A brief definition of a computer network
It is defined as a system for connecting, two or more devices using one of the technologies of a communication system, in order to exchange information, resources and data between them available to the network, such as printer programs or applications of any kind, as well as allowing direct communication between users. In general, the study of computer networks is a branch of communication science.
It is possible for the computers in the network to be very close to each other, such as being in one room, and the network in this case is called a local area network (LAN).
It is possible that the network is composed of a group of devices in remote places such as networks between cities or countries and even continents, and such networks are often connected to the Internet or by satellites and the network is called a wide network WAN, there is also in return for that the personal network PAN Which connects a group of devices close to the user.
Knowing the classification of networks : Networks can be classified in several ways, such as according to the way their devices are linked to each other, according to their geographical extension, or according to the technology used in them.
1. Wired network: Twisted wire (or twisted wire) twisted pair is the most popular at the present time for conduction information to get the outward appearance in the appearance of the print in the outward appearance, which is a place of 8 internal wires and not 2 as in the case of a phone, so named because each wire Of the eight they are wrapped together so we have four husbands from that country.
There are two types of stranded wires: A- Shielded Twisted Pair, which is a twisted wire protected against electromagnetic waves, and it is found in factories or areas where these waves are generated, and electromagnetic waves may cause data to be examined or inaccessible.
B-Unshielded Twisted Pair It is an unprotected twisted wire used in natural environments.
Scheduled cable speed from 100 Mbps to 10 Gbps and can transfer data at a maximum distance of 100 meters.
Coaxial Cable, which is the oldest and its speed is less than a twisted wire, and is similar in shape to a TV cable.
– Optical fiber lines The optical fibers are glass fibers, long and thin, and their thickness does not exceed the thickness of a hair. Optical fiber for long distances.
2. Networks that use wireless communication: such as networks that use satellite, radio and infrared signals to connect devices.
- Types of computer networks in terms of geographical extension
- Major urban networks.
- Local networks.
- Personal network.
- An internal network called Can.
- This is used within universities and colleges to connect the college buildings to a single network.
To create a computer network, the following requirements must be met:
1-A”carrier” is a wired or wireless medium.
2-Modem to connect this media to the network.
Now let’s get to know the role of the server. Computers that provide data or resources in current networks are called servers, servers, or servers.
Computers that use this data or resource are called clients
A network device can be a server and a client at the same time
3 – Network drivers (for the server and the client), which are either operational programs for the network operating system or a driver that includes network management as in Windows NT, Windows 2000, Windows Server 2003, Windows Server 2008, XP, Vista or 7 operating systems. else.
In the early days of the network, connected devices were only a few or more fingers than they were connected to a printer. This network is known as a local area network or LAN.
Learn about the benefits of computer networks
You can share information and resources on the network and this provides many benefits:
1- It can share expensive peripherals such as printers as all computers can use the same printer.
2- You can transfer data or various data between users without using FDD floppy disks. Transferring files over the network reduces the time it takes to burn files to discs and then copy to another computer.
3- It can centralize specific programs such as files and financial accounts, as most users may need to use the same program or access the same data together, and thus they can work simultaneously without wasting time.
4- You can make the backup process fully automatic which saves time and makes sure that all your work is safe.
In WANs, resources and information can be shared across larger geographies. This offers a number of advantages:
5- You can send and receive e-mail to and from all over the world, and transfer and deliver messages to several people at the same time in large and different regions at high speed and at low cost.
You can transfer files to and from partners in different locations, or log into the company’s network from home or anywhere in the world.
6- You can access huge resources on the Internet and the World Wide Web “www”
Advantages of computer networks
1- Resource sharing: all workstations or parts thereof can participate in terminal units such as (Disk print) in addition to basic resources such as (database) and file exchange, which reduces the cost of time.
2- Distributed data processing: Network users can download programs and process data at workstations connected to the network, then store their information on the main storage device or on their devices.
3- Administration and security: where the network administrator manages the network by specifying the users who are entitled to access the network through the various workstations, giving a password to each of them and making their permissions limited to accessing resources.
4- Expanding the base of personal computer investors at a low cost: If anyone can access the network through a computer that contains a floppy disk, and thus take advantage of all network capabilities at a low cost.
5- User grouping: the general administrator of the network can collect a number of network users in one group and he can choose one of the users to be the manager of this group.
7- The ability to access other operating systems through the network and deal with them.
Computer network requirements
To create a computer network, you must have several tools and devices to connect computers. Of these devices:
- At least two computers.
- Ethernet NIC.
- A wired or wireless means of transmission
- Hub or switch
- A communication protocol that defines the algorithm for addressing network components.
- Network operating system.
- There are some other tools that differ according to the type of network, but the basic requirements are mentioned above.
- There are other types of large networks that may require a router to connect two networks with a different address or to link a group of virtual networks.
- A VTP can be called a network connected in only one building to a local network.
In the event that we wish to connect to a remote network, we need a modem (CSU / DSU), which is an important broadband network device.
Note: The work of the hub cannot be likened to a transformer because the switch is more advanced and has faster performance than the hub.
Types of networks by extension
Typically, this type of network covers small geographic areas such as universities, a branch of a large company, or a computer network at home.
The number of computers in this type ranges from two to at least 500, and to link these devices we need a device called a hub or a switch, meaning the hub or bus, to work on linking the devices to each other and enabling them to communicate with them. each other.
It is usually used to connect devices in this type of network wiring, and it is of a special type for transmitting data or wireless devices.
If allowed, the caller on the network can see the information and files on other people’s devices.
This type is usually used in small enterprises and universities in order to facilitate work and quickly transfer shared information between departments. And they fall within a limited reach, for example (office work – internal institutions – limited companies)
Local Area Network : Local area networks allow computers and devices that are close together, usually using the same switch or router – to connect, share files and complete tasks. Local networks only consist of everyday equipment (such as desktops, laptops, tablets, and printers), a router and / or switch, and Ethernet cables or wireless cards, and are relatively inexpensive to set up and are common in homes. Despite its lower capacity, the proximity and the resulting lower costs usually result in faster use of the technology on the local network.
Hence, this network rating is usually the component with higher speed and fastest communication equipment than other network ratings such as equipment using the same speed. This is because it generally requires less investment to get the smaller network to operate equipment faster.
Therefore, local networks are usually considered
They are the building blocks for creating larger networks.
Ethernet cables, such as Cat5, Cat5e, Cat6, and Cat6a, can be used to connect computers to a network.
In cases where fiber is available for the home (or similar), copper cable may also be used at some point. Wi-Fi is becoming one of the most popular ways to connect wirelessly via a local area network.
Wide area network (WAN)
Wide network: It is all networks that extend over a wide geographical area and may be a city, a continent, or the whole world.
There are large private networks, for example, a company that has more than one branch around the world, it is a large network and has a central computer and its own database. Among the most important devices used in wide networks are routers. These devices connect networks of different IP addresses to each other via multiple routing protocols.
Compasses are like telephone lines and satellites, and the most famous example of a wide area network is the Internet because it covers the world and connects many networks together.
(Wide area network)
WAN is a network that covers a large area using private or public transportation.
The best example of the wide network is the Internet, which can help connect anyone from any region of the world.
Many companies and governments use the WAN to conduct business from anywhere in the world.
Also, broadband networks are largely responsible for commercial activities that take place around the world (i.e. a British company that does business with a company in China). The basic definition of a wide network includes a network that can extend to regions, countries, or even the world.
However, in practical application, WAN can be thought of as a network that is used to transfer data over long distances between different local networks,
Model: Comparison of LAN and WAN: LAN which stands for Local Area Network, and WAN which stands for Wide Area Network, are two types of networks that allow communications between computers.
As the naming conventions suggest, LANs are intended for smaller and more local networks – at home, business, school, etc. – while wide networks cover larger areas, such as cities, and even allow computers in different countries to communicate.
Local networks are usually faster and more secure than wide area networks (WANs), but Wide Area Networks (WANs) allow for a much wider connection.
Although LANs tend to be owned, managed, and managed within the organization by the organization in which they are deployed, a WAN typically requires the connection of two or more component local networks over the public Internet or over a private connection established by third-party connections.
LAN, allows computer users to communicate and communicate with each other regardless of location. Typically, a property is owned, controlled, and operated by a single person or an organization.
No single organization owns WANs (like the Internet), but is subject to collective ownership or management spread over long distances, using technologies such as SONET, Frame Relay, and ATM. A WAN allows various local area networks to communicate with other local area networks through technology such as routers, hubs, and modems. There are four main options for connecting to the WAN: leased line, circuit switching, packet switching, and call relay. Leased lines are a point-to-point connection between two systems. A circle key is a dedicated circle path between two points. Packet switching includes devices that transfer packets over a common point-to-point or point-to-multipoint link over a carrier network. Relay relay is similarly packet switching but it uses fixed length cells instead of variable length packets.
And local networks are becoming more and more popular in many places like offices, companies, homes, etc. The main reason for its growing popularity is that it is cheaper to install and provides higher transmission speeds. Local networks provide speeds of 80 or 90 Mbps due to the proximity of computer systems to each other and the absence of network congestion.
In comparison, WANs can provide speeds between 10 and 20 Mbps. Local networks also provide better security compared to Wan networks, which are more accessible with people who know how to hack systems.
WAN and LAN networks can be secured with firewalls, anti-virus and spyware.
In general, encapsulation describes the basic contents of an item among other purposes.
computational jargon, encapsulation is used in a variety of applications to mask or encapsulate information.
In communication networks, encapsulation can be used to combine different types of protocols or transport formats into a single protocol.
The encapsulation protocol encapsulates another protocol, so that networks can use the encapsulated protocol to transport the network.
The benefit of encapsulation is that only one protocol is used in the network.
To illustrate this: OSI has divided the work before the transfer into 7 basic layers, starting with the application layer, which secures the basic information, adds its head to it, then sends it to the bottom layer, then adds its own information and sends it to the lowest layer until it reaches the physical layer that sends The encapsulated information as electrical signals to the receiver who performs the opposite process of packaging, i.e. decoding the package.
so that the physical layer in the future receives the information and sends it to the upper layer, which in turn decodes part of the package from the information according to its correspondent in the sender layer and then sends it to the upper layer And so on until you get to the application layer and here you remove its packaging using the information received to the user is displayed.