One is a network server; The second is the network workstation; The third type is network adapter, also called network interface card or network card; The fourth type is the connecting wire, the scientific name is "transmission medium", which is mainly cable or twisted pair, and there are also uncommon optical fibers. We connect these hardware, and then install special software to support network actions, including system software and application software, then a local area network that can meet the needs of work or life is formed.
2. Web server
In general, a network server refers to a file server. File server is the most important hardware equipment in the network, which is equipped with network operating system, system management tools and various applications. This is the basic configuration necessary to form a client/server LAN. For peer-to-peer networks, each computer is both a server and a workstation.
In Novell network, there are two other servers: one is a print server, which is used to manage and control the printing tasks in the network, and the other can support 16 printers; The second is asynchronous communication server, which is mainly used for remote communication and network connection with other asynchronous hosts. These two kinds of servers are relatively rare in general LAN.
It would be better if you can buy a special file server, because there are special considerations in hardware. Isn't it said that the access speed of the server hard disk has a great influence on the network? Therefore, dedicated servers give consideration to data storage, speed and reliability, and generally apply fault-tolerant technologies such as hard disk mirroring and duplex. But generally speaking, a small local area network can meet the requirements by using a P ⅱ microcomputer, one or several GB large-capacity hard disks and a 32-bit network card.
3. Network card
Network card is an integrated circuit card inserted in the I/O slot of a microcomputer, which is used to send and receive different information frames and realize microcomputer communication. According to the bus type, it can be divided into ISA network card, EISA network card and PCI network card.
The working principle of the network card is similar to that of the modem, except that the input and output of the network card are all digital signals, and the transmission speed is much faster than that of the modem.
There are 16-bit network cards and 32-bit network cards. The representative product of 16 bit network card is NE2000, which is very popular in the market. Some can't be named, and they are usually used in workstations. The representative product of 32-bit network card is NE3200, which is generally used in servers, and there are also compatible products on the market. Whether a network uses 16-bit or 32-bit network cards, it is best to use the same brand to ensure good compatibility. Generally speaking, the quality of compatible products is ok, and the impact on Xiaolan is not obvious. You should buy the plug-and-play model at present.
There are three specifications for the interface of the network card: thick coaxial cable interface (RJ-45 interface); Thin coaxial cable interface (BNC interface); Unshielded twisted pair interface (RJ-45 interface). Generally, network cards only provide one interface, but some also provide two or even three interfaces.
The small red and green lights are the working indicators of the network card. The red light indicates that data is being sent or received, and the green light indicates that the network connection is normal, otherwise it is abnormal. It is worth noting that if the length of the line connecting two computers exceeds the specified length (twisted pair 100 m, thin coaxial cable 185 m), even if the connection is normal, the green light will not light up.
4. Public transmission media
Coaxial cable and unshielded twisted pair are usually used as transmission media.
Thick coaxial cable: the model is rg-11(10base5), which adopts AVI interface and is mainly used for trunk construction. Thin coaxial cable: RG-58 (10BASE2) with BNC interface, mainly used for network connection between computers. However, due to the loose connector and poor reliability, it is gradually replaced by twisted pair.
Twisted pair: Twisted pair is divided into shielded twisted pair (STP) and unshielded twisted pair (UTP). At present, UTP twisted pair is divided into five categories and three categories. Generally, three types are used for small LAN (100M network) and five types are used for large LAN with high reliability and high speed (100 m network), with RJ-45 interface.
5. Center
In the computer classroom, the tree network is to select workstations to connect to the hub and then connect to the server. HUB, also known as hub, is a kind of special equipment that completes the connection of multiple devices in a centralized way and provides error detection ability, network management and other related functions.
There are three types of hubs:
A 1 passive hub without any data to be transmitted is called a passive hub;
2 active hub, which can regenerate signals and monitor data communication, is called active hub;
Smart hubs that can provide network management functions are called smart hubs.
There is also a special hub called repeater, which is used to connect two LANs of the same type or expand a LAN. When we install a local area network, the physical distance exceeds the specified length of the line, we can use it to expand; Repeater can also receive the signal from one network, amplify it and send it to another network, thus playing the role of connecting two local area networks.
Another kind of repeater-like device is called a bridge, but the bridge has an additional function of "filtering frames". Although the physical connection distance of a network is within the specified range, due to the heavy load, a network can be divided into two networks by a bridge. This is because the bridge will check the sending address and destination address of the frame. If these two addresses are in this half of the bridge, the other half of the bridge will not be affected by this frame, which can reduce the communication load of the whole network. This function is called "filtering frames".
To connect networks that follow different network protocols, you must use a router. If the two networks are not only different in network protocol, but also very different in hardware and data structure, then use a Getway. However, these two things are hardly used in general LAN.
6. Cable (twisted pair) and network card (or hub) connection
Thin coaxial cable needs two connectors to connect network card or hub, one is BNC connector and the other is BNCT connector. When we connect two computers, we should cut off the cable first. The cable length of two adjacent computers is generally 1 m ~ 2 m, not less than 0.5 m. Then use a knife to peel off the sheath of about 1.5 cm at the end of the cable, put on the thin metal tube in the attachment, and cut off the thin metal shielded wire in the thin cable by about 0? 6 cm long, revealing a fine core wrapped in hard transparent plastic. Carefully peel off the hard transparent plastic by 0.5 cm to expose the copper core of the thin cable. Insert the copper core into the cavity of the fine metal needle in the accessory, then put it into the small groove at the front end of the wire clamp for clamping, and put on the main connector, so that the small end is inserted into the cable first, and the fine metal tip is flush with the rest. Pull up the thin metal tube, cover the rear end of the main connector, and clamp it with the hexagonal notch in the middle of the clamp, and a connector is completed.
We connect the BNC connector of the cable with the BNCT connector, and the third end of the BNCT connector is inserted into the BNC interface of the network card. At this point, the cable is connected to the network card. This connection will lead to two empty connectors at both ends of the network that no computer can connect, so we plug them in with terminal resistors, and one of them must be grounded.
Twisted pair requires RJ-45 connector. Just connect the RJ-45 connector (crystal head) to both ends of the twisted pair according to a certain standard, and then plug the RJ-45 connector into the RJ-45 interface of the network card to realize the connection. Therefore, a key link in network construction is to do a good job of connecting network cables.
7. The special function of eight wires in twisted pair.
The meaning of RJ-45 core wire;
8. Installation of network card
Generally speaking, it is easy to install a plug-and-play network card on a Pentium-class microcomputer. The installation of various network cards is slightly different. If an error is reported, it is easy to solve it by carefully reading the manual and the accompanying manual, and checking the BIOS address, interrupt value, I/O address and DMA one by one, as well as the interface type of the network card (the cable is BNC and the unshielded twisted pair is UTP).
the second question
My Network Neighborhood-computers nearby-the number of computers to visit.