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Data Communication Network (ch1) (Networks (<definition> (nodes…
Data Communication Network (ch1)
Data communication
<definition>
data
information presented in any form by the user and creator
<extra>data representation number,text,images,audio,vedio
data communication
exchange of data.
between 2 device.
through some form of transmission medium.
//example wire cable
extra
must be far apart
consist of hardware(physical equipment) and software(programs)
effectiveness depends on
delivery (correct destination)
accuracy (no alteration in data)
timeliness (the speed of transmission)
jitter (evenness, varition in packet)
telecommunication
included
telephony, telegraphy, television
<
tele
> in Greek means far
communication at a distance
Component
protocol
>> sets of rules
message
>>data to be commucated
transmission medium
>> a physical path message travels
sender
>> device that send the data
receiver
>> device receive the data
data flow
simplex
>> one way street. Entire capacity channel send in 1 direction. Example monitor.
half-duplex
>> both can send and receive but not same time. channels utiesed for each direction. Example walkie-talkies, radio
full-duplex
>> both can receive and transmit simultaneously. capacity of channels must be devided into 2 direction. Example telephone
Networks
<definition>
nodes
device that capable to send or recieve data
network
interconnection of a set of devices(nodes) connected by communication links
host
device or end system such as PC,phone
connecting device
connect the network to other network such as router
network criteria
performance
many ways to measure >> transit and respond time, throughput and delay<networking metrics>//usually contradictory
reliability
measures by frequency of failure
security
protect from unauthorized access,protect data
physical structure (network attributes)
type of connection
point-to-point
provide link between 2 devices
multipoint
also called mutidrop connection
more than 2 spesific device share same link
shared connection
partially shared connection
>> devices can use link at same time
timeshared connection
>> users must take turns
physical topology (way network laid out physically)
mesh topology
to know
each node connect to every other node
need n (n – 1) / 2 full duplex-mode links.
every device on the network must have n – 1 input/output (I/O) ports to connect to the other n – 1 stations.
every device dedicated point-to-point link to every other device
advantages
each link can carry each own load
robust. if 1 link unusable, others can still use
higher privacy and security because there is dedicated link
disadvantages
need massive amount of cabling
massive amount of space need to be allocated
costly
star topology
to know
each need only 1 link to connect to hub
advantages
less cabling
robust,as long as hub still working
disadvantages
dependency on single point(the hub)
every node need to connect to single hub
bus topology
to know
nodes are connected by bus cable by drop-line and taps
advantages
easy installation
disadvntages
difficult to add new device
one fault/ break can stop all transmission (any point brek cause noise reflected back to origin)
ring topology
to know
nodes are connected to ring cable by a repeater
each link is only connected to its neighbour
advantages
easier to add and delete device
isolation is simplified
disadvantages
unidirectional link can disable whole network if there is a fault
hybrid topology
network types
Local Area Network (LAN)
Wide Area Network (WAN)
point-to-point WAN
switched WAN
internetwork
switching
circuit-switched network
packet-switched network
the internet
accessing
telephone networks
dile-up service
DSL service
cable networks
wireless networks
direct connection to internet
history
early history
birth of internet
internet today
<definition>
standards and administration (protocols and standards)
internet standarts
<definition>
internet administeration
ISOC
IAB
IETF
IRTF