Difference Between IPv4 and IPv6

IPv4

• Source and destination addresses are 32 bits (4 bytes) in length.
• IPSec support is optional.
• IPv4 header does not identify packet flow for QoS handling by routers.
• Both routers and the sending host fragment packets.
• Header includes a checksum.
• Header includes options.
• Address Resolution Protocol (ARP) uses broadcast ARP Request frames to resolve an IP address to a link-layer address.
• Internet Group Management Protocol (IGMP) manages membership in local subnet groups.
• ICMP Router Discovery is used to determine the IPv4 address of the best default gateway, and it is optional.
• Broadcast addresses are used to send traffic to all nodes on a subnet.
• Must be configured either manually or through DHCP.
• Uses host address (A) resource records in Domain Name System (DNS) to map host names to IPv4 addresses.
• Uses pointer (PTR) resource records in the IN-ADDR.ARPA DNS domain to map IPv4 addresses to host names.
• Must support a 576-byte packet size (possibly fragmented).

IPv6

• Source and destination addresses are 128 bits (16 bytes) in length.
• IPSec support is required.
• IPv6 header contains Flow Label field, which identifies packet flow for QoS handling by router.
• Only the sending host fragments packets; routers do not.
• Header does not include a checksum.
• All optional data is moved to IPv6 extension headers.
• Multicast Neighbor Solicitation messages resolve IP addresses to link-layer addresses.
• Multicast Listener Discovery (MLD) messages manage membership in local subnet groups.
• ICMPv6 Router Solicitation and Router Advertisement messages are used to determine the IP address of the best default gateway, and they are required.
• IPv6 uses a link-local scope all-nodes multicast address.
• Does not require manual configuration or DHCP.
• Uses host address (AAAA) resource records in DNS to map host names to IPv6 addresses.
• Uses pointer (PTR) resource records in the IP6.ARPA DNS domain to map IPv6 addresses to host names.
• Must support a 1280-byte packet size (without fragmentation).