Difference between IPv4 and IPv6

IPv4 and IPv6 are internet protocol versions, with IPv6 being an upgraded version of IPv4. There are several differences between the IPv4 and IPv6 protocols, including their functionality, but the most important difference is the quantity of addresses (Address space) that they create.

Read through this article to find out more about IPv4 and IPv6 and how they are different from each other.

What is Internet Protocol (IP)?

The Internet Protocol is a set of rules that allows our computers to communicate via the Internet. IP addresses are basically in charge of directing the data packets to their correct destinations. IP controls all Internet traffic. Data packets containing the IP addresses of their points of origin and destinations travel on the Internet.

When you type an URL on your browser, a data packet including your IP address is transmitted to the web server's IP address, and the website corresponding to the URL is then served back to your device over the Internet.

What is IPv4?

IPv4 is a major protocol in the TCIP/IP suite. IPv4 addresses provide a way to uniquely identify the hosts in a network. IPv4 uses 32-bit logical addresses. Depending on the network type, there are various ways to configure IPv4 with multiple devices, including manual and automatic configurations.

IPv4 uses the best-effort model, which means it does not guarantee delivery of data to a host or avoid duplicate delivery.

For Ethernet communication, IPv4 uses five classes of 32-bit addresses − A, B, C, D, and E. The bit length for addressing the network host differs between Classes A, B, and C. Multicasting is reserved for class D addresses, whereas future use is reserved for class E addresses. IPv4 has a limit of 4.20 × 109 host addresses that it can allocate to end-users.

What is IPv6?

As the popularity of the Internet grew in the 1990s, it was soon realized that the number of IP addresses that IPv4 can create is restricted, and it will get exhausted. Hence, the Internet Engineering Task Force (IETF) had developed IPv6, which is a better and upgraded version of IPv4 that was intended to replace IPv4 eventually.

IPv6 provides 128-bit IP addresses, which means it can generate 3.4 × 1038 addresses. In layman's terms, it can generate trillions of trillions IP addresses. IPv6 reserves blocks of numbers for particular purposes. It prohibits using specific numbers entirely, so the total number of IPv6 addresses should be slightly less. Nonetheless, the amount of IPv6 addresses is almost endless, so there would be no dearth of IP addresses in the future.

IPv6 addresses follow the same design principles. The addresses are divided into eight groups of four hexadecimal digits separated by colons. Most IPv6 addresses do not use all of their 128 bits, resulting in fields that are either entirely zeros or are padded with zeros. The two colons (::) can represent a contiguous 16-bit field of zeros in IPv6 addressing scheme.

Difference between IPv4 and IPv6

The following table highlights the major differences between IPv4 and IPv6 −

KeyIPv4 ProtocolIPv6 Protocol
Address ConfigurationIPv4 has an address length of 32-bit represented in decimal format. It supports Manual and DHCP configuration.IPv6 has a 128-bit address length represented in hexadecimal format. It supports auto-configuration and renumbering configuration.
Address SpaceIn case of IPv4, a total number of 4.20 × 109 addresses could get generated.In case of IPv6, the total number of IP addresses that could be generated is 3.4 × 1038 which is much greater than the number produced by IPv4.
SecureIPv4 is being used as less secure protocol, as its security section is dependent on the application, i.e., it is proportional to the security that is provided or implemented at the application level.IPv6 has its inbuilt security feature named as IPSEC (Internet Protocol Security) which provide additional security feature along with the security provided or implemented at application level.
FragmentationIn case of IPv4, fragmentation is performed by both the Sender and the Forwarding routers.In case of IPv6, fragmentation is performed only by the sender routers.
AuthenticationIPv4 does not provide Encryption and Authentication facilities.IPv6 provides both Encryption and Authentication facilities.
Header SizeIn IPv4, the Request header is not fixed and it may be between of 20-60 bytes in size.In IPv6, the Request header is of fixed size, i.e., 40 bytes.


IPv4 creates 4.20 × 109 unique network addresses, which is an insufficient in number, and as a result, the Internet is running out of space. IP version 6 (IPv6), on the other hand, generates 3.4 × 1038 addresses and provides a scalable and adaptable solution to the existing issue.

Updated on: 22-Aug-2022

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