Networking & The Internet

Data Flow

The OSI Model

The OSI Model

Physical Please

Data Do

Network Not

Transport Throw

Session Sausage

Presentation Pizza

Application Away

Application All

Presentation People

Session Seem

Transport To

Network Need

Data Data

Presentation Processing

IP Addresses

What is an IP address?

What does IP stand for?

What is a MAC address?

Why would you use a static IP address?

What does www.google.com refer to?

The OSI Model

IP Addresses work at the Network Layer of the OSI model

To make it easier for us humans to remember, IP addresses are

normally expressed in decimal format as a "dotted decimal

number“ like this:

216.27.61.137

The OSI Model

IP Addresses are in fact saved in binary. So this address:

216.27.61.137

Actually is read as this:

11011000.00011011.00111101.10001001

The OSI Model

IP Addresses are 32 bit numbers. Why? Because they are made up of

4 x 8bit binary numbers = 32

Each digit = 1 ‘bit’ of memory

This means that worldwide there are a possible 4,294,967,296 IP

addresses

The OSI Model

However, within IP addresses there are certain reserved numbers.

The first number or ‘octet’ (eight bits) shows the type of network the

IP belongs to:

001 – 126 are Class A Addresses

Class A are large networks consisting of many Ips

Class A IPs are stored as:Network Node 127. 0.0.1

Up To16,777,214 Possible IPs

The OSI Model

128 – 191 are Class B Addresses

Class B are medium networks consisting of a large number of IPs

Class B IPs are stored as:Network Node 127.0. 0.1

Up To 65,534 Possible IPs

The OSI Model

192 - 223 are Class C Addresses

Class C are small networks consisting of several IPs

Class C IPs are stored as:Network Node127.0.0. 1

Up To254

Possible IPs

The OSI Model

Some IPs are ‘reserved’

Home, or Loopback: 127.0.0.1

Broadcast Address: 255.255.255.255

The OSI Model

Within Networks, IPs are Subnetted to allow IPs to be assigned within the

network.

In your Internet Browser go to:www.whatismyip.com

What information can you find about the network you are on?

Homework – Due in next Friday

What is the Purpose of Subnetting?

Discuss your findings in a short essay format (more than a page, less than

five)

Essay format: Intro, discussion, conclusion, SOURCES!