2. Computer Network?
o âinterconnected collection of autonomous
computersâ
o What is the Internet?
â ânetwork of networksâ
â âcollection of networks interconnected by routersâ
â âa communication medium used by millionsâ
â Email, chat, Web âsurfingâ, streaming media
o Internet š
Web
oDistributed system
4. Why network?
Before networks:
â One large computer (mainframe) used for all
processing in businesses, universities, etc.
Smaller, cheaper computersâŚ
â Personal computers or workstations on desktops
â Interconnecting many smaller computers is
advantageous! Why?
5. Why network?
Resource sharing!
â Hardware: printers, disks, terminals, etc.
â Software: text processors, compilers, etc.
â Data.
Robustness
â Fault tolerance through redundancy
Load balancing
â Processing and data can be distributed over the network
Location independence
â Users can access their files, etc. from anywhere in the
network
6. Problems?
Security!
ďź Itâs much easier to protect centralized resources than
when they are distributed.
ďź Network itself as the target..
7. Applications
o WWW
o Instant Messaging (Internet chat, text messaging
on cellular phones)
o Peer-to-Peer
o Internet Phone
o Video-on-demand
o Distributed Games
o Remote Login (SSH client, Telnet)
o File Transfer
11. Home Network Applications
⢠Access to remote information
⢠Person-to-person communication
⢠Interactive entertainment
⢠Electronic commerce
16. The Wider Agenda
year
log (people per computer)
Number Crunching
Data Storage
Productivity
Interactive
Streaming
Information
to/from Physical
World
Mainframe
Minicomputer
Workstation
PC
Laptop
PDA
20. Computers of the Future
Computers are integrated
â small, cheap, portable, embedded
Technology is in the background
â computer are aware of their environment and adapt (âlocation awarenessâ)
â computer recognize the location of the user and react appropriately (e.g., call
forwarding, fax forwarding, âcontext awarenessâ)
Advances in technology
â more computing power in smaller devices
â flat, lightweight displays with low power consumption
â new user interfaces due to small dimensions
â more bandwidth
â multiple wireless interfaces: wireless LANs, wireless WANs, regional wireless
telecommunication networks etc. (âoverlay networksâ)
36. IEEE 802 Standards
The 802 working groups. The important ones are
marked with *. The ones marked with ď˘ are
hibernating. The one marked with â gave up.