OBJECTIVE
The objective of this topic to understand networks of Local and wide area communication.This topic will help to understand network connectivity issue of any organization.Various types of data communication and how this will work this is covered in this topic.
DATA COMMUNICATION
Data may be sent for short distances or for long distances also .In case of short distances digital data can be sent direct over direct wire digital link it may be through simple copper conductors.In case of long distances we used digitally modulated analog carrier signals.
ELECTRONIC MAIL
In such communication we can transfer data in form of text from one place to another .Each user having a mail box in which the message are stored which are sent by sender and from mail box we can access the messages.
An email data communication system consists of
1.Source computer and destination computer
2.Modems which is data communication devices\
3.Cable which works like a communication channel
4.Data communication Software
DIAL-UP LINES
In this data communication two computer systems use dial up lines connected by modems and using telephone network.It is the simple method .we can connect two remote computer easily.In case of Dial-up lines the charges or cost depend on distance between two user and time spent or how long connection is made.It is the cheapest transfer medium.
LEASED LINE
It is dedicated data communication where dedicated link established between the source user and destination user.It is high performance data communication because leased line is permanently allocated by telephone network.In leased line cost is fixed i.e same rate is charged whether you used communication facility or not.
INTERNET CONNECTIVITY
The connection can be either wired or wireless.The wired connections use PSTN(Public switched telephone network) /PSDN(Public switched data network.The wireless connection in wide concept using satellite communication.Many internet service provider provides internet servers like GIAS(Gateway Internet Access Service) of TATA Communication,NICNET(National Informatics Centre Network) .The user get connected with internet through Internet Server
There are mainly two ways of connection methods
a) On-Line Connectivity
b)Off-Line connectivity
INTRANET
Intranet and Internet are two different things.Intranet is nothing but an application of the internet technology to a closed network where every user is not allowed to connect with Intranet.Intranet uses Internet-derived communication protocols(TCP/IP),IP network and a user interface like Web browser .Protocol is nothing but set of rules which helps electronic devices to communicate with each other.
It i used for corporate application.
LAN
In LAN(Local area network) more than one computers connected together typically a single building,office,home and communicate with each other and also share computing devices like file servers,printers,scanners etc.This are called node and this nodes are connected with LAN through Interface Hardware called adapter
The network consists of shared transmission medium having data rate 100Mbps or 10Gbps.
Many different types of media are used for LAN
1.Guided Media
In this media the transmitting signal follow a narrow path and will behave predictably.The three most commonly used media are Twisted-Pair wiring ,coaxial cable and optical fiber cable.
2.Unguided Media
It can be used as physical paths to carry electrical signals.The atmosphere and outer space are example of unguided media which can carry microwave infrared light waves and radio waves.
HUB
It acts as a central point for LAN cable.Repeater is the example of hub which simply connect cables together and regenerate data thereby passing data from one device to another.There are also hub which connect network segments and routers ,which connect different types of both local and wide area networks.This types of hubs are specialized and related to the network they are used in.They are typically installed in very large and complex networks.
BRIDGE
In a network if more devices are connected more collision will happen and therefore the avg throughput will go down so as a solution if we divide the network into separate networks or segments and within each segment device will continue to communicate with each other then throughput remain same and to do this a device called bridge is often installed that connects to these network.
SOFTWARE
Software is required by the network to operate which is Known as NOS(Network Operating System).NOS support peer to peer architecture and also support Client/Server architecture.Device drivers program is required for adapters installed in LAN.
