IPv4 Addressing

IPv4 (Internet Protocol version 4) is a widely used protocol for identifying and routing data packets across networks. IPv4 addresses are 32-bit numeric labels assigned to devices on a network to enable communication. These addresses are typically written in a format like “xxx.xxx.xxx.xxx,” where each “xxx” represents a decimal number ranging from 0 to 255. An IPv4 address consists of four sets of these numbers separated by periods.

In other words, IPv4 addresses are 32-bit integers represented by four decimal numbers separated by periods, such as 172.16.2.1. Each decimal number can range from 0 to 255, corresponding to 8 bits of binary representation (0 to 255).

IPv4 addressing is a fundamental concept in computer networks.

The addresses are divided into two parts: the network part and the host part. The network part is determined by the subnet mask, a numeric series showing the network part of an IP address. The host part represents individual devices on the network.

Three addressing modes in IPv4:

1. Unicast addressing mode: data is sent to a single destination host.

2. Broadcast Addressing Mode: packets are addressed to all hosts on a network segment using a special broadcast address, 255.255.255.255.

3. Multicast addressing mode: Packets are sent to a group of hosts that have joined a multicast group.

These addressing modes allow efficient communication within networks and on the Internet.

Key points about IPv4 addressing:

1. Classes of IPv4 Addresses: IPv4 addresses are divided into different classes based on the size and structure of the network. The main classes are A, B, C, D and E.

- Class A: These addresses have their first bit set to 0 and can range from 0.0.0.0 to 127.255.255.255. Large organizations typically use class A addresses.

- Class B: The first two bits of class B addresses are 10 and range from 128.0.0.0 to 191.255.255.255. They are used for medium-sized networks.

- Class C: Class C addresses start with the first three bits as 110 and range from 192.0.0.0 to 223.255.255.255. They are suitable for smaller networks.

- Class D: Class D addresses are reserved for multicast groups, starting with the first four bits as 1110.

- Class E: Class E addresses, starting with the first four bits as 1111, are reserved for experimental purposes.

2. Private versus Public Addresses: Some address ranges are reserved for private use on networks and should not be routed on the public Internet. These private address ranges include:

- Class A: 10.0.0.0 to 10.255.255.255

- Class B: 172.16.0.0 to 172.31.255.255

- Class C: 192.168.0.0 to 192.168.255.255

Devices on private networks typically use these addresses and are typically NAT (Network Address Translation) enabled to access the Internet using a single public IP address.

3. Subnets: IPv4 addresses can be subnetted, dividing a larger network into smaller ones for better address management and routing efficiency. Subnet masks are used to determine which part of an IP address represents the network and which part represents the host within that network.

4. Address Exhaustion: IPv4 address exhaustion is a significant problem because the number of unique IPv4 addresses is limited to 2^32 (approximately 4.3 billion addresses). This limitation led to the development of IPv6 (Internet Protocol version 6), which uses 128-bit addresses, providing an exponentially larger address space to accommodate the growing number of devices connected to the Internet.

5. IPv4 Address Assignment: IPv4 addresses can be assigned statically (manually configured) or dynamically (automatically assigned by DHCP - Dynamic Host Configuration Protocol) to devices on a network. DHCP is commonly used in modern networks to simplify address management.

6. Example: An example of an IPv4 address is 192.168.1.1, where 192 is the network part and 1.1 is the host part. In this case, it is a Class C private address.

In summary, IPv4 addressing is the foundation of the Internet and networks. Still, its limitations, such as address exhaustion, have led to adopting IPv6 to accommodate the increasing number of devices connected to the Internet.

(1) IPCisco.

(2) Tutorialspoint.

(3) Geeks.