Today, enterprises and institutions have been widely used LAN, the main purpose of which provide access to network-wide (information, software and hardware) resources. In addition, LAN enterprises allow employees to quickly share information with each other.
LANs are used to solve such problems as:
- Data distribution. Data stored in a local network to a central computer and can be accessed by the workstations. In this regard, it is not necessary to have each workplace drives for storing the same information;
- Allocation of resources. Peripheral devices can be accessible to all users on the LAN. Such devices may be, for example, a scanner or a laser printer;
- Distribution programs. All users can share the LAN have access to programs that have been centrally installed on one computer.
Basics of Local Area Networks
Local area network (LAN) is a compound with multiple PCs using appropriate hardware and software. In local networks the data rate is high in comparison with the protocols of the WAN protocols are relatively simple, there is no redundancy of communication channels.
LANs depending on the administrative relationships between computers are divided into:
- hierarchical or centralized;
Local network according to the physical and logical relationships between different computer architectures (Ethernet, Token Ring, FDDI, etc.) and topology (bus, ring, star, etc.).
In local area networks implemented technology “client – server”. Server – an object (computer or program) that provides maintenance services, and the client – an object (or computer program) that requests the server to provide these services.
In ad-hoc networks may be simultaneously server and the client, i.e. use the resources of another computer or the same PC, which he provides resources.
Server in hierarchical networks can be a client server only a higher level of the hierarchy. Hierarchical networks are called network with a dedicated server. Computers on the local area network, called nodes. Each node can be a server or workstation.
Peer to Peer (single level) LAN
- An ad hoc network – a network of peer computers (workstations), each of which has a unique name and password to log into the computer. An ad-hoc network does not have a central PC.
- An ad-hoc or one-tier LAN
In ad hoc network, each workstation can share all of its resources with other workstations network. The workstation can share some resources, but may not provide any resources to other stations. For example, some hardware (scanners, printers, hard drives, drives CD-ROM, and others.) Connected to a separate PC used together in all workplaces.
Each user is the administrator of an ad hoc network on your PC. Peer networks are used for networking a small number of computers – no more than 10-15. Peer network may be arranged, for example, using the Windows 95, 98, 2000, Windows XP or other operating systems.
For access to the resources of workstations in an ad hoc network log folder in My Network Places, double-click the My Network Places icon and select View workgroup computers. After this, the screen will display computers that are part of an ad hoc network by clicking on the icons of computers, you can open the logical drives and folders with a network-wide resources.
Hierarchical (multilevel) LANs
Hierarchical LAN – local area networks in which there are one or more special computers – servers on which information is stored, shared by different users. Hierarchical LANs – is usually a LAN with a dedicated server, but there are unallocated network and server. In networks with a listen server function workstations and servers combined. Workstations, included in a hierarchical network can simultaneously organize among themselves peer LAN.
Hierarchical or multilevel LANs
Dedicated servers are usually a high-performance computers with high-capacity hard drives. Installed on the server network operating system, connected to it all external devices (printers, scanners, hard drives, modems, etc.). Provisioning server in a hierarchical network is at the user level.
Each user must be registered with the network administrator with a unique name (login) and users must assign a password under which will be included in the PC and the network. In addition, when users log network administrator allocates to them the necessary resources on the server and access rights to them.
The computer from which the access to information on the server, called workstations, or customers. They installed a standalone operating system and the client part of the network operating system. In the local operating systems Windows 95, 98, 2000, Windows XP is on the client side such as network operating systems: Windows NT Server, Windows 2003 Server.
Depending on the usage of the server in the hierarchical LAN distinguish the following types of servers.
File server. In this case, the server are processed jointly shared files and programs.
Database server. Located on the server network database. The database server can be replenished from different workstations and provide information on requests from workstations.
Access Server – a dedicated computer on your local network for remote processing tasks. The server performs the job received from a remote workstation, and sends the results to a remote workstation. In other words, a server for remote access (e.g., mobile computer) to LAN resources.
Server – printing. For low-power computer connected enough performance printer that can print information from several workstations. The software organizes the print queue.
Mail server. The server stores information, send and receive both the LAN and external modem. The user can view his name entered the information or send via e-mail server your information.
Peer and hierarchical LAN has its own advantages and disadvantages. Selecting type LAN depends on the requirements imposed on its cost, reliability, processing speed, privacy information, etc.
Author: Jaringan Komputer