Basic Networking by B.Mills - PowerPoint Presentation

Slide1

Basic Networking

by

B.Mills

Show adapted from

www.newboston.org

The purpose of a network is to share data

Local Area Networks (LANs) are restricted to rooms, buildings and smaller geographical areas

LANs are often prohibited from outside (Internet) access. For example personal

student information and grades are the property of LAN-based servers and cannot be

Freely.

The more exclusive the data is, the more likely it will be within a LAN environment.

MANs are similar to LANs but have a topology which may be determined by the type of data

being transferred. For example: research between universities or hospitals and other entities

s

uch as police or emergency services.

WANs are similar to MANs but have an topology greater than 30 miles. The most well-

Known WAN is the Internet.

Your operating system won’t let other computers access your computer. You must go through

a server. You can think of a server as both a security guard and translator. This is the basis of

how the Internet works.

Servers are home to websites. Websites such as thenewboston.org are on a server. Servers

can be anywhere.

Cebilingual.com’s

server is located in California.

The job of your browser is to use the http protocol and ask for files from the server. The

browser will also translate text and symbols so that you can read them (session layer)

In business, the ‘client’ is always the one who is receiving the ‘service’. Therefore, your

computer is a ‘client’ because it is receiving files and data. If you are ‘giving’ the files, then

you are the ‘host’. For example if you give a party at your house, you are the ‘host’ and you

are ‘serving’ food and drinks.

NIC (Network Interface Card) connects to a computer’s motherboard. These days, NIC cards

are built into the motherboard.

Protocols are rules that are allowed in a conversation between nodes. In a typical human

conversation only one person talks at a time. If I say ‘hello’ then I expect your answer to

be ‘hello’, ‘good morning’, hi, etc…. A common protocol for the Internet is ‘http’

(hypertext transfer protocol). For http, one person talks at a time and a response is expected.

In this example I ask

the www.thenewboston.com

server for a file called ‘

index.php’

using the http

protocol

Topology means: how your computer network is arranged. In the “Bus” arrangement

Above, the ‘T’ is called a ‘terminator’ which means that when the signal has run along the

backbone ‘the wire in the middle’ the signal is killed so that it won’t keep bouncing back

and forth and repeating itself.

In this topology, all the devices are connected to one main ‘ring’ . I may not look like a

perfect ring after connecting all your devices but the signals will move in a ring pattern.

A ring has no terminators. If you request a file, it will ‘ask’ each node until it finds the machine

that has the file (probably the server). Even after it finds the file, it will continue to ask all the

nodes until the request returns to your machine.

This topology is the most popular and is used in most personal home networks. The router

Is the central device which connects all nodes. The router then connects all devices to the

Internet. Routers are not expensive but the router is the weak point because if the router

fails, so does the network.

The star network can easily be expanded.

This topology is the most complex. It is similar to driving a car: if one road is closed, you

can take another road to your destination.

The OSI model gives a broad overview of networking and how data is passed from one node

to another.

The Modem connects your network to the Internet

The router decides what path the data will take.

For example if you are receiving a file from

Google , the router knows which computer to send it to.

Because the router has only a limited number of ports, a switch is an extension of the router

that allows you to expand your network

Binary code is all the 0’s and 1’s that the computer understands but you don.t

Here is an example of the number 19 in

bianary

code.

Will the number 128 fit into 19? No! so we give it a 0. 64? No!, 32? No! . 16? Yes! So we give it

A 1.

A basic IPv4 Internet IP address has 32 bits.

Each of these 8bit sections are called Octets.