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Data Transmission and Communication Networks (Describe simplex, half…
Data Transmission and Communication Networks
Describe serial and parallel transmission, their advantages and disadvantages
Parallel
transmission - it is where
all bits in a byte (8/16) are sent simultaneously alone separate data lines.
It is used internally when data is sent along buses.
Advantage
: it is
faster
than
serial
transmission.
Disadvantages
: requires 8/16
wires
; can only be used for
short distances.
Serial
transmission - it is where
data is sent bit-by-bit along the same data line.
Advantages
: can travel for
longer distances
than
parallel
; requires
only 2 wires
compared to 8/16.
Disadvantage
: it is
slow
and generally not as fast as parallel - with the
exception on fibre-optics.
Describe simplex, half duplex and full duplex transmission methods
Simplex
: where
data transmission is possible in one direction only.
An example would be sending sound to speakers - no feedback is required.
Half-duplex
:
where data transmission is possible in both directions, however, only in one direction at a time.
An example would be walkie talkies, two people can speak to each other but not simultaneously.
Full-duplex
: where
data transmission is possible in both directions, simultaneously.
An example would be video conferencing, video and sound transmitted to all at the same time.
Explain the need for multiplexing and switching
Multiplexing
: where
several independent data sources are combined to be sent along a single route to a specific destination.
Main advantage is that
transmission speeds can be increased.
Switching
: the
process of exaiming packets and routing data to a specific destination.
A switch connects segments of a network together.
Advantage
: requires
less bandwidth
to only send data where it
needs to go.
Describe, using appropriate network protocols, such as TCP/IP, the typical contents of a packet
Packet-switching
Data is
split into packets
, each one containing a
destination address
. The packets are then
analysed by each node
and sent down the
most appropriate path
to its destination.It is sent down the path that will be the
lowest cost
and
lowest traffic
. Each
node
maintains a
routing table
and on arrival, packets are
reassembled.
Contents of a TCP/IP Packet
Data
itself
Packet number
- allows packets to be
assembled
in right order.
Tracking information
-
route
taken can be
traced
.
Destination
address -
route
to destination.
Checksum
- checking of data for
errors
.
Source
address -
trace sender.
Explain network collision, network collision detection and how these collisions are dealt with
Data collision
:
occurs when two sets of data are transmitted on the network simultaneously.
The network then
detects the error
and each computer waits a
random amount of time
then
re-tries sending
the packet.
Example of a data collision within a bus topology:
https://drive.google.com/file/d/1qgCXSvPFm6K8bqrePvThJl_YW2wZTa6P/view?usp=sharing
Describe methods of routing traffic on a network
Router
: a
device in a network which holds the addresses of the computers on the network...
Routing
: ...
and can therefore send data to the correct computer.
Different types of routing
Static
: Each
router has access to a table
which tells it the
correct path
to use for each
destination address.
Advantage: Simple to implement.
Disadvantage: unsuitable for networks which frequently have new devices added to it.
Dynamic
: routers
learn the locations
of other devices based on
monitoring source and destination addresses
of data being
forwarded
.
Advantage: network changes would be automatically identified by the router, not requiring human interaction.
Disadvantage: network changes may not be immediate.