IPv4 vs IPv6: What's the Difference

Originally, IP addresses were categorized into five (5) classes, namely A, B, C, D, and E. Among these, classes A, B, and C hold the utmost significance, as the initial bits of an address ascertain its class. These classes vary in terms of how much of the address is allocated to the network address and how much is dedicated to the host address. Classes A, B, and C are crucial for addressing needs in the Internet Protocol (IP) system.

Internet Protocol Versions

With the exponential growth of the Internet of Things (IoT), the number of connected devices is increasing daily. This surge in connectivity, coupled with the traditional addressing system based on classes A, B, and C, has led to a critical shortage of available IP addresses (IPv4). To address this issue, alternative technologies like subnetting, NAT (Network Address Translation), and CIDR (Classless InterDomain Routing) have been utilized to temporarily alleviate the addressing problem.

However, to meet the ever-growing demands of the internet, a more substantial solution was required. As a result, Internet Protocol version 6 (IPv6) was introduced, offering a significant improvement over IPv4 with its adoption of 128-bit addressing instead of the previous 32 bits. This upgrade resulted in a vast increase in the number of available addresses, ensuring a more sustainable and scalable internet infrastructure. Currently, IPv4 coexists alongside its newer counterpart, but eventually, the transition will fully embrace IPv6 to support the continuously expanding digital landscape.

What is IPv4?

Internet Protocol version 4, commonly known as IPv4, is the fourth iteration of the Internet Protocol (IP) and was the first version to gain widespread adoption. Introduced as early as 1983, IPv4 remains the most widely recognized method for identifying devices on a network. It is designed for use on packet-switched Link Layer networks, such as Ethernet, and employs a 32-bit address format, providing a total of approximately 4.3 billion possible addresses. As of today, IPv4 remains the predominant Internet Protocol, carrying an overwhelming 94% of all internet traffic. IPv4 addresses are typically represented in dot-decimal notation, comprising four decimal numbers ranging from 0 to 255, separated by dots for ease of identification, for example:

What is IPv6?

Internet Protocol version 6 (IPv6) represents the next generation of IP address standard, intended to complement and eventually replace the current IPv4, which is still widely utilized by many internet services today.

IPv6 addresses are significantly longer, consisting of 128 bits or 16 octets, making them four times larger than IPv4 addresses. To be exact, IPv6 offers an astounding number of unique addresses, reaching 340,282,366,920,938,463,463,374,607,431,768,211,456. Unlike IPv4, which employs the decimal system, IPv6 adopts the hexadecimal system for address assignment. These addresses are organized into eight groups of numbers, each separated by a colon (:), with each group containing a pair of hexadecimal numbers. This expansion of address space in IPv6 ensures a virtually unlimited supply of unique addresses, accommodating the ever-growing number of connected devices in the evolving digital landscape., for example:

Key Differences Between IPv4 and IPv6

IPv4	IPv6
32-Bit IP address	128-Bit IP address
Separated by a dot(.)	Separated by a colon(:)
4.29×109 address space	3.4×1038 address space
Numeric addressing method	Alphanumeric addressing method
Header of 20-60 bytes	Header of 40 bytes fixed
Offers 12 header fields	Offers 8 header fields
Supports broadcast	Doesn't support broadcast
Supports VLSM (Virtual Length Subnet Mask)	Doesn't support VLSM
Detected and computed the checksum error	Checksum error is not computed in IPV6
QoS feature is not very efficient	In-built QoS feature and is very efficient
Fragmentation performed by Sender and forwarding routers	Fragmentation performed only by sender
Supports Manual and DHCP address configuration	Supports Auto and renumbering address configuration
Encryption and Authentication facility not provided	Encryption and Authentication are provided
Uses ARP (Address Resolution Protocol) to map to MAC address	Uses NDP (Neighbour Discovery Protocol) to map to MAC address
Still in use by the remaining 94%	Used by less than 6% of the networks

IPv6 brings several advantages, including:

1. More Efficient Routing
2. Auto-configuration
3. More Efficient Packet Processing
4. Multi cast and any cast functionalities
5. Built-in authentication and privacy support
6. Simplified Network Configuration
7. Improved security and authentication features

Benefits of using IPv4 and IPv6 together:

1. Dual-Stack Network
2. Tunneling
3. Network Address Translation-Protocol Translation (NAT-PT) aka RFC-2766