Data Transmission

Front 1

Serial

Back 1

Data is sent 1 bit at a time down a single connection

Front 2

Parallel

Back 2

Data is sent several bits at a time down a number of connectors

Front 3

Comparison of serial - parallel

Back 3

All other things being equal parallel will be faster but require more complex(expensive) cables

Front 4

Simplex

Back 4

Data can only travel in one direction(compare to broadcast radio)

Front 5

Half duplex

Back 5

Data can travel in both directions, but not at the same time(compare to intercom)

Front 6

Full duplex

Back 6

Data can travel in both ways at the same time(compare to phone)

Front 7

Circuit switching

Back 7

A route is negotiated. The bandwidth on the route is guaranteed. The data is sent all following the same path. The connection is closed.

Front 8

packet switching

Back 8

Data is broken into packets. Each packets contains the data a source and destination address, check sum and packet number. Each packet is individually routed through the network. At the receiver packets are put back into order

Front 9

Comparison of circuit and packet switching

Back 9

Circuit switching has guaranteed arrival time.
Packet switching is more fault tolerant, packets can find alternative routes.
Packets switching can make better use of busy networks.

Front 10

Data collisions

Back 10

Collisions occur when two packets are sent at the same time.
Each network card listens to the data packets it sends and identifies interference.
If a collision happens transmission is halted, after a random delay is resent.

Front 11

Router

Back 11

A router is a device in a network which holds information about the address of computers in the network.

Front 12

Protocol

Back 12

An agreement between two or more devices about how they should communicate.
Devices must agree on a protocol before data can be exchanged.
Standard protocols such as TCP/IP make it easier to connect devices together.

Front 13

Internet

Back 13

A network of networks. Connected using TCP/IP protocol