1. Chapter 6 Networks Communicating and Sharing Resources

2. Network concept
Network : A group of two or more computer systems linked together to exchange data.

3. Basic Network Concepts.
Any device connect to the network referred to as a node.
computer needs Network Interface card(NIC) to connect to network.

4. Communication devices

5. Basic Network Concepts
Router : is device or software that is used to Connects two or more network .
Determine the best path to route data and locate alternative pathways so that the data reaches its destination .
Switches: devices that filter and forward data between computers, printers, and other network nodes.
Switches are similar to routers but are used only to move data between nodes within a single network.
Server: computer that manages network resources like files, s, printers, and database.

6. Advantages and Disadvantages of Networking:
Reduce hardware costs.
Sharing application.
Sharing information resources.
Centralized data management.
Connecting people.
Disadvantages:
Loss of autonomy.
Lack of privacy.
Security Threats.
Loss of productivity.

7. Common Network Types WAN LAN
Teaching tip
Use a real world example to describe an organization with interconnected LANs.

8. 1.Local Area Network (LAN)
LAN interconnects devices in a limited area such as a home, school, or office building using network media.
Contains printers, servers and computers.
Systems are close to each other.
Organizations often have several LANS.
Teaching tip
Use a real world example to describe an organization with interconnected LANs.

9. 2.Wide Area Networks (WAN)
Two or more LANs connected
Over a large geographic area
Typically use
Phone lines
Satellite
The Internet is a WAN
Teaching tip
Blockbuster Video uses a WAN to connect it’s stores nationwide. Customers from Pittsburgh may rent videos in Hilton Head. Late fees will even be displayed!

10. LAN Topologies Network Topology: the physical layout of the LAN.
Bus Topology.
Star Topology.
Ring Topology.
* Topology isn’t just arrangement of computers but provides solutions to the problem of contention which occurs when 2 computers try to access the LAN at the same time.
*contention sometimes result into collisions which is the corruption of network data caused when 2 computers transmit simultaneously.

11. 1- Bus Topology

12. 1- Bus Topology One wire or cable connects all nodes.
Terminator special connectors ends of the circuit.
Advantages
Simple, reliable and easy to expand
Easy to setup
Small amount of wire
Disadvantages:
Only one node can transmit at a time.
Slow & Easy to crash
Used at home or small office.
If more than one node transmit at the same time each node waits a small random amount of time before it attempts to retransmit again.
Length restriction because of the lose of signal strength.
Practical limit to the number of nodes attached to avoid contention. To resolve contention problems bus network uses some type of contention management a technique that specifies what happens when a collision occurs.

13. 2- Star Topology

14. 2- Star Topology Solves the expansion problems of the bus topology.
All nodes connect to a hub
Packets sent to hub
Hub sends packet to destination
Advantages
Easy to setup and add users.
One cable can not crash network
Disadvantages
Loss of hub crash down the entire network
Uses lots of cable
Most common topology used at office buildings, computer labs and WAN.
* Hub: central wiring and simple broadcast device that does not manage traffic and usually results in frequent collision

15. 3- Ring Topology

16. 3- Ring Topology Nodes connected in a circle.
Not in common used today.
Special unit of data called Token travels around the ring and is used to transmit data
Nodes can transmit only when it posses the token.
Advantages
Time to send data is known
No data collisions
Disadvantages
Slow
Lots of cable
Well suited for use within a division of a company or on one floor of a multi floor building.

17. How to Protect Your Network
Use a firewall and an updated anti-virus software
Change the router’s default network name (SSID) and the default password.
Ensure your Router’s software has been upgraded to the most recent version.
Turn on WPA (wi-fi protected access) to enable encryption.
Turn on MAC (media access control) address filtering so only authorized devices can access
If you’re keeping a wired network secure with a firewall, you’re fairly safe from most hacker attacks. However, wireless networks have wide ranges, including areas outside of your house. This makes it possible for a hacker to access your network without your knowing it.
Most wireless network adapters are set up to access the strongest wireless network signal detected. Piggybacking is connecting to a wireless network (that is not your own) without the permission of the owner. This practice is illegal in many jurisdictions but often happens inadvertently between neighbors.
Because your packets of information are being broadcast through the airwaves, a hacker can intercept and decode information from your transmissions that might allow him or her to bypass your firewall.
Others might steal your bandwidth, and crimes can be committed through your network.

18. The End