metropolitan area network

a metropolitan area network 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 need a high speed connectivity ,normally to the internet and have endpoints spread over a city or part of city....

a good example of a MAN is the part of the telephone company network that can provide a high speed DSL line to the customer ...another example is the cable TV network that originally was designed for cable TV ,but today can also be used for high speed data connection to the internet.....

wide area network

a wide area network provides long distance transmission of data ,image ,audio and video information over large  geographic areas that may comprise a country ,a continent or even the whole world .....a WAN can be as complex as the backbones that connect the internet or as simples as a dial up line that connects a home computer to the internet .....
we normally refer to the first as a switched WAN and to the second as a point to point WAN...
the switched WAN connects the end system ,which usually comprise a router that connects to another LAN or WAN..
the point to point WAN is normally a line leased from a telephone or cable TV provider that connects  a home computer or a small LAN to an internet service provider ....

local area network

a local area network is usually privately owned and links the device in a single office ,building or campus ....
depending on the needs of an organization and the type of technology used ,a LAN can be as simple as two PCs and a printer in someone home office....or it can extend throughout a company and include audio and video peripherals ....currently LAN size is limited to a few kilometers...

LANs are designed to allow resources to be shared between personal computer or workstation..
the resources to be shared can include hardware,software or data...a common example of a LAN ,found in many business environment ,links a workgroup  of task related computers ....
early LAN had data rates in the 4 to 16 Mbps range ...

network modules

computer networks are created by different entities ...standard are needed so that these heterogeneous networks can communicate with one another ...the two best known standards are the osi models and the internet model ....

the OSI model defines a severe layer network the internet model defines a five layers network....

CATEGORIES OF NETWORKS:-
today we speak of networks we are generally referring to two primary categories local area network and wide area networks ....the category into which a network falls is determined by its size ....A LAN normally covers an  area less than 2 meter....a WAN can be worldwide ....network of a size in between are normally referred to as metropolitan area networks and span tens of miles....

introduction

today we will discuss about the networks.....
a network is a set of device connected by communication links ...a node can be a computer,printer or any other device capable of sending and receiving data generated by other nodes on the networks...

network criteria
a network must be able to meet a certain number of criteria ..
the most important of these are performance ,reliability and security...

performance:-
performance can be measured in many ways including transit time and response time....transit time is the amount of time required for a message to travel from one device to another...response time is the elapsed time between an inquiry and a response....