Differences Between IPv4 and IPv6
The following table lists the important differences between IPv4 and IPv6.
| IPv4 | IPv6 |
|---|---|
| IPv4 addresses are 32-bit (four bytes) in length. | IPv6 addresses are 128-bit (sixteen bytes) in length. |
| Maximum of 232 IPv4 addresses are only possible. That is 4,294,967,296 IPv4 addresses. | Maximum of 2128 IPv6 addresses are possible. 340,282,366,920,938,463,463,374,607,431,768,211,456 number of IPv6 addresses are possible. Very huge number indeed. |
| IPv4 addresses are binary numbers represented in decimals. | IPv6 addresses are binary numbers represented in hexadecimals. |
| An example of IPv4 address is 8.8.8.8 | An example of IPv6 address is 2001:4860:4860::8888 |
| Each part of IPv4 address are separated by a dot (.). | Each part of IPv6 address are separated by a colon (:). |
| IPv4 supports Variable Length Subnet Masking (VLSM). | IPv6 does not supports Variable Length Subnet Masking (VLSM). |
| IPv4 header size is between 20 to 60 bytes. | IPv6 header size is 40 bytes. |
| IPv4 has Unicast, Multicast and Broadcast addresses. | IPv6 has Unicast, Multicast and Anycast addresses. |
| IPSec support is only optional. | Inbuilt IPSec support. |
| Fragmentation is done by sender and forwarding routers. | Fragmentation is done only by sender. |
| No packet flow identification. | Packet flow identification is available within the IPv6 header using the Flow Label field. |
| Checksum field is available in IPv4 header | No checksum field in IPv6 header. |
| Options fields are available in IPv4 header. | No option fields, but IPv6 Extension headers are available. |
Address Resolution Protocol (ARP) is available to map IPv4 addresses to MAC addresses. |
Address Resolution Protocol (ARP) is replaced with a function of Neighbor Discovery Protocol (NDP). |
| Address Resolution Protocol (ARP) messages are used to map IPv4 address to MAC address. | Instead, IPv6 uses Neighbour Discovery Protocol (NDP) ’s Neighbour Solicitation (NS) messages to map IPv6 address to MAC address. |
| Internet Group Management Protocol (IGMP) is used to manage multicast group membership. | IGMP is replaced with Multicast Listener Discovery (MLD) messages. |
| Broadcast messages are available. | Broadcast messages are not available. Instead a link-local scope "All nodes" multicast IPv6 address (FF02::1) is used for broadcast similar functionality. |
| Manual configuration (Static) of IPv4 addresses or DHCP (Dynamic configuration) is required to configure IPv4 addresses. | Auto-configuration of addresses is available. |
Written by Jajish Thomas. Last updated on 14th May, 2024.