Chapter 2 : Communication and Internet Technologies
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how is data broken up before transmission and why?
Broken up into data packets. The packets of data are usually small, typically 64 KiB. Pros: much easier to control than a long continuous stream of data Cons: need to reassemble the data when it reaches its destination
What is the structure of data packets?
• a packet header • the payload • a trailer.
What is packet switching and the role of the router in the process?
Packet switching is a method of data transmission in which a message is broken up into a number of packets, each packet is sent independently from start to end. At each stage in the transmission, there are nodes that contain a router. Each router will determine which route the packet needs to take, in order to reach its destination
What is simplex data transmission?
Simplex mode occurs when data can be sent in ONE DIRECTION ONLY, ie. computer to printer
What is half-duplex data transmission?
when data is sent in BOTH DIRECTIONS but NOT AT THE SAME TIME Example: walkie talkie
What is full-duplex data transmission?
data can be sent in BOTH DIRECTIONS AT THE SAME TIME, ie. broadband internet connection
What is a USB?
Universal Serial Bus
What is serial data transmission?
when data is sent ONE BIT AT A TIME over a SINGLE WIRE/CHANNEL. Example: Connecting a computer to a printer via USB connection
What is parallel data transmission?
SEVERAL BITS OF DATA (usually one byte) are sent down SEVERAL CHANNELS/WIRES Example: internal circuits in a computer, because the distance traveled is short and high-speed is essential A phone is an example of parallel data transmission.
What are the benefits and drawbacks of USB systems?
Advantages disadvantages small compact low storage capacity Fast read-write over USB 3
Advantages and Disadvantages of the hard drive disc(hdd
Advantages cheap per MB storage Fast read-write speed large storage capacity Disadvantages has moving parts magnets can corrupt data
advantages and disadvantages of CD
Advantages cheap easily produced Disadvantages low storage capacity fragile
DVD
Advantages higher storage than CD universal format disadvantages still fragile
Blueray
Advantages Cheap highest storage disadvantages Fragile Quickly overtaken by streaming media
what is the difference between cd/dvd cd-r/dvd-r and cd-rw/dvd-rw
when it has a -r at the end it is an empty disc which you can put data on once when it has -rw at the end it is a disc on which you can put data on multiple times
What is a payload?
the actual data being sent in the packet
What is a trailer?
• method of identifying the end of the packet • Some form of error checking to ensure packet arrives error-free