Internet - Lecture Slides, Slides of Web Application Development

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Internet

The Evolution of the internet

• The first network was ARPANET
• For the use of US defense
• Initially only a few universities and defense contractors were a part
• Got commercialized in 1990 due to the use of WWW.

A few concepts…

• Bandwidth… channel capacity
• Baseband transmission… single signal
• Broadband transmission…. Multiple signals using a variety of wired connections.
• Connection can be wired or wireless
• Data is transmitted in bps, kbps, mbps and gbps
• Uploading and downloading

Narrowband (dial-up modem)

• Low speed and inexpensive
• Low bandwidth
• Widely available
• Uses a telephone modem to connect to the internet
• A modem is a device that sends and receives data to and from the computers over the local telephone lines.
• It can be internal or external with speeds like 56 kbps
• Drawbacks:
  • Speed mismatch
  • Call waiting.
  • Traffic lineup.

• Cable modem
  • Connects to a cable TV system
  • Adv is that its always connected and doesn’t require a switching station nearby like DSL
  • A drawback is that is slows down at peak hrs and allows outside interference
  • It gives the user the choice to select the ISPs

Satellite Wireless connection

It helps you to connect to the internet without POTS.

It requires an unobstructed line of sight to connect through a satellite access hardware.

A pizza size dish is required that sends and receives microwaves to communicate.

For such communication an ISP is required that supports 2 way satellite communication.

3G

• Third generation is wireless connection to the internet. It is a high speed wireless connection that does not need access points because it uses the existing cellphone systems.
• It is used by cell phones and PDAs and handheld devices.

Internet Access Providers

• Internet Service Providers…regional or local or national organizations that provide access to the internet.
• Commercial Online Services…not only provide internet access but also other services like news, games financial data eg MSN
• Wireless Internet Service Providers…they provide internet access wirelessly to devices that contains wireless modem like laptops and handhelds.