software slides
TRANSCRIPT
Networks
Mr Arthur
Aims of Lesson 1
1. Introduce networks
2. LANs
3. WANS
4. Transmission Media
5. Client Server and Peer-to-peer networks
Stand Alone/Networked
A Stand Alone computer system is a computer that is not connected to any other
A network is a linked set of computer systems that are capable of sharing programs, data and sending messages
Local Area Networks
A LAN is a network of computers connected over a small geographical area, usually inside the 1 building
Examples School LAN Network in a library
Uses Sharing resources Sharing peripherals Email
Transmission Media Copper Wire, Fibre Optic and Wireless
Wide Area Networks
A WAN is a network of computers over a large geographical area, such as across a country or the world.
Examples The Internet Companies like the BBC communicating across the world
Uses video-conferencing, use of e-mail, live chat Sharing Information - access to databases, E-commerce and entertainment
Transmission Media Fibre Optic, Microwave transmission and Satellite
Client Server Network A client-server network is where all resources are stored
centrally on the server and are assessed by the client stations
Advantages Increased security as each user needs to log in Different levels of access are available Users can work on the same document at the same time Flexible uses of station, you can log on to a number of clients
and access your files Backup copies are completed centrally
Disadvantages If the file server is down there is no access to data More expensive as you need to buy a server and server
software
Peer to Peer Network
A peer-to-peer network is where each station has its own local storage device.
Advantages Easier to setup operating systems on stations in a peer-
to-peer Cheaper as no server is required
Disadvantages No central file storage – users must log in to the same
station to access files Users must backup their own data Peer-to-peer is less secure as users may not be required
to log in
Aims of Lesson 2
Last Lesson Introduce networks LANs WANS Transmission Media Client Server and
Peer-to-peer networks
Today’s Lesson
1. Network Topologies
2. Network Interface Cards
3. Hotspots
Star Topology
All peripheral nodes are connected to a central node
If a peripheral node fails it has no effect on the network
If the central node fails the whole network is “down” Advantage = Easy to add new
stations Disadvantage = Central node may
get congested with network traffic
Ring Topology
Signals are sent around the network from node to node
If a node is faulty, then there must be a method of bypassing the failed node
If a communications channel fails, the network fails
Bus Topology
The bus topology has each node connected to a main communication channel (The Bus)
If one node is faulty this has no effect on the rest of the network
If the bus is faulty, the whole network is “down” Advantage = Easy to add new stations Disadvantage = Each node may have to
compete with each other in order to transmit and receive data
Mesh Topology
A mesh topology has multiple direct connections between each node
The internet is an example of a Mesh network Advantage = A node failure
has no effect on the rest of the network
Disadvantage = Expensive to set up with a lot of cabling
Network Quiz
1. Give 3 functions of a LAN
2. Give 3 transmission media you would associate with a LAN
3. Describe a client server network (2)
4. Give 2 advantages of a client server over a peer to peer network
5. Describe a peer to peer network
Aims of Lesson 3
Last Lesson Introduce networks LANs WANS Transmission Media Client Server and
Peer-to-peer networks Network Topologies
Today’s Lesson
1. Network Interface Cards
2. Hotspots
3. Router
4. Hubs
Network Interface Cards
Network Interface Cards = a small printed circuit board inside the computer system allowing it to communicate with the network.
The NIC provides the computer with a unique Media Access Control (MAC) address made up of 6 bytes
Hotspots
An area where network signals may be received
Usually located in built up areas
May be deliberate hotspots in a University or may be accidentally created Warchalking Wardriving
Router A router is a device
which links 2 or more networks
The router takes packets of data and decides which route through the network the packet should take
HUBs
A hub is a device with multiple ports which allows more than 1 device to share the same wire
The hub will also boost or amplify signals
Multi-port repeater
Switch
A switch operates like a smart hub
The switch separates the network into segments
More than one machine can speak at once and only the intended recipients receives the signal
Aims of Lesson 4
Last Lesson Introduce networks LANs WANS Transmission Media Client Server and Peer-to-
peer networks Network Topologies Network Interface Cards Hotspots Router Hubs
Today’s Lesson1. Mainframes/Super
computers2. Current network trends3. Technical reasons for
increasing number of networks
Mainframes and Supercomputers
Mainframes A large powerful computer
which can process a very large amount of data at a high speed
May be connected to hundreds of dumb terminals
Multi-programming Multi-tasking Multi-processors
Supercomputers More powerful than a
Mainframe Supercomputers are used
for intensive mathematical calculations like weather forecasting, aerospace engineering
Current Network Trends
Higher Bandwidth Increasing amount of data carried
along communications channel Virgin Media advertising 20Mbps!!! There will be a limit however,
depending on the distance from subscriber and the telephone exchange
Wireless Functions WiFi, Bluetooth, Zigbee
Technical Reasons for Increasing Number of Networks
Advances in computer hardware Faster, Multiple processors Cheaper, higher capacity RAM chips Increasing Backing storage capacities Increasing data transfer rates
Improved Network software Browsers = improved functionality using
plug-ins, allowing streamed video, animated graphics to be displayed
Operating Systems designed with networking functions built in
Final Network LessonLast Lesson Introduce networks LANs WANS Transmission Media Client Server and Peer-to-peer
networks Network Topologies Network Interface Cards Hotspots Router Hubs Mainframes/Super computers Current network trends Technical reasons for
increasing number of networks
Today’s Lesson File, Print and Web servers Legislation
Computer Misuse Act Copyright Designs and
patents act Data Protection Act
File/Print/Web Servers
File Server A file server provides central disk
storage for user’s programs and data on the network
The file server will run 24 hours a day and must have a fast processor, lots of RAM and much larger hard disk capacity
Controls security on the network Backed up using a Digital Audio
Tape (DAT) Print Server
A print server will allow multiple clients share the same printer
The print server will use a spooler program and the printer will probably have a buffer as well
Web server A web server is a computer
that provides WWW services to a network
You have the benefit of “always on” fast access to pages
Every computer that host a website must have a web server program
Misuse of Networks
Copyright Designs and Patents Act This makes it illegal to copy music,
programs, movies etc without the permission of the owner
Computer Misuse Makes it illegal to hack or spread viruses
Data Protection Act Controls the storage of personal
information