Networking and Operating Systems

Networking

What is it?

Things that are hooked together.

Computer Network- Computers that are connected together.

LAN and WAN

LAN

Local Area network

Computers that are connected together in the same building or room.

WAN

Wide Area Network

Computers that are connected together but are geographically further apart.

LAN Networks

Peer-to-Peer

Connecting your computer and my

computer. Everyone is

Equal.

File-Server Based

A main server computer serves files to users who

need to access them.

Advantages and Disadvantages

AdvantagesPeer to Peer cost lessFile Server can handle many users.If another user’s computer goes down, it does not affect the file server.

DisadvantagesFile Server cost more moneyData can be difficult to back up on a peer to peer network.Peer to peer is not useful for large businesses.

Network Cables

One of the most important parts of a network.

Cables determine how much information can go back and forth from one station to another.

They are commonly used with LANs.

The type of cable used depends on the network’s topology, protocol, and size.

One must recognize these difference in order to create a successful network.

Types of Cables

Coaxial Cables

Fiber Optic Cables

Unshielded Twisted Pair

Shielded Twisted Pair

Coaxial Cables

Has a single copper conductor in the center that is covered with a plastic layer.More expensive than twisted pair cablesLess vulnerable to outside interferenceAble to carry information over long distances. Not used much anymore.

Fiber Optic Cables

Made from glass fiber as thin as human hair.

Transmits light instead of electricity which eliminates electrical interference.

Want to use if information has to be carried great distances (ATT)

Expensive

Unshielded Twisted Pair

Can connect one device to another. Is the most popular and best option for school networks. Like telephone wire Has 4 pairs of wires Each is twisted with a different number of twists

per inch. The tighter the twisting, the higher the supported transmission rate.

Category 3 or 5 is the recommended style of wire because it is the most affordable.

Shielded Twisted Pair

Is suitable for environments with electrical interference.

Can be quite bulky due to the extra shielding.

Type Cost Speed Distance

Twisted Pair(most popular)

$ Slow to fast

Short

Coaxial $$ Fast Medium

Fiber Optic

$$$ Fastest there is

Longest there is

Wireless LANs

Use high frequency radio signals, infrared light beams, or lasers to communicate information from one area to another. Must have a transceiver/antenna to send and receive data. Beneficial to use if users have laptops or if building is too old to install cable. They are very expensive.Security issues are still be worked on.

Tips on installing Cable

Always use more cable than needed.

Leave plenty of slack.

Test all cables as they are installed.

Tie cables using a cable ties.

If running cable on the floor, protect the cable by using some type of protective covering.

Network HardwareRepeaters- device that extends the distance of a particular network. Sends signals back and forth.

Hubs- Used to connect network nodes(computers) to network backbone.

Bridges- An intelligent version of a repeater.

Routers- More intelligent bridge. They examine data and send it to the appropriate place.

Switches- Switch connections from one port to another.

Security

Security is one of the hardest things to maintain on a network.User names and Passwords are used A Network Administrator is responsible for

the security of the users and information on the network

Viruses, Worms, Trojan Horses, Logic Bombs

Virus- A program that spreads by infecting other files with a copy of itself. Worm- A program that propagates by sending copies of itself to other computers, which run the worm and then send copies to other computers.Trojan Horses- A program that purports to do something interesting or useful and then performs malicious actions in the background while the user is interacting with main program. Logic Bomb- Malicious pieces of programming code inserted into an otherwise normal program.

Operating System

The software that controls operations of all parts of the computer system, such as storage and input/output devices.

When the computer is booted, the operating system software is loaded from the ROM or a disk.

Once the operating system is loaded, the computer is under its control.

DOS and Windows 95/98

DOS

Single-program operating system.

Character-based operating system.

Has to use the DOS commands.

Windows

Multitasking operating system

Provides a graphic user interface