What is Logical addressing in computer Networks?
communication at the network layer is host-to-host (computer-to-computer); a computer somewhere in the world needs to communicate with another computer somewhere else in the world. Usually, computers communicate through the Internet. The packet transmitted by the sending computer may pass through several LANs or WANs before reaching the destination computer.
For this level of communication, we need a global addressing scheme; we called this logical addressing .
we use the term IP address to mean a logical address in the network layer of the TCP/IP protocol suite.
The Internet addresses are 32 bits in length; this gives us a maximum of 2 to the power of 32 addresses. These addresses are referred to as IPv4 (IP version 4) addresses or simply IP addresses if there is no confusion.
The need for more addresses, in addition to other concerns about the IP layer, motivated a new design of the IP layer called the new generation of IP or IPv6 (lP version 6).
In this version, the Internet uses 128-bit addresses that give much greater flexibility in address allocation. These addresses are referred to as IPv6 (IP version 6) addresses
IPv4 ADDRESSES:
An IPv4 address is a 32-bit address that uniquely and universally defines the connection of a device (for example, a computer or a router) to the Internet
An IPv4 address is 32 bits long.
IPv4 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
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
The IPv4 addresses are unique and universal.
Address Space:
A protocol such as 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 N bits to define an address, the address space is 2N because each bit can have two different values (0 or 1) and N bits can have 2N values.
IPv4 uses 32-bit addresses, which means that the address space is 232 or 4,294,967,296 (more than 4 billion). This means that, theoretically, if there were no restrictions, more than 4 billion devices could be connected to the Internet. We will see shortly that the actual number is much less because of the restrictions imposed on the addresses
The address space of IPv4 is 232 or 4,294,967,296.
Notations:
There are two prevalent notations to show an IPv4 address:
1.binary notation
2.dotted-decimal notation
Binary Notation
In binary notation, the IPv4 address is displayed as 32 bits. Each octet is often referred to as a byte. So it is common to hear an IPv4 address referred to as a 32-bit address or a 4-byte address. The following is an example of an IPv4 address in binary notation:
01110101 10010101 00011101 00000010
Dotted-Decimal Notation
To make the IPv4 address more compact and easier to read, Internet addresses are usually written in decimal form with a decimal point (dot) separating the bytes. The following is the dotted~decimal notation of the above address:
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