1. CIS105 Networking: Computer Connections

2. Topics Describe the basic components of a network.
Explain the methods of data transmission, including types of signals.
List communication equipment and channels options.
Describe various network topologies.
Define firewall and communication protocols.

3. Network
A Computer Network is two or more computers connected together with data communications equipment over a communications channel/media.
Benefits of Networks?
Reduce costs by sharing hardware, software, and data (information).
Communication!

4. Initiates instruction
Simple Network Model
Signal path
Converts data
Converts data
Initiates instruction
Receives
Instruction

5. Communication Equipment/Devices
Modem – modulate /demodulate
Converts digital signal to analog and vice versa
Telephone Dialup Modem (56 Kbps)
DSL (Digital Subscriber Line) modem
Cable Modems (cable companies)
Cellular Modem (uses cellular system)
Network Integrated w/ Motherboard
Network Interface Card (NIC)
Installed in expansion slot
Wired or wireless cards

6. Communication Channel / Media
Physical Media
Twisted Pair (TP) Cable
Shielded (STP)
Unshielded (UTP)
Ethernet uses RJ45
Telephone uses RJ11
RJ – Registered Jack
Coaxial Cable (coax)
Copper + 3 layers of insulation
Fiber Optic Cable
Glass/plastic – uses light to transmit
Speed of light
Tubes are insulated
Wireless (next slide)

7. Communication Channel / Media
Wireless Media
Wireless
Generally slower
Susceptible to interference
Wi-Fi – Wireless Fidelity – standard MIMO (Multiple-in, Multiple-Out)
Infrared
Bluetooth (see page 478)
Cellular Radio
Microwave (line of site)
Satellite – placed about 22,300 miles above

8. Transmission Characteristics
Bandwidth – is the measurement of how much information can be transmitted over a medium over a prescribed period of time.
Signal Type
Analog (continuous signal for older media).
Digital (individual electrical pulses - binary).
Broadband transmission– multiple signals simultaneously in both directions - shared line - (Internet connections).
Baseband transmission – one signal at a time.
Simplex – data is transmitted one direction only (TV).
Half-duplex – data is transmitted in both directions, but not at the same time (CB Radio, ATM, FAX).
Full-duplex – data is transmitted in both directions at the same time for same device (telephone, modem dial-up service).

9. Transmission Modes Asynchronous – start/stop signals for each message.
Message is usually one or two bytes long.
Low-speed communication
Synchronous – larger block of characters are transmitted together.
Includes error-check bits at the end of the message.
More complex and more expensive.

10. Local Area Network (LAN)
A LAN is a collection of computers connected together to share hardware, software, and data.
LAN Hardware
Network Interface Cards (NIC) for devices
Communications Channel / Media
Hub – connects computers to create a LAN
Bridges and Routers – connects LANS that use the same protocol
Gateways – connects LANS that use different protocols, and also serve as routers.

11. Communications Closet

12. Star Ring Bus See next slide
Star Network
Node - each computer, printer, or server on network
Network Topology is the physical layout of a network.
Three common topologies
Star
Ring
Bus
See next slide
Ring Network
Bus Network

13. Star – Ring - Bus Star Ring Bus
Server is in center with attached clients
If server goes down, network goes down
Easy to expand
Server controls collisions
Ring
All computers connected by a single line
If any computer goes down, the network goes down
Difficult to expand
No collisions, because token travels around one way
Bus
All nodes share a single line
If a computer goes down, the network is still up
Many collisions – causes resend – Terminator’s located at ends.

14. Wide Area Network (WAN)
Connecting two or more LAN’s of the same company.
Can link computers across town or span the world.
Common carriers are companies licensed by FCC to provide these services as leased lines.
Dedicated lines provides permanent connection between two or more locations
Companies can build their own (microwave, fiber, etc.)
T1 and T3 high-capacity digital lines can be leased
Digital Subscriber Line (DSL) use telephone lines
Connect with Router or Gateway
Will need a firewall to keep intruders out, which can be hardware and/or software (see next slide).

15. Firewall
Firewalls block unauthorized users from entering the network and unauthorized software from making outbound connections (spyware).
Windows includes personal Firewall protection.
Separate products can also be purchased.

16. WAN Model
GateWay
Internet

17. Client/Server Uses Client computer requests services from server.
Server returns requested information / data.
Common uses include Web Server, Print Server, File Server, and Server.

18. Peer-to-Peer Networks
Connect directly to another computer to create a LAN.
Need to activate Operating System features.
Server is not required.
All computers have equal status.
Users share each other’s files, printers, etc.
Common in small offices.

19. Communication Protocol
How is all of this communication possible?
Protocol - a set of rules for the exchange of data.
Agreement on how data is to be sent and receipt acknowledged.
Needed to allow computers from different vendors to communicate.
Common protocols include Ethernet, Wi-Fi, TCP/IP
Transmission Control Protocol/Internet Protocol (TCP/IP)
Permits any computer to communicate over the Internet.
Uses packet switching – original message is broken up; each piece has address of destination; each piece may take a different route; receiving computer puts all the pieces together.

20. Summary HowStuffWorks-Firewalls Want to learn more…
CIS190 Introduction to LAN
CNT140 Cisco Networking Basics
MST150 Microsoft Windows Professional
HowStuffWorks-Firewalls
Review MCC’s Wireless Network: