NETWORK SYSTEMS 3.02 UNDERSTAND CONNECTIVITY THROUGH NETWORKS AND THE INTERNET
Mar 30, 2015
NETWORK SYSTEMS
3.02 UNDERSTAND CONNECTIVITY THROUGH NETWORKS AND THE INTERNET
COURSE CONTENT
GOALS
Definition• Provides a path for information to be sent from one computer to another through a network
Types of Transmission Media:•Coaxial cable•Ethernet cable•Fiber optic cable•Wireless transmission
TRANSMISSION MEDIA
Definition• Cable specifically designed for carrying an electronic signal
Features:
•Cable Length (200 – 500 meters)•Cost (Ethernet < Coaxial < Fiber Optic)•Ease of Installation (Moderately difficult to install)•Susceptible to EMI and RFI interference
• Consists of four layers of material to reduce interference
COAXIAL CABLE
Definition• Cable commonly used in high-speed wired computer networks
Features:•Cable Length (Up to 100 meters)•Cost (Ethernet is the cheapest)•Ease of Installation (Easy to install)•Susceptible to EMI and RFI interference
• Twisted pair wiring reduces interference•Types
• Straight-through• Crossover• Rollover
ETHERNET CABLE
Definition• Cable made of super-thin filaments of glass or other transparent materials that can carry beams of light
Features:•Cable Length (Longest transmission, use of light)•Cost (Fiber Optic is most expensive)•Ease of Installation (Difficult to install)
FIBER OPTIC CABLE
More Features:• Less susceptible to interference• Data can be sent at the speed of light.• A LASER transmitter encodes frequency signals
into pulses of light: ones and zeros are sent through the cable.
• The receiving end of the transmission translates the light signals back into data which can be read by a computer.
FIBER OPTIC CABLE
Definition• Able to connect computers to other computers and printers the same way a wired network is, but without wires and a slower connectivity
Features:•Range (Depends on factors such as wireless card, access point, and obstacles in between)•Cost (Wireless price is dependent upon the complexity of the setup.)•Ease of Installation (Easy)•802.11 (a,b,g,n)•Interference caused by cordless telephones and microwaves
WIRELESS TRANSMISSION
Intranet• A private network that facilitates communication
between departments of an organization or business
• Intranets are accessible by employees inside the organization.
• Cannot be accessed from the outside without the use of an extranet
LIMITED NETWORK CONNECTIVITY
Admin
Shipping
Personnel
Extranet• A network that allows limited access from outside a private network associated with a company• Used for business partners and employees to conduct business from remote locations•Allows business partners to access data to speed up shipping or manage services.
LIMITED NETWORK CONNECTIVITY
AdminShippin
g Personnel
HomeExtranetExtranet
• Based on data flow• Data flow is the flow of bits of data from one
device on the network to another.• Encapsulation – The creating and formatting of
the data to be sent.• De-encapsulation – The removal of the control
information of the message once it reaches the destination.
INTERNET CONNECTIVITY
• Bandwidth – Theoretical amount of data that can be transmitted across a given medium
• Throughput – The actual amount of data that can be transmitted across a given medium
• Units of Measurement:• Bits per second (bps) = a small text message• Kilobits per second (Kbps) = a text document• Megabits per second (Mbps) = one or two photos• Gigabits per second (Gbps) = a movie
MEASURING INTERNET DATA FLOW
• Bandwidth refers to ideal conditions for network speed.
• How fast could you go if you were the only caron the highway?
BANDWIDTH
• Throughput accounts for the resistance of the medium (the road in this case).
• What if the road wasn’t straight, or there was road construction?
THROUGHPUT
Network Limitations:•Data type•Topology•Congestion•Computer processing
CATEGORIES OF INTERNET SPEED
The speed at which a user can retrieve data from the Internet
DOWNLOAD SPEED
The speed at which a user can send data to a remote location on the Internet
UPLOAD SPEED
The lag, or length of time, that occurs between each point during information transfer
LATENCY
LINKING TO THE INTERNET
To link to the Internet, the user needs to set up service with a company that has a permanent connection and that can provide temporary access to users
INTERNET SERVICE PROVIDER
To connect to the Internet, a computer must have a unique identifier
INTERNET PROTOCOL ADDRESS
SECURITY RISKS
An intrusion to the network
Types:• Hacker• Phishing• Spyware• Adware• Malware
UNAUTHORIZED ACCESS
A person who finds and exploits weaknesses of a computer
HACKER
The act of masquerading as a trustworthy website or other entity to acquire user information
PHISHING
Malicious software meant to gain access, disrupt computer operation, or gather sensitive information
MALWARE
A type of malware that collects user information by tracking the habits of users
SPYWARE
Advertising software that automatically generates advertisements
ADWARE
A computer program that replicates itself
VIRUS
A form of malware that uses the network to spread from host to host
WORM
A standalone, malicious program that gives access from the infected computer to another computer
TROJAN HORSE
An attempt to use another’s identity to commit a crime
IDENTITY FRAUD
• User awareness and education
• Anti-virus software• Firewalls• Passwords
• Complex• Confidential• Varied and changed
regularly
PREVENTION METHODS