TCP/IP for Absolute Beginners

TCP/IP - Transmission Control Protocol - Internet Protocol is the protocol or language computers use to communicate and travel on the internet. Transmission Control Protocol or TCP is the connection oriented protocol used to communicate reliably. Internet Protocol or IP is used to route your computer across the internet or your local network. This language combines these two protocols for computers to communicate regardless of their location.

WAN or Wide Area Networks is when your computer connects to a computer across a large geographic area. Generally the internet is referred to as a WAN.

MAN or Metropolitan Area Networks is when your computer connects between two or more areas in the same geographic area. Building to Building or across a city is considered a MAN.

LAN or Local Area Network is when your computer connects to another computer or device within the same building.

We will look at the acronyms for wireless in a different part.

No two devices on the same network can have the same IP address. Individuals, ISPs, and companies will have a public IP address given by their provider on their router. The router or firewall will generally have a private IP address on the internal side so that multiple computers or devices can connect to the outside world.

Private IP Addresses are listed below:

10.0.0.x

172.16.x.x

192.168.x.x

IP addresses are broken down into octets. These sections contain numbers generally between 1-254. The number 0 (zero) can be used in the second octet and the third octet. Zeros (0) in the first and last octets are considered invalid. Numbers higher than 254 are also considered invalid.

The first octet determines the subnet your computer is on. This determination gives you information about how many computers can be on a network. To break down the first octet, let's look at the chart below.

Class A 1-126

Class B 128-191

Class C 192-223

Example: 192.168.0.15 IP address would be in a Class C subnet.

What does the example above mean? The chart below gives the number of devices (computers, routers, etc.) that can be in a network based on its subnet.

Class A 16 million

Class B 65,000

Class C 254

Now, look back at the sample and you will see the first set of numbers (the first octet) is 206. This puts the computer or device in a class C. Therefore, 254 devices can be used in your network. Generally your router has a private number and you will get a second IP address for your computer. This leaves 252 more computers or devices that can be put into your network.

In part two of this series, we will break down networks into subnets and explain how computers communicate using TCP/IP. This tutorial will not break these IP addresses into bits or dive into complex subnetting. We will examine TCP/IP troubleshooting and cover the 'how-tos'.

This is the fundamental understanding of TCP/IP addresses needed by users to communicate with other computers.