1, network cable
Network cable is essential for connecting local area network. There are three kinds of common network cables in LAN: twisted pair, coaxial cable and optical cable. ? Twisted pair is a data transmission line composed of many pairs of wires.
It is characterized by its low price, so it is widely used, such as our common telephone line. It is used to connect RJ45 crystal head.
It is divided into STP and UTP, and UTP is usually used.
2. Router
A router is a hardware device that connects two or more networks and acts as a gateway between networks. It is a special intelligent network device that reads the address in each packet and then decides how to transmit it.
It can understand different protocols, such as Ethernet protocol used in LAN and TCP/IP protocol used in Internet. In this way, the router can analyze the destination addresses of data packets from various types of networks and convert the addresses of non-TCP/IP networks into TCP/IP addresses, and vice versa;
Then according to the selected routing algorithm, each packet is transmitted to the designated location according to the best route. Therefore, routers can connect non-TCP/ IP networks to the Internet.
3. Repeater
A repeater (RP repeater) is a connection device that works at the physical layer. It is suitable for the interconnection of two same networks, and its main function is to extend the network transmission distance by forwarding or forwarding data signals. Repeater is a network device that regenerates and recovers signals: the physical layer device of OSI model.
Repeater is used to extend the network distance in LAN environment, but it is not a network interconnection device and works in the physical layer of OSI. Repeater has the function of amplifying and regenerating the signal on the line, which is used to extend the length of LAN segment (only used to connect the same LAN segment).
Step 4 convert
Switch, which means "switch", is a network device used for electric (optical) signal forwarding. It can provide a dedicated electrical signal path for any two network nodes accessing the switch. The most common switch is an Ethernet switch. Other common ones are telephone voice switch and optical fiber switch.
5. Center
Hub is called "hub" in English. "Hub" means "center". The main function of the hub is to regenerate, shape and amplify the received signal, so as to expand the transmission distance of the network, and at the same time concentrate all nodes on the node centered on it.
It works in the first layer of the OSI (open system interconnect) reference model, that is, the "physical layer". Hub, like network card, network cable and other transmission media, belongs to the basic equipment in local area network, and adopts CSMA/CD (carrier sense multiple access technology with collision detection) medium access control mechanism.
Each interface of the hub only sends and receives bits. When it receives 1, it forwards 1, and when it receives 0, it forwards 0 without collision detection.
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