1. Unit 27: Principles of Computer Networks
Introduction to Networks
Network Types
BTEC Nat IT Business - Principles of Networking

2. Aims Different types of Networks revised
Understand the purpose of a computer network
Create network drawings
Understand Packets
BTEC Nat IT Business - Principles of Networking

3. What is the purpose of a network?
Enables file sharing (should cut down on printing costs)
Share resources, such as printers, scanners, etc., to get more use out of office equipment (cutting down costs)
Share software with multi-user licenses.
Perform data backups quicker and easier with files on shared drives.
Easier and more manageable Internet connection
BTEC Nat IT Business - Principles of Networking

4. Types of Network LAN (Local area network)
The definition of a LAN has become increasingly vague over the last ten years.
It was understood that it was interconnected computers at one location i.e. college or a workplace.
Know due to faster technology LAN devices can be used over longer distances.
A LAN can be as small as two computers by using a simple Ethernet connection or can divided into sub networks using switches and routers.
BTEC Nat IT Business - Principles of Networking

5. Local Area Network - LAN
Single campus
Can be multiple networks interconnected
No special telecommunications hardware is necessary, as cables/signals never leave the company’s premises
Fast data transfer rates
reliability of transmission not always top priority
damaged data can be re-transmitted easily
Video-conferencing is feasible

6. Task
Using Visio try to recreate the LAN shown below. (Feel free to make it your own)
BTEC Nat IT Business - Principles of Networking

7. Types of Network WAN (Wide area network)
A WAN is a complex network system, comprising of interconnected LANs.
WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations.
WANs are often built using leased lines. A router connects to the LAN on one side and a hub within the WAN on the other
Network protocols including TCP/IP deliver transport and addressing functions.
WANs are often built using leased lines. At each end of the leased line,.
Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs
WANs can also be built using less costly circuit switching or packet switching methods.
BTEC Nat IT Business - Principles of Networking

8. Wide Area Network - WAN The rest of the planet
Slower data transfer rates (end to end)
reliability is a high priority
retransmission of missing data is a large overhead
extensive use of external telecommunication systems
backbone transfer rate is now faster than LANs!
The Internet
International telecommunications
Satellite systems
e.g. Global Positioning System - GPS

9. Several options are available for WAN connectivity:
BTEC Nat IT Business - Principles of Networking

10. WAN
BTEC Nat IT Business - Principles of Networking

11. Janet backbone
All UK academic institutions access the internet via the Janet network
.ac.uk domain
Funded by Joint Information Systems Committee (JISC)
In October 2006 SuperJANET5 was launched after £29 million of investment.
It provided an upgrade path to 40GBit/s.
Most organisations connected by twenty WANs
Map from

12. WAN TECHNOLOGIES FRAME RELAY ATM – ASYNCHRONOUS TRANSFER MODE
MPLS – MULTI-PROTOCOL LABELLED SWITCHING
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13. FRAME RELAY PACKET SWITCHING MESH CONNECTIONS CORE OF A WAN
Monitors traffic on system – re-routing
Directs traffic from system to system
Cheap
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14. ATM Data cells smaller than packets Faster
Separate voice and data communications
Used with Skype
Similar functions to Frame Relay
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15. MPLS Most recent successor Cooperates with routing protocols
Highly adaptable
Adjusts to changes in networks
Directs data from one network node to another using short path labels not long network addresses
BTEC Nat IT Business - Principles of Networking

16. Types of Network MAN (Metropolitan area networks)
A Metropolitan Area Network (MAN) is a large computer network that spans a metropolitan area or campus. The network size falls intermediate between LANs and WANs.
MANs provide Internet connectivity for LANs in a metropolitan region, and connect them to wider area networks like the Internet.
They typically use wireless infrastructure or optical fiber (or fibre) connections to link their sites.
A MAN (like a WAN) is not generally owned by a single organisation. The MAN, its communications links and equipment are generally owned by either a consortium of users or by a network service provider who sells the service to the users.
BTEC Nat IT Business - Principles of Networking

17. Metropolitan Area Network - MAN
Multiple campuses
e.g. within a city
small geographical area
Australians use MANs to interconnect South Eastern cities
Slower data transfer rates?
need reliability of WANs with speed of LANs

18. VAN – Value Added Networks
Hosted sevice
Like a regional Post Office
Intermediatory between business partners sharing standards or data
Transmits data by EDI or as XML
Routes, stores & delivers EDI messages
EDI – Electronic Data Interchange – transfers electronic documents or business data from one partner system to another
BTEC Nat IT Business - Principles of Networking

19. PAN – Personal Area Netork
Interconnects devices in an individual person’s workspace
Wireless connections – Bluetooth
Can connect to a higher level network or Internet
Bluetooth – short range radio waves up to 10 metres
Computers, cell phones, PDAs, headsets, mouse or other pointing devices
BTEC Nat IT Business - Principles of Networking

20. Types of Network Mesh network
A netlike communications network in which there are at least two pathways to each node.
A fully meshed network means that every node has a direct connection to every other node. Most mesh networks are partially meshed and require traversing nodes to go from each node to every other.
BTEC Nat IT Business - Principles of Networking

21. Task Using the internet look into what a packet is.
Create a network diagram in Visio to represent “SuperJanet”.
BTEC Nat IT Business - Principles of Networking

22. Packet
A packet is a formatted unit of data carried by a packet mode computer network.
Computer communications links that do not support packets, such as traditional point-to-point telecommunications links, simply transmit data as a series of bytes, characters, or bits alone.
When data is formatted into packets, the bitrate of the communication medium can better be shared among users than if the network would have been circuit switched.
By using packet switched networking it is also harder to guarantee a lowest possible bitrate.
BTEC Nat IT Business - Principles of Networking

23. Conclusion Considered the purpose of a computer network
Revised some of the different types of networks
Used Visio to create network diagrams
Gained an understanding of a Packet
BTEC Nat IT Business - Principles of Networking