 Computers in communications  Advantages of using networks  Network scale  Network architecture  Network topology  Ethernet and Bluetooth

1. Communication & Networks
Part - 1
MR. RAJASEKAR RAMALINGAM
LECTURER – DEPARTMENT OF INFORMATION TECHNOLOGY,
COLLEGE OF APPLIED SCIENCES – SUR,
SULTANATE OF OMAN.

2. In this lecture…
 Computers in communications
 Advantages of using networks
 Network scale
 Network architecture
 Network topology
 Ethernet and Bluetooth
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3. Computer communications
 Home
 Office
 School
 Café
 Wireless hotspot
 Anywhere!
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4. Communicating
 Sender
 Medium
 Wired
 Wireless
 Receiver
 More than talk
 More than text
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5. Networks
 "Collection of computers and devices
connected together using communication
devices and transmission media“
 Any device connected to a network (wired or
wireless) is called a node
 The next slide has a diagram from the text
showing advantages of using networks
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6. 6

7. Network Scale
 LAN
 Local Area Network
 An office, a floor, a university
 MAN
 Metropolitan Area Network
 City-wide
 Often connects LANS
 London Fire Service
 WAN
 Wide Area Network
 Country, Region, World
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8. Network Architecture
Client-Server
 One or more servers
 Controls & coordinates access to network resources
 Hardware, software, data - "The Boss"
 Provides centralised, shared storage
 For software
 For data
 Uses network operating system
 May be specialised e.g. file server, print server
 Clients use network resources
 The worker's PCs
 Each computer is "equal"
 Every computer can share data and/or hardware
 Every computer is both a "server" and a "client"
 About 10 computers is the sensible limit
 Simple, easy, cheap
 Internet P2P
 A file sharing network
 Users connect direct to each other's hard disks and exchange files directly
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9. Client-Server
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In this example the server is also a print server

10. P2P
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Network operating system and application software on each
computer

11. Network topology
 The layout of the network
 Bus network
 Nodes connected to a single central cable (the bus)
 Inexpensive, easy to install
 Easy to connect/disconnect nodes without disruption
 Problems if the bus fails!
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12. Ring network
 Cable forms a closed loop
 Data moves in one direction around the loop, from one node to the
next
 If a node fails, nodes after that won't work
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13. Star network
 All nodes connected to a central device
 Uses a hub
 Easy to install and maintain
 Easy to connect/disconnect nodes
 If the hub fails…
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14. Hub
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Small (4 ports) to large (24+
port)

15. Most networks use a mixture of
topologies
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16. Topology summary
Advantage Disadvantage
Bus Easy to add/remove nodes
Node failure doesn't disrupt
network
If bus fails, network is disabled
Ring Larger distance than bus
topography
More difficult to install
Node failure disables all subsequent
nodes
Adding/removing a node disrupts
network
Star Easy to install and maintain
Easy to add/remove nodes
If hub fails, network is disabled
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17. Communication standards
 Allow different devices to "talk" to each other
 Example - PC, Apple, mobile phone
 Allow different networks to "talk" to each other
 Example - LAN, WAN, wired and wireless
 A standard that outlines how network devices
communicate is called a protocol
 The language that is used to communicate
 Examples include TCP/IP (in OMINT103), Ethernet
and Bluetooth
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18. Ethernet
 A networking standard
 Based on bus topology, but also used for star
 Specifies physical configuration
 Cabling, network cards, nodes etc
 Popular - inexpensive, relatively easy to maintain
 Often uses cable as transmission media
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19. Bluetooth
 A network protocol
 Defines how Bluetooth devices use short-range radio
devices to transmit data
 Speeds up to 2 Mbps
 Over distances of up to 10m
 Devices require a built-in Bluetooth chip, or a plug-in
Bluetooth adapter
 Examples - wireless mouse, sync PC and mobile
phone, phone and headset.
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