speeds, the use of fiber optic cables is becoming more and more common. For computer networks, fiber optic cables offer incomparable advantages.

The fiber optic cable consists of a fiber core. cladding and sheath layers. The core is made of glass or plastic, the cladding is made of glass, and the sheath is made of plastic.

LAN: ATM, Ethernet, WLAN

WAN: Frame Relay, VPN, ISDN

LAN transmission.

Token Ring. wlan.Bluetooth LAN.

WAN transmission.

tunnel technology. Point-to-point protocol over PPPoE Ethernet. x25 (for banking use).

Coaxial cables, twisted pairs, fiber optic cables and radiating media used in wireless networks.

Twisted pair is currently the most common transmission medium and is divided into two categories: shielded twisted pair (STP) and unshielded twisted pair (UTP). Shielded twisted pair:

It has a metal armor sleeve, which has strong resistance to electromagnetic interference, and is suitable for high-speed network protocol applications with large network traffic. Unshielded twisted pair: The cable sheath is used as a shielding layer, which is suitable for occasions where the network traffic is not large.

The commonly used transmission media for computer networks include twisted pair, coaxial cable, and optical fiber.

The network transmission medium is the physical path between the sender and the receiver in the network, which has a certain impact on the data communication of the network. Commonly used transmission media are divided into two categories: wired transmission medium and wireless transmission medium; Different transmission media have different characteristics.

Network transmission medium refers to the carrier of information transmission in the network, and the commonly used transmission medium is divided into two categories: wired transmission medium and wireless transmission medium.

Wired transmission medium refers to the physical connection part realized between two communication equipment, which can transmit signals from one party to the other, and the wired transmission medium mainly includes twisted pair, coaxial cable and optical fiber. Twisted pair and coaxial cables transmit electrical signals, and optical fibers transmit optical signals.

The wireless transmission medium refers to the space around us. We can use radio waves to propagate through space to achieve a variety of wireless communications. Electromagnetic waves transmitted in space can be divided into radio waves, microwaves, infrared rays, lasers, etc., according to the frequency spectrum, and the information is loaded on the electromagnetic waves for transmission.

The answer is ABC, coaxial cable is also a commonly used transmission medium, cable modem is used coaxial cable (the cable of CCTV is coaxial cable, there is no closed circuit in professional terms).

Answer] The transmission media mainly used in :d LAN are twisted pair, coaxial cable and optical fiber.

Answer]: BWIFI is a technology that can wirelessly connect terminals such as personal computers, handheld devices (such as companion PDA, mobile phones) and other terminals. Therefore, the answer is 8.

According to the network transmission mode, computer networks can be divided into point-to-point networks and broadcast networks. Computer networks can be classified according to the geographical scope covered, and can be divided into local area networks, metropolitan area networks, and wide area networks.

Point-to-point networks use point-to-point communication channels, that is, communication is limited to a pair of computers that have a connection channel to each other, similar to ** communication.

A broadcast network uses a broadcast channel, that is, multiple computers are connected to a common channel, one station sends information, and the rest of the stations on the channel can receive the information, similar to radio broadcasting.

Extended information: According to the switching mode, computer networks can be divided into circuit switching networks, message switching networks and packet switching networks.

Divided by transmission medium:

1. Cable network: refers to the use of twisted pair.

to connect to the computer network.

2. Optical fiber network: optical fiber is used.

as a transmission medium.

3. Wireless network.

Electromagnetic waves are used.

The type of network that acts as a carrier to achieve data transmission.

By mode of communication:

1. Broadcast transmission network.

2. Point-to-point transmission network.

From the perspective of logical function, a computer network is a computer system that connects multiple computers with communication lines for the basic purpose of transmitting information.

A computer network consists of a transmission medium and communication equipment.

From the user's point of view, a computer network is defined as having a network operating system that can be automatically managed for the user. It completes the resources that the user has called, and the entire network, like a large computer system, is transparent to the user.

Twisted pair, coaxial cable, optical.

Fine. Twisted pair: It usually consists of 8 copper core insulated wires with two pairs of twisted pairs, and the outer insulation layer is coated with different colors.

There are two types of twisted pairs: non-screen twisted pair (UTP) and screen-screen twisted pair (STP). Within 100M transmission distance, the same Category 5 STP transmission rate can reach 155MB s, while UTP can only reach 100MB Usually used for small and medium-sized LAN connections.

Coaxial cable: Compared with twisted pair cables, coaxial cables have strong anti-interference ability and good screen performance, and are often used for connection between devices or in bus-type networks.

Optical fiber: It is divided into single-mode fiber with excellent performance and multimode fiber with low cost. It has three particular advantages over copper cables:

1) Transmission frequency bandwidth, large communication capacity, low signal attenuation, long transmission distance, strong anti-interference ability, wide application range; (2) Strong chemical corrosion resistance, suitable for wiring in some special environments; (3) Abundant raw material resources.

The disadvantages of optical fiber are: brittle texture, low mechanical strength, and high technical requirements for cutting and connection.

Here are a few common performance parameters for network media:

Twisted pair classification: Unshielded twisted pair (UTP) can be divided into Category 3, Category 4, Category 5 and Category 5; Shielded twisted pair (STP) can be divided into Category 3, Category 5, Category 5 and so on.

Main features: unshielded twisted pair is easy to bend, easy to install, flame retardant, and flexible wiring.

The shielded twisted pair is high, difficult to install, requires a connector, and has good anti-interference.

Main uses: Category 3 line is used for voice transmission and data transmission with a maximum transmission rate of 10Mbps; Category 4 line is used for voice transmission and data transmission with a maximum transmission rate of 16Mbps; Category 5 lines are used for voice transmission and data transmission with a maximum transmission rate of 100Mbps.

Network distance: 100 meters per network segment, up to 500 meters after connecting 4 repeaters.

Maximum number of nodes per trunk: Unlimited.

Coaxial cable (obsolete).

Classification: Thick cable; Thin cables.

Main features: high cost of thick cable, difficult installation, long standard distance, high reliability.

The thin cable has low price, easy installation, poor reliability and strong anti-interference ability.

Main uses: The thick cable is the backbone of the large LAN, and the thin cable is used for the backbone connection of the LAN.

Network distance: 500 meters per section of thick cable, the longest network range can reach 2500 meters, the most millet between transceivers, the longest transceiver cable is 50 meters; The longest section of the thin cable is 185 meters, and the longest network range can reach 925 meters, which is the most millet between the two t heads.

The maximum number of nodes per trunk line: 100 thick cables and 30 thin cables.

Classification of optical cables: transmission point modulus class (which can be divided into two categories: multi-mode fiber and single-mode fiber); Refractive index distribution class (which can be divided into two categories: jump-type fiber and gradient fiber).

Main features: transmission frequency bandwidth, large communication capacity; Long transmission distance; Strong anti-interference ability; High resistance to chemical corrosion.

Main uses: long-distance transmission of signals, LAN backbone, transmission of broadband signals.

Network distance: generally 2000 meters.

Maximum number of nodes per trunk: Unlimited.

For example: Twisted pair: Features**Cheap, widely used, mature technology, simple installation. Optical cable: high transmission rate, long transmission distance, not easy to electromagnetic interference, strong confidentiality. :

Wired media: twisted pair, coaxial cable, and optical fiber.

Twisted pair of wired media** is low, and the transmission speed is low; In terms of anti-interference and **, coaxial cable is between twisted pair and optical fiber; Optical fibers have the advantages of low optical signal attenuation, high bandwidth and strong anti-interference ability.

The most commonly used is the network cable.

Generally, there are twisted pairs, coaxial cables, and optical cables.

There are two types of twisted pairs: shielded twisted pair (STP) and unshielded twisted pair (UTP): STP is available in Category 3, Category 5, and Category 5, and UTP is available in Category 3, Category 4, Category 5, and Category 5. Category 3 cable for voice transmission and 10Mbps data transmission; Category 4 voice transmission and 16Mbps data transmission; Category 5 wire is used for voice transmission and 100Mbps data transmission.

The twisted pair cable is 100 meters per network segment and can reach up to 500 meters with 4 repeaters. Maximum number of nodes per trunk: Unlimited.

Coaxial cables are generally divided into two types: thick cables and thin cables. Thick cables are costly, difficult to install, long standard distance, and highly reliable, and can be used in the backbone of large LANs. The thick cable section is 500 meters, the longest network range can be up to 2500 meters, the minimum meter between transceivers, the maximum transceiver cable is 50 meters, and the maximum number of nodes per trunk is 100.

The thin cable has low cost, easy installation, poor reliability and strong anti-interference ability, and is used for the backbone connection of the local area network, with a maximum length of 185 meters per section, a maximum network range of up to 925 meters, a minimum meter between two T-shaped heads, and a maximum number of nodes per trunk line of 30.

Optical cables are divided into transmission point analog-to-digital classes (which are divided into two categories: single-mode optical fiber and multi-mode optical fiber) and refractive index distribution (which are divided into two categories: jump-type optical fiber and gradient optical fiber). The main characteristics of optical cable are transmission frequency bandwidth, large communication capacity, long transmission distance, strong anti-interference ability, and strong chemical corrosion resistance. Optical cables are mainly used to transmit signals over long distances, and the backbone of the LAN is used to transmit broadband signals.

The network distance of the fiber optic cable is 2000 meters, and there is no limit to the maximum number of nodes per trunk.

Wired and wireless, wired: twisted pair, fiber, coaxial cable. Wireless sub-points: laser, microwave.

Answer]: According to the geographical scope of the network, the network can be divided into local area network, metropolitan area network and wide area network by source search. According to the transmission technology of the hall, the network can be divided into broadcast network and point-to-point network.