NETWORK CATEGORIES!
Networks are categorized into two major categories: Local Area Network (LAN) and Wide Area Networks (WAN). The category into which a network falls is determined by its size or the area it covers. A LAN normally covers an area of few kilometers; a WAN can be worldwide. Networks of a size in between are normally referred to as Metropolitan Area Network (MAN) and spans tens of miles.
LAN:
A LAN is usually privately owned and links the devices in a single office, building or campus. It is designed to allow resources to be shared between Personal Computers or Workstations. The resources to be shared can include hardware (e.g., a printer), software (e.g., an application program) or data.
In LAN, one of the computers connected to it acts as a main computer (called the Server) with a large capacity of hard disk and a set of software that can be accessed from other computers, called Workstations. Moreover, data exchange can be done between computers in a LAN much faster than the data rates of other networks (WAN and MAN). Early LANs had data rates in the 4 to 16 megabits per second (Mbps) range. Today, LAN speeds are normally at 100 or 1000 Mbps.
WAN:
Wide Area Networks (WAN) generally cover a large geographical area, which includes countries, continents or even the whole world and provide long distance transmission of data between two nodes located anywhere within the range. Based on the type of connection they use, WANs are of two types: Switched WAN and Point-to-point WAN. A best example for the switched WAN is Internet. A dial-up line of the telephone network is an example for point-to-point WAN.A point-to-point WAN (also called as Circuit Switching network) uses a dedicated communication path for establishing the connection between two nodes. The path is a connected sequence of physical links between nodes. Data generated by the source node are transmitted along the path as rapidly as possible, without delay.
Switched WAN is also called as Packet Switching network and sends data in a sequence of small chunks, called Packets. Each packet is passed through the network from node to node along some path leading from source to destination. At each node, the entire packet is received, stored briefly, and then transmitted to the next node.
Switched WAN can be used to connect nodes of two different networks (LAN/WAN) through a connecting device that acts a as a bridge between two types of networks. Examples for switched WAN are: X-25, Frame Relay, and Asynchronous Transfer Mode (ATM) network.
MAN:
MAN is a network with a size between a LAN and a WAN. It normally covers the area inside a town or a city. It is designed for customers who had a high-speed connectivity, normally to the Internet, and have end points spread over a city or part of a city. Cable TV network and high-speed telephone network (leased lines) are examples of MAN.
Interconnection of Networks (internet):
The term internet (inter network) refers to a network which is formed by inter connecting two or more networks of same type or different types (LAN, WAN & MAN). This type of network is only possible with the help of interconnecting devices such as Routers and Bridges.
LAN Vs. WAN:
There are several key distinctions between LAN and WAN. Some of them are as follows:
Scope: The scope of the LAN is small, typically a single building or a cluster of buildings, whereas WAN covers a large geographical area.
Ownership: A LAN is always owned by a private organization, whereas WANs are often owned by the public. At least a significant fraction of the network assets (in WAN) are owned by the public.
Speed: The internal data rates of LANs are typically much greater than those of WANs.
