Network and communication
Network: A computer network is a collection of computers and hardware components interconnected by communication channels that allow sharing of resources and information
Types of Network:
Local Area Network(LAN)
Metropolitan Area Network(MAN)
Wide Area Network(WAN)
LAN: When computers located within a small geographical area such as office or a University Campus are connected together we call it a Local Area Network.
MAN: The geographical range of MAN is bigger than LAN. It covers a small city.
WAN: Wide area network span broad geographical distances, ranging from several miles to across entire continents. WAN may consist of a combination of switched ...view middle of the document...
2. A computer network can provide a powerful communication medium among employees.
3. Many companies are doing business electronically with other companies, especially suppliers and customers.
4. Doing business with consumers over the Internet.
Some of the popular uses of the Internet for home users are as follows:
1. Access to remote information
2. Person-to-person communication
3. Interactive entertainment
4. Electronic Commerce
People on the road and sea may use their portable electronic equipment to send and receive telephone calls, faxes, electronic mail, surf the web, access remote files, and log on to the remote machines.
A popular feature of many networks is newsgroups or bulletin boards whereby people can exchange messages with like-minded individuals.
Network Topology refers to the physical data path that traffic takes across the network. Three basic types of topologies are bus, star and ring.
In a bus topology
Each node is connected to a common cable called a bus.
Each node has a unique address.
All nodes will receive a message, but only the addressed node is to respond.
• If one node is down, the network is still available.
• Fewer wires or lines are needed.
• Difficult to administer/troubleshoot.
• Limited cable length and number of stations.
• If there is a problem with the cable, the entire network goes down.
• Performance degrades as additional computers are added or on heavy traffic.
Fig: Bus topology
In a star topology a central host computer connected to a number of small computers or terminals. This topology is useful for applications where some processing must be centralized and some can be preformed locally.
• Good performance
• Easy to set up and to expand.
• Any non-centralized failure will have very little effect on the network
If the central host computer is down, the network will come to standstill.
In a ring topology all computers are connected by a closed loop in a manner that passes data in one direction from one computer to another.
• Data is quickly transferred.
• The transmission of data is relatively simple as packets travel in one direction only.
• Adding additional nodes has very little impact on bandwidth
The main disadvantage of a ring is larger communication delays if the number of nodes increases.
Model of Connectivity for networks
Reference model: A reference model is a generic framework for thinking about a problem.
Protocol: A protocol is a statement that explains how a specific task will be performed.
Open system Interconnect (OSI) Model: OSI model is an international reference model developed by the International...