Internet Protocol : IPV4 Introduction

IPV4 Introduction

• The identifier used in the IP layer of the TCP/IP protocol suite to identify each device connected to the Internet is called the Internet address or IP address. 
• An IPv4 address is a 32-bit address that uniquely and universally defines the connection of a host or a router to the Internet.
• IP address is the address of the interface.
• Pv4 addresses are unique. They are unique in the sense that each address defines one, and only one, connection to the Internet. 
• Two devices on the Internet can never have the same address at the same time. 
• However, if a device has two connections to the Internet, via two networks, it has two IPv4 addresses. 
• The IPv4 addresses are universal in the sense that the addressing system must be accepted by any host that wants to be connected to the Internet.

Notation
There are three common notations to show an IPv4 address: binary notation (base 2), dotted-decimal notation (base 256), and hexadecimal notation (base 16). 

Binary Notation: Base 2

• In binary notation, an IPv4 address is displayed as 32 bits with spaces inserted between each octet/byte (8 bits) for easy reading. 
• IPv4 address referred to as a 32-bit address, a 4-octet address, or a 4-byte address. 

Example: IPv4 address in binary notation: 01110101 10010101 00011101 11101010

Dotted-Decimal Notation: Base 256

• To make address more compact and easier to read, an IPv4 address is usually written in decimal form with a decimal point (dot) separating the bytes. This format is referred to as dotted-decimal notation. 
• Each number in the dotted-decimal notation is between 0 and 255.

 

Hexadecimal Notation: Base 16

Sometimes an IPv4 address in hexadecimal notation. Each hexadecimal digit is equivalent to four bits. This means that a 32-bit address has 8 hexadecimal digits. This notation is often used in network programming. 

A group of 4 bits with its hexadecimal equivalent. the hexadecimal notation has no added spaces or dots; however, 0X (or 0x) is added at the beginning or the subscript 16 at the end to show that the number is in hexadecimal.

Example

a. 0X810B0BEF or 810B0BEF₁₆

b. 0XC1831BFF or C1831BFF₁₆

Address Space

• A protocol like IPv4 that defines addresses has an address space. An address space is the total number of addresses used by the protocol. 
• If a protocol uses b bits to define an address, the address space is 2 b because each bit can have two different values (0 or 1).
• IPv4 uses 32-bit addresses, which means that the address space is 2 32 or 4,294,967,296 (more than four billion).