Transcript Internet - Knowledge on Line
Network of Networks Nobody owns it OS - No constraint TCP/IP Protocol VPN (Virtual Private Network) ISP INTRANET
Computer
Telephone MODEM Account with ISP Browser Inclination
COORDINATING GROUPS OF INTERNET Internet Engineering Task Force (IETF) – Operation, Management, Evaluation & development of protocols Internet Research Task Force (IRTF) – Long term research problems and technical issues
COORDINATING GROUPS OF INTERNET
Internet Architecture Board (IAB) – Overlooks the functioning of IETF & IRTF and ratifies their proposals Internet Society – Parent of IAB looks after overall promotion and usage of Internet in education, technical applications & new applications
INTERNET CONNECTIVITY
DIAL-UP : For single intermittent user; uses normal telephone lines with a modem.
ON DEMAND : Mid range option; Like a dedicated connection but user has to dial through a modem or ISDN (64-128 kbps). ISDN allows both voice & data.
INTERNET CONNECTIVITY
DEDICATED : For high volume use when No of users wish to simultaneously access Internet. Requires a router at the user end also. Option at different speeds are available.
SATELLITE LINK RADIO LINK ISP to INTERNET – T1 (1.544 Mbps) or T3 (45 Mbps) INTERNET BACKBONE – 1000 Mbps
DEDICATED CONNECTION - OPTIONS
Speed Type of Circuit Line No of Approx Users
INTERNET BACKBONE Year Speed
Very slow Speed Slow Speed High Speed Very High Speed 9.6 kbps Ordinary Tele line 64 kbps 1.544 mbps 45 mbps 12 64 kbps digital T1 digital T3 digital 40 1000 1,00,000 1969 1985 1987 1989 1999 Till date 9.6 kbps 56 kbps 1.544 mbps 45 mbps 155-1000 mbps
Internet Backbone R BASIC STRUCTURE OF INTERNET R R R R LAN Network Operation Centre R R R LAN Gateway LAN III PC LAN I LAN II Router Server PC PC PC Stand Alone PC
TERMINOLOGY OF INTERNET BRIDGE
– Connecting two NW operating with same OS
ROUTER
- Connecting two NW operating with different OS
BROUTER
– Plays both the roles of Bridge & Router
ISP
– Connects End-users to Internet backbone
GATEWAY
– A computer between ISP and Internet Router which connects the regional networks to Internet
INTERNET BACKBONE
– High bandwidth fiber optic line with numbers of routers End User End User ISP ISP Gate way Gate way Router
DOMAIN NAME SYSTEM
General Format – Host Name . Second Level Domain Name . First Level Domain Name Host Name – Service Provider Name Domain Name – Kind of Organisation Examples of Organisational & Geographic Domains gov – Government Agencies mil – Military site com – Commercial organisation net – Sites performing admin function org – Non profit organisation in – India us – USA
INTERNET ACCOUNTS
For joining Internet community registration with ISP is required.
Following type of accounts are available : Dial-up Shell Account SLIP or PPP Account On Demand connection/account Leased line
TECHNOLOGY BEHIND WEB
1.
URL : It is networked extension of standard file name concept. The file and its directory can exist on any computer on the network. Format of URL Protocol://DomainName/Directory/Sub-dir/file 2.
3.
http://www.yahoo.com/abc/homepage.html
HTTP : Request – Response Actions of HTTP (a) Browser uses HTTP commands to commn with HTTP server through a response provided by URL.
(b) A TCP/IP connection is established from client to the server.
(c) Browser sends a request to server typically for a file.
(d) Server sends a response message with the requested data.
(e) Connection is terminated after passing the message.
HTML : It is based on international electronic document standard called Standard Generalised Markup Language (SGML). Common basic language of interchange for hypertext documents. Doc creation by using control codes in ASCII to designate titles, headings, graphics & hypertext links. Doc size is small.
WWW
Originally developed in Switzerland Internet Navigator tool to retrieve information using links
Clients can display pages from any of ~ 5000 Web servers.
Has ability to incorporate FTP (File Transfer Protocol
Once a document is retrieved link with WWW is broken
Web page is truly MULTIMEDIA
FILE PROTOCOL TRANSFER SHAREWARE. S/W AVAILABLE ON TRIAL BASIS.
FREEWARE.
FREE S/W eg FONTS,CLIP ART & GAME.
UPGRADES.
UPDATES & FIXES OF S/W.
DOCUMENTS. RESEARCH PAPERS, ARTICLES etc.
IT CARRIESOUT SEARCH IN DIFFERENT WAYS AND COME OUT WITH DIFFERENT RESULTS. EACH SEARCH ENGINE HAS ITS OWN DATA BASE.
IT SENDS THE ELCTRONIC CRAWLERS (CALLED SPIDERS, WORMS OR ROBOTS) THROUGH WEB LOOKING FOR PAGES TO ADD TO THEIR DATABASE WEB PAGES. IT THEN ADDS OF EXISTING THE NEW ENTRY TO THE DATABASE .
SEARCH ENGINES Site Name Alta Vista Infoseek Look Smart Lycos Yahoo Northern Light Web Crawler URL altavista.digital.com
www.infoseek.com
www.looksmart.com
www.lycos.com
www.yahoo.com
www.northernlight.com
www.webcrawler.com
USER AGENT IN HML TEXT AND ARE WEB PAGES.
WEB BROWSERS
• • • •
INTERNET EXPLORER NETSCAPE NAVIGATOR NEOPLANET LYNX (TEXT ONLY)
• •
BROWSERS CAN READ & DISPLAY AS: HTML FILE EMBEDDED GRAPHIC IMAGES
User SubDm Domain Group Country
DOMAIN NAME SYSTEM
Distributed Hierarchical Naming System Name is given by traversing the tree to its root At each node a name is added and period (.) is appended Each node can have any number child nodes but only one parent node Each child node MUST have different name
com yahoo in net
Web Page Address
WWW.Yahoo.com
nic ap mil gov edu
E-mail Address
HOST COMPUTERS ON THE INTERNET
7000000 6000000 5000000
NUMBER OF USERS
4000000 3000000 2000000 1000000 0 1985 1986 1987 1991 YEAR 1992 1993 1994 1999