N ETWORK S YSTEMS 3.02 U NDERSTAND C ONNECTIVITY THROUGH NETWORKS AND THE I NTERNET.

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