1. Transmission media

2. Transmission media Wired Co-axial Twisted pair UTP/STP Optical fibre
Telephone
UTP
STP
UTP/STP
Optical fibre
Wireless
Infrared
Laser
Microwave transmissions
point to point &
WiFi
Cellular radio

3. Co-axial cable Single conductor Outside shield
Good protection against interference
Fiddly to install
Used in bus-wired networks e.g. 10Base2
Used in Cable TV networks (see below)

4. Coaxial installation
To correctly install coaxial cable, the individual layers need to be accurately trimmed to correct lengths to match the connector.
Should use special crimp tool to attach the connector

5. Twisted pair cable
UTP
FTP
STP
Categories

6. UTP No outside shield Twists guard against interference
Cheap & easy to install
Standard in US & UK for data networks
Cat 5e / Cat 6

7. Office 1
Office 2
PC with NIC
PC with NIC
UTP or STP cable
(Up to 90m)
Equipment Room
Patch panel
Switch
Router

8. Up to 16Mbps e.g. Ethernet 10BaseT Cat 4 Up to 20MHz Cat 5
Cat No
Recognised by TIA/EIA?
Usage
Cat 1 No
POTS, ISDN, doorbells!
Cat 2
Token Ring 4Mbps
Cat 3
Yes
Up to 16Mbps e.g. Ethernet 10BaseT
Cat 4
Up to 20MHz
Cat 5
Up to 100MHz
Cat 5e
Up to 100MHz e.g. 100BaseT & Gigabit Ethernet
Cat 6
Up to 250Mhz
Cat 6a ?
Future spec for 10 Gbit/s
Cat 7
Up to 600MHz using STP cable

9. STP / FTP True STP has shield round each pair + overall shield
Difficult installation
Very good against interference IF well installed
FTP has standard UTP plus outside foil shield

10. Cable TV Cable TV companies use co-axial link to customer premises
Many use siamese cable (1 co-ax and 2 or more pairs of telephony cable)
Cable modem gives high speed connection
Limited geographical availability

11. Fibre-optic Problems with copper cabling UTP limit is 90m
Copper cabling not to be used outside buildings
Copper can be subject to interference
Fibre optic cable overcomes these problems
Note US spelling is FIBER

12. Fibre optic cabling
Reaches further (typically 285m in structured cabling network)
Has high bandwidth
Is immune to EMI
Is safe to run outside buildings
BUT is also
More difficult to install
More expensive
Fragile

13. How fibre works Glass cable
Two densities creates a barrier which reflects light.
Multimode 62.5 /125 i.e. Core=62.5 microns / Cladding=125 microns
A micron is 1/1,000,000 of a metre or 1/1,000 of a millimeter!

14. Multimode v. Single mode

15. Multimode v. Singlemode
Easier to install
Cheaper transmission equipment -> LED
But shorter distance -> Up to 285m in LAN
Singlemode
More difficult to install
More expensive transmission equipment -> Laser
Longer distance -> 10s of km

16. Connecting fibre
Ends of fibre core must be placed very close or touching
Light jumps from one fibre to the other
Alternative is fusion splicing – difficult & needs expensive equipment

17. Connecting fibre

18. Fibre connectors
ST connector
Bayonet locking
SC connector

20. Infrared Uses invisible light beam to connect Requires line of sight
e.g. remote controls
Used to be commonly used on laptops
Now being replaced by Bluetooth which doesn’t need line of sight

21. Laser Very high speed connection Requires line of sight
Relatively short range i.e. up to 4km
Susceptible to adverse weather (e.g. rain, snow, cloud, mist…)

22. Microwave Very high frequency radio beam Requires direct line of sight
Can bridge long distances e.g. up to 100km
Relatively resilient to adverse weather conditions

24. Radio Strictly speaking still microwave Line of sight NOT required
WiFi (IEEE ) for LAN use
WiMAX (IEEE )
Up to 50km (31 mile) range
Suitable for MAN use

25. Fixed Wireless Networking Standards
Institute of Electrical and Electronics Engineers (IEEE)
Mbps ** Obsolete **
a 54Mbps in regulated 5GHz range
b 11Mbps in unregulated 2.4GHz range g 54Mbps in unregulated 2.4GHz range (Backwards compatible with b) Many manufacturers offer products with a “Turbo” mode
2008? n 2nd draft issued Jan Testing to draft standard from early Ratification Nov 2008?

26. Benefits / Drawbacks of Wireless
Aesthetics
No unsightly wires
Lower installation cost
No faceplates
No cable
No labour
Good for places where cable not possible
Drawbacks
Lower bandwidth
Reliability issues
Connectivity
Interference
Higher equipment cost
Limited range
Security -> WEP
WEP Wired Equivalent Privacy (128bit encryption) Datalink (layer2) so all data sent gets encrypted

27. Satellite Line of sight (to satellite) required Good coverage
Propagation delay
Cost!!!

28. Cellular radio Historically only option for true mobile networking
To date very low speed compared to other LAN / WAN technologies e.g.
GSM 9600 bps (not Kbps or Mbps!!)
GPRS up to 56Kbps i.e. PSTN dial-up speed
New 3G networks offer much faster speeds
e.g. Vodafone HSDPA service up to 1.8Mbps
BUT
Cost
Coverage