1. Chapter 5 Networks Communicating and Sharing Resources

2. Chapter objectives: Understand basic networking.
Discuss the advantages and disadvantages of networks.
Distinguish between Peer-to-Peer & client/server LAN.
Define topology and understand how 3 LAN topologies differ.
Explain the importance of protocols.
Most widely used protocol & it’s versions.
Identify the special components of wide area network (WAN) that differentiate from LAN.

3. Network Definition
Set of technologies that connects computers to allow communication and collaboration between users.
A group of two or more computer systems linked together to exchange data.
Any device connect to the network referred to as a node.
Any device has a unique logical address (name).
Any device also has a unique physical address (MAC).
A node need NIC to connect to network.

4. The Uses of a Network Simultaneous access to data
Data files are shared
Shared files stored on a server
Software can be shared
Shared peripheral device
Printers and faxes are common shares
Reduces the cost per user
Devices can be connected to the network
Teaching Tip
Figure 9A.2 on page 342 visually describes the sharing process. It can be helpful to have students open a shared file that you control. Make a change then have the students open it again. Alternatively, share a document and allow your students to write in it. Then demonstrate how the shared document changes.
Spend time discussing why application servers need to be so powerful.

5. The Uses of a Network Personal communication Email Conferencing
Voice over IP
Phone communication over network wires
Easier data backup
Backup copies data to removable media
Server data backed up in one step
Teaching tip
It is fun if you can setup a teleconference in your classroom. Students get to learn how to join or create the conference. Additionally, they learn how to participate. Finally, students have fun, especially with shared whiteboards.

6. Sharing Data
File server contains documents used by other computers.

7. 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.

8. Common Network Types LAN Protocol:
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.
LANs Types
Wired LAN
Wireless LAN
VLAN
LAN Protocol:
Standard or Rules specify how two dissimilar network components can establish a communication.
Teaching tip
Use a real world example to describe an organization with interconnected LANs.

9. Wired LAN Network Cables Unshielded Twisted Pair (UTP) Cable
Shielded Twisted Pair (STP) Cable
Coaxial Cable
Fiber Optic Cable
Ethernet: the most popular cabling technology in LAN.
Ethernet uses
a protocol called
CSMA/CD
Twisted Pair cable
Coaxial cable
Fiber Optic cable
Rj-45 connector

10. Network Interface Card
Connects node to the media
Unique Machine Access Code (MAC)
Insider Information
The Xerox Corporation controls the assignment of Ethernet addresses to NIC manufacturers.

11. Wireless LANs Wifi standards and speeds
Wi-Fi: wireless LAN standard that offers Ethernet speeds through the use of radio waves instead of wires.
Wifi standards and speeds
Standard
Max Speed
Typical Range
802.11a
54 Mbps
150 feet
802.11b
11 Mbps
300 feet
802.11g
802.11n
100 Mbps
300+ feet

12. Network layers

13. Types Of (LAN)Structure
Types of LAN in terms of MEDIUM
Wireless
Wired
Types of LAN in terms of Networking Model
Peer-to-peer
Client/Server
Virtual private Network

14. Peer-to-Peer Network(P2P):
Tend to slow down as the number of users increase.
Keeping track of all the shared folders & files can be confusing.
Security not strong because the lack of hierarchy.
Nodes access resources on other nodes
Each node controls its own resources
Peer-to-Peer Network(P2P): All of the computers on the network are equals or peers and there is no file server but there is a file sharing in which each computer users decides which, if any, files will be accessible to other users on the network. Users also may choose to share entire directories or even disks, they can also choose to share peripherals such as printers. P2P networks are often used for home work or small business they don’t require a NOS (Network Operating System) and can be set with any operating system. P2P LAN are best used for simple networks connecting no more than 10 computers.

15. Client/Server network
Nodes and servers share data roles
Nodes are called clients
Servers are used to control access
Database software
Access to data controlled by server
Server is the most important computer
Virtual Private Network (VPN)
Operates a private network over the internet
Client / Server Network: Includes one or more servers as well as clients . A client can be any type of computer ---- PC, Mac, desktop, notebook or handheld device that is connected to a network and contains the software that enables it to send requests to server. It can work with any size or physical layout of LAN and doesn’t tend to slow down with heavy use.
Virtual Private Network (VPN): used by many business companies to provide their employees and customers with quick, secure access to the corporate information. A VPN operates a a private network over the internet making the data accessible to authorized users in remote locations through the use of secure, encrypted connection & software.

16. 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.

17. 1- Bus Topology

18. 1- Bus Topology One wire or cable connects all nodes.
Terminator special connectors ends 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.

19. 2- Star Topology

20. 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

21. 3- Ring Topology

22. 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.

23. Wide Area Networks (WAN)
Two or more LANs connected
Over a large geographic area
Typically use public or leased lines
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!

24. WAN PROTOCOLS
TCP/IP are open protocols that define how the Internet works.
IP defines the internet addressing scheme.
TCP defines how one computer can contact another to exchange control and confirmation messages.
Circuit switching
A protocol (method) used in a telephone systems with direct connection between the communicating devices.
Packet switching
A method used when no effort is made to create a single direct connection between the communicating devices.
The internet protocols collectively called TCP/IP
TCP/IP is an abbreviation for transmission control protocol(TCP)/internet protocol(IP)
IP is the most fundamental of all internet protocol because it defines the internet addressing scheme which enables any internet-connected computer to be uniquely identified.
IP address has for part which are separated by periods (such as )
Circuit and packet switching WAN protocols are based on either circuit-or packet switching network technology, but most use packet switching
packet switching is more efficient and less expensive than circuit switching
With Circuit switching the method used in the public switched telephone system there is a direct connection between the communicating devices
With packet switching the method used for computer communication no effect is made to create signal direct connection between the two communicating devices

25. Network Hardware Switches Hubs Replacement for hubs
Only intended node receives transmission
Fast and secure
Center of a star network
All nodes receive transmitted packets
Slow and insecure

26. Network Hardware Gateway Router Bridge
Connects two dissimilar networks
Connects coax to twisted pair
Most gateways contained in other devices
Connects two or more LANs Packets sent to remote LAN cross
Network is segmented by IP address
Connect internal networks to the Internet
Need configured before installation
Connects two or more LANs together
Packets sent to remote LAN cross ,other packets do not cross
Segments the network on MAC addresses