Computer Network :
- Set of serial lines to attach terminals to mainframe?
- Telephone network carrying voice traffic?
- Cable network to disseminate video signals?
What Distinguishes a Computer Network?
- Generality
- Built from general-purpose programmable hardware
- Supports a wide range of applications
Applications – Consumers of Networks:
- On a simple click, several messages may be exchanged over the Internet
- In a web browser, 17 messages may be exchanged
- up to six messages to translate the server name
- three messages to set up a TCP connection
- four messages to send HTTP “get” request + response
- four messages to tear down the TCP connection
- Moreover, millions of messages are exchanged each day by Internet nodes to make their presence and services known
Applications – the Driving Force:
- Streaming audio and video is an emerging application
- The source generates and sends the video stream in messages across the Internet
2. Video-on-demand: reads a preexisting movie
- One-way data transfer
3.Videoconferencing: interactive session
- Very tight timing constraints
4.Diversity of applications that can be built on top of the Internet hint at the complexity of the
Internet design
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