Internet: An Overview

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Internet An Overview
Gopi Krishna S Garge ERNET Dept. of Electrical
Communication Engg. Indian Institute of Science
Bangalore 560012 gopi_at_ece.iisc.ernet.in
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The Internet

• A Logical, Global Meta Network of computer
  networks
• A physical maze and a functional wonder
• A virtual information store
• A comprehensive communication infrastructure
• A global arena for the hacktics''
• The BEST instance of a cooperative movement
• From the Idiot Box'' to Notebook''

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Terminology

• Link The physical media interconnecting various
  nodes of a network.
• Protocol The set of guidelines for host to host
  communication on the network software
  implementations.
• Internet Domain A logical grouping of computers
  on the Internet. The top level domain'' is a
  two character country code, the starting point of
  a domain hierarchy in a country. Eg
  fungi.biocon.co.in

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Terminology

• Internet Address A four byte network addressing
  scheme used by the IP layer, expressed in a
  dotted decimal form. Eg 202.41.127.5
• Internet Node A computer providing Internet
  access and supporting basic Internet Services.
• Servers Computers identified/dedicated to
  perform a specific Internet function. Eg Mail
  Servers, Name Servers, ftp Servers, WEB Servers
  .....

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A Functional Model
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Internet Domain
The .in domain has several subdomains (a.k.a
second level domains)

• gov.in
• mil.in
• net.in
• org.in
• res.in

• ernet.in
• nic.in
• uunet.in
• ac.in
• co.in

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Internet Domain
The top level domains in the world are

• .com
• .edu
• .gov

• .int
• .mil
• .org

Every country has a unique two character country
code (ISO 3166) for its Top Level Domain
singnet.com.sg
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Applying for an Internet Domain
To apply for an Internet domain, Contact

• Your local Service Provider
• Your Country's Network Information Centre
• http//www.apnic.net/
• The InterNIC
• http//www.internic.net/

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Applying for an Internet Domain

• domainreg_at_sangam.ncst.ernet.in
• OR
• Domain Registrar
• National Center for Software Technology
• 8th Floor, Air India Building
• Nariman Point
• Bombay 400 021
• Telephone [phone]
• Fax [phone]

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Services on the Internet
USER
User Services
Network Services
Registration Services
Name Services
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Services on the Internet

• Network Services
• Registration Services User/ISP's Registration
  Information
• Name Services Domain Name to IP address mapping
  
• User Services
• Electronic Mail
• File Transfers
• Remote Terminal Access (remote login)
• Remote Computing
• Remote Information Access (Databases, Infobases,
  Document Archives etc.)

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User Services

• There are a variety of user services available on
  the Internet some Internet wide and some within
  a specific user community
• Popular Services are largely email based or Web
  based
• Mailing Lists (List servers, Newsgroups ...)
• Access to Document/Software Archives
• Most of these archives provide for a mail based
  interface in addition to online access (ftpmail,
  infoservers, archiemail....)

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User Services

• OnLine'' access is the current trend
• Wide Area Information Servers (WAIS)
• Directory Services (LDAP)
• Archie
• Gopher
• World Wide Web

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That's not all ...

• Multimedia Services (Audio, Video and Data) are
  on the rise !
• Multimedia Support on Desk Top / Lap Top Machines
  
• Bandwidth Availability
• Bandwidth requirement on the WAN
• Technology to utilise Bandwidth

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So, What do you need ?

• Hardware
• A Pentium based machine with
• SVGA Monitor 14/17/19'' display card
• 32 Mb RAM
• 8 GB HDD
• 1 High Speed Serial Port (38.4 115 Kbps)
• 1 Network Interface Card
• 1 V.90/MNP 6 Sync/Async, Dialup/24W Leased Line
  Modem
• 1 TCP/IP Router with 1 LAN and 1 WAN interface

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So, What do you need ?

• Software
• Operating System
• MSDOSMSWIN 3.11/WFW OR WIN95/98/2000/NT OR
• UNIX X Windows
• Communication Software
• TCP/IP
• Line IP (SLIP) Support Dialup
• PointtoPoint Protocol (PPP) Support Dialup
• Terminal Emulation Software Dialup
• Application Software
• A Mail Client (/Server)
• A Web Browser (/Server)
• A ftp Client (/Server)
• A telnet Client (/Server)

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Connectivity Options
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Dial up Options
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Dial up Options
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Dial up Options
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Leased Line Options
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Protocol stack
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ISPs in India

• Seven Major ISPs in India
• Education Research NETwork ERNET (19881989)
• CUG, Network Interconnections Only, 9600 bps and
  above
• National Informatics Centre NETwork
  NICNET/RENNIC (1994)
• CUG, User Accounts NI, 1200 bps to 9600 bps
• Gateway Internet Access Services GIAS (1995)
• Public Network, User Accounts NI, 9600 bps to
  128 Kbps
• Department of Telecom DoT (1998)
• GIAS Franchisees
• MTNL (1998)
• Public Network, User Accounts, NI, 64 Kbps
• Satyam Online (1999)
• Public Network, User Accounts
• Mantra Online (1999)
• Public Network, User Accounts

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Information on the Internet

• The Internet, in the course of its evolution has
• A large number of rich information sources
• attempted to provide a usable'' interface to
  this information
• moved closer to the concept of a document''
• attempted to catalogue the information sources
• attempted to provide catalogue search interfaces

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Internet Stabilised ?

• The Internet is still evolving
• User Services are not fully standardised. A new
  utility every fortnight !
• Information Resources are made available largely
  on a voluntary basis.
• Access to resources not optimised
• No comprehensive Resource Index Resource
  discovery still through email !
• No guaranteed response times
• System and Data Security are still major issues

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The Future

• Technology
• ISDN will finally be used on a large scale
• The ATM Promise
• The Synchronous'' Advantage SONET, SDH
• Media
• Optic Fibre
• Unshielded / Shielded twisted pairs

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The Future...

• Services
• WEB Browsers (mosaic, Netscape) are here to stay
• Conferencing
• Value added services shopping, registration,
  reservations, validation .. .......
• Ongoing Efforts
• Internet access via cable TV networks
• Remote Seminars
• Adapting Internet services to the dialup user

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Proxy servers

• Proxy servers provide proxying services for
  network services to a user community
• Advantages
• Proxy server is the frontend all packets
  originate'' from the PS
• No direct'' access to outside resources
• Caching Support ! Fast turnaround times
• Private Addressing
• Optional Admission Control Support
• Configurable for all types of services
• Disadvantages
• Single point of failure
• Sufficiently large resources required

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Proxy servers
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Any question?

• ?