This post is all about internet protocols and their functions and also different types of connectivity technology you use .
Internet protocols and their functions :
* ISP ( intternet service provider ) – a company that provides clients access to the internet .
* Host – a company on TCP/IP network such as the internet .
* WWW – World wide web (graphical extension of internet that allows users to search for and view information easily with the help of a browser )
* Browser – Software basically made to understand and run HTTP content .
* HTTP ( hyper transfer protocol ) – A TCP/IP protocol defines how world wide contents is downloaded and shown in your browser .
* FTP ( file transfer protocol ) – Another Tcp/IP used to transfer large files over the internet . Client can use both graphical and command line .
* E- MAIL – Electronic mail is way of receiving and sending messages over the intrenet .
* DHCP ( Dynamic Host Configuration Protocol ) – It is used to configure automatically Tcp/IP info. for hosts on the network .
* WINS ( Window internet Name Service ) – It makes it easier to find resources on a Microsoft Network and manage microsoft Netbios-based names .
* DNS ( Domain name system ) – It makes it easier to find resources on TCP/IP network and manages internet host and domain names .
CONNECTIVITY TECHNOLOGY :
- ISP ( INTRENET SERVICE PROVIDER )
ISPs basically provide the technical gateway to the internet . Services provided by ISP are :
* Email services through POP3 and SMTP servers
* Internet routing
* Internet identity through ip addresses
* Internet news services
Popular service providers are AOL , Earth link etc.
- LAN Access
Internet access can basically be provided through the existing local area network structures and these arrangements may involve a third party . FUnctions
* As a cache
* As a firewall that provides protection .
* As a proxy server
* Routing services
- DIAL UP ACCESS
When a computer uses telephone network to communicate to internet , it is refered to as a DUN (dial-up networking) . However , to overcome signal deterioration , a modem convert signal which are best suited
for transmission over wire . Modem helps to convert digital signal of PC into serial , analog which are better suited . A modem can be either external or internal device. It works in three different modes .
* Simplex mode – when modem is used to send signals in only one direction .
* HALF duplax mode – Both modems can exchange data , but only in one direction at a time .
* FUll duplex mode – It allows both modem to send and receive data simultaneously by multiplexing the send and receive signal frequencies .
- ISDN ( INTERNET SERVICES DIGITAL NETWORK )
It requires digital modems to offer high speed access to public telephone system . The main goal of ISDN is to use existing infrastructure of networks and telephone lines and able to transmit digital data , voice and other services like reservations etc. There are three levels of ISDNs :
* BRI ( Basic Rate Interfaces ) – BRI usually provides residential users . The BRI info channels exist as a pair of 64kbps channels and a 16 kbps control channel . These are used to receive and transmit data and voice .
A residential telephone wiring consists of four wire cable up to seven devices can be connected to these wires .
* PRI (Primary Rate Interfaces ) – PRI services support very high data rates needed for live video transmissions . The operating cost is more expensive than BRI service .
* BISDN ( BROAD band ISDN services ) – IT is fastest ISDN service ( up to 622 MBPS) , but most expensive .
- DSL (Digital subscriber line)
DSL communications requires a special DSL modem also known as ATU (ADSL Terminal unit ) . DSL provides a high bandwidth connection service up to 9 Mbps . Depending on the DSL service the splitting may be manually installed at the subscriber location , or the signal splitting may be provided remotely from the telephone exchange carrier local office .
- Speed is much faster ( 1.5 Mbps ) whereas in regular modems it is 546 kbps .
- The internet connection can remain open while phone lines is used for voice calls .
- DSL service employs telephone wires between the home and the telephone switching center .
- A DSL connection works better where user is closer to the provider’s central office .
- ADSL connection is faster for receiving data than its sending speed .
- DSL is not available in all locations .
The cable companies offers special cables modems that attach the pc to an existing cable TV (CATV) . Cable modem features two main connections . One to the host computers POrt 10/100 Ethernet adapter and the other to the CATV coaxial cable outlet on the wall . Cable modems employs F-type connectors to attach the coaxial cable from the cable systems to the cable modem .
The TV signals are transmitted up to a satellite in orbit around the world and then retransmitted . Download speed is faster up to 1.5 Mbps and upload speed are limited to the 56 Kbps . DISH holds the device known as LMB ( LOW NOISE BLOCK ) converter that helps in receiving satellite signal and removing the noise . RG -6 coaxial cable is used to connect the LMB and satellite receiver .
WIFI (wireless fidelity ) is a trademark used by wireless LANs that operate on unlicensed power covering an area of 200- 300 feet from an antenna .