CIS105 Networking: Computer Connections
CIS105
Networking: Computer Connections
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.
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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!
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Initiates instruction
Converts data
Signal path
Converts data
ReceivesInstruction
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
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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)6
Physical Media
Wireless Generally slower Susceptible to interference Wi-Fi – Wireless Fidelity –
standard 802.11 MIMO (Multiple-in, Multiple-Out)
Infrared Bluetooth (see page 478) Cellular Radio
Microwave (line of site) Satellite – placed about
22,300 miles above 7
Wireless Media
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).
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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.
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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. 10
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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
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Ring Network
Star Network
Bus Network
Star 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 Easy to expand Many collisions – causes resend – Terminator’s located at
ends.13
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).14
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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.
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GateWay
Internet
Client computer requests services from server.
Server returns requested information / data.
Common uses include Web Server, Print Server, File Server, and Email Server.
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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.
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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
Want to learn more… CIS190 Introduction to LAN CNT140 Cisco Networking Basics MST150 Microsoft Windows Professional
HowStuffWorks-Firewalls
Review MCC’s Wireless Network: http://www.mc.maricopa.edu/its/net_services.html
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