Network models classify the network on the basis of services and geographical area.
1). Network based on services:
Based on how the computers in a network are configured and how they access information, networks are classified into two types;
a). Peer-to-Peer Network:
In a peer-to-peer network, all computers have an equal relation to one another. There is not any computer, which can be regarded, as superior to another computer. All computers are equal and therefore are known as peers. Any computer in peer-to-peer network can functions as both client and a server simultaneously. Any computer in the network is capable of accessing data, software and other resources directly without any central controlling mechanism. Peer-to-peer network are also called as workgroups.
Advantages of using peer-to-peer network:
• Peer-to-peer networks are easy to build and operate
• Peer-to-peer networks are inexpensive to operate
• The network software used to operate peer-to-peer networks are simple and easy to operate.
• If any computer in a peer-to-peer network fails, then the resources on only that computer becomes unavailable without hampering the availability of resources on other computers.
Disadvantages of using peer-to-peer network:
• The required resources are difficult to find quickly because it could be in any one of the computers.
• Peer-to-peer networks are not very secure.
• A peer-to-peer network becomes very difficult to manage and operate when the number of computer involved exceeds 15 to 20.
b). Client-Server Network:
Client server networks have become standard models for networking. In client-server network, there is a clear distinction between the computers depending upon their functionality; clients and servers. Servers are powerful computers dedicated to managing files or documents (file server), printers (print servers), web pages (web servers) etc. Client are less powerful computer on which users do their job. Client depends upon server computers to access required resources.
Advantages of using client-server network:
• Since the resources are usually located in servers, the resources are easy to find.
• Client-server network can be made very secure. The resources on the server can be controlled very tightly by identifying, who can access the resources and who cannot.
• Client-server network are very scalable. i.e. the number of clients that can be connected in a client-server network is not limited.
Disadvantages of using client-server network:
• It cost more to implement and operate than the peer-to-peer network.
• If the server in a client-server network fails, then the clients cannot access any resources.
• Specialized software is needed to implement a client-server network.
2. Network based on Geographical Area:
1). Network based on Geographical area:
Based on size and distance coverage of networks, the computer network is divided into three types:
a). Local Area Network:
A local area network (LAN) refers to a combination of computer hardware and transmission media that is relatively small. Normally, LAN is entirely contained within a school, college, building etc. LANs is typically comprised of only one transmission media type such as coaxial cable or twisted pair cable but never both. The features of LAN are;
• It covers short geographical area.
• LANs are characterized by comparatively high speed communication.
• LAN uses only one kinds of cable.
• Complete ownership by single organization.
b). Metropolitan Area Network:
A Metropolitan Area Network (MAN) is a network that is larger than a LAN. It is called metropolitan since it normally covers the area of city. Different hardware and transmission media are often used in MAN because they don’t require complete access to locations between the network sites. The features of the MAN are;
• It covers large geographical area with respect to LAN.
• MANs typically used when you need to connect dissimilar system within a single metropolitan.
• It is owned by single or multiple organizations.
• It uses private or public connection mediums.
c). Wide Area Network (WAN):
A Wide Area Network is a network of connecting two or more computers generally across a wide geographical area such as cities, districts and countries. WANs interconnect LANs which may be at the opposite side of a country or located around the world. It uses telephone lines, communication satellite and other long range communication links to connect the computers and network. Internet is an example of WAN. The characteristics of WAN are:
• It covers a large geographical area.
• Transmission cost is high
• Transmission error is higher than LAN
• It is owned by multiple organizations.
• It uses public connections mediums such as telephone lines, wireless technology etc.
• Owned by multiple organization.