Transcript Standards and Technologies

BTEC IT Unit 09 - Lesson 03
Standards and Technologies
Mr C Johnston
ICT Teacher
www.computechedu.co.uk
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What is a standard?
Why do we need them?
Is there really a need for different technologies?
Session Objectives
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Be able to describe different standards and technologies which
are used to enable communication on a network,
Be able to determine which standards and technologies are
suitable for different types of a network.
Network Models
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The ISO OSI (open systems interconnection) model describes logically
how different devices communicate with one another,
As long as the standards are adhered to should not matter
what platform or device you are using – communication
should happen,
OSI model has 7 layers each representing a different part of
the communication process.
OSI Model
Application
Application
Presentation
Presentation
Session
Session
Transport
Transport
Network
Network
Data Link
Data Link
Physical
Physical
TCP/IP Model
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The TCP/IP (transport control protocol / internet protocol)
cuts the 7 layers of the OSI model down to 4,
The protocol allows data packets to be routed and allows
intercommunication between LANs and WANs,
All communication on the internet makes use of the TCP/IP
protocol.
Application
Application
Transport
Transport
Network
Network
Link
Link
File Sending Using TCP-IP Model
FileName.exe
Ethernet
Header
TCP Header
Part of
FileName.exe
TCP Header
IP Header
TCP Header
Part of
FileName.exe
IP Header
IP
Header
TCP Header
Part of
FileName.exe
Ethernet
Header
Part of
FileName.exe
TCP Header
IP
Header
Communication Medium
Part of
FileName.exe
TCP Header
Part of
FileName.exe
LAN Standards
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In order for commination to take place successfully the IEEE
(institute of electrical and electronic engineers) have defined
some standards for LANs.
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IEEE 802.2 – Logical Link Layer Control (LLC)
IEEE 802.3 – Ethernet inc MAC Addressing
IEEE 802.5 – Token Ring
FDDI – Fibre-Distributed Data Interface
Network Access Methods
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For a device to send data on a network you need to find an
available time slice,
Token ring networks operate in a “pass the parcel” fashion
where each machine waits its turn until the token is free,
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Problem though with big talkers!!!
Ethernet is better as devices send data when they want –
however can lead to collisions (device 1 and 2 send data to
each other at the same time).
Collisions
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A collisions on a network is where two devices try to sent
data to each other at the same time....
To overcome collisions Ethernet uses CSMA/CD (carrier sense
multiple access / collision detection) known as the “back off algorithm” to
help prevent reoccurring collisions,
A similar algorithm CSMA/CA (carrier sense multiple access / collision
aviodance) is used on wireless networks which detects signals
before data is sent to help prevent collisions.
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BTEC Book – Unit 09 p810
BTEC Book – Unit 10 p1719
BTEC Book – Unit 09 p810
Wireless Standards
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There are also a number of different standards for wireless
communication – WiFi
Most stem from the 802.11 standard including:
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IEEE
IEEE
IEEE
IEEE
802.11b
802.11g
802.11n
802.11ac
LANs are not the only type of network with wireless capability
other wireless technologies you need to know about include:
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Bluetooth – and its different classes
Infrared
3G / 4G
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BTEC Book – Unit 09 p810
BTEC Book – Unit 10 p1719
BTEC Book – Unit 09 p810
WAN Technologies
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Connection type
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DSL (digital subscriber line), ADSL
broadband
WAN structures
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Frame Relay, ATM
switching)
(asymmetric digital subscriber line),
(asynchronous transfer mode),
MPLS
Cable
(multi-protocol labelled
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BTEC Book – Unit 09 p4-6
BTEC Book – Unit 10 p4/5
BTEC Book – Unit 10 p14,15,16
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What is a standard?
Why do we need them?
Is there really a need for different technologies?