ITCS631 - #1

vasaka.vis@mahidol.ac.th
vasaka.vis@mahidol.edu
(ext. 118)

Definitions:
Data Communication: transmission digital data over a long distance
Communication Network: set of equipment and facilities that provide service and transfer information across distance.
A computer network: computers interconnected using a technology.

Pre-test:
unit of transmission rate: bps
1 byte = 8 bits
50 bytes = 400 bits

Client/Server (specific roles) vs Peer-to-peer (no fixed roles)
What is internet? = network of networks
Packet switching (ex. the internet) vs Circuit switching (need to make a confirmed call before the connection is established)
Protocol: define format, order of message sent and received, transmission...

DSL: use DSLAM (data for internet and voice for telephone), up 2.5 Mbps and down 24 Mbps

Cable network: 9 channels (6 for video, 2 for data and 1 for control)
Ethernet: today LAN technology
Shared (share speed among others) and Dedicated network (fixed speed)

end-to-end delay:
Satellite 270 msec & LAN 10 msec

Packet Delay = L, length of packet (bit) / R, transmission rate (bit/sec)

assuming zero propagation delay => end-to-end delay = 2L/R

router function: routing (determine path) and forwarding packets

FDM (divide medium equally) vs TDM
http://tdfdm.blogspot.com/