What is the difference of IPV4 header and IPV6 header?
IPV4 uses 12 header fields, 20bytes; IPV6 uses 8 header fields, 40bytes. Five fields and IPV4 are the same, and there is three new fields.
IPV6 does not carry out fragmentation. There is no fragmentation of IPV4. IPV6 adjusts the most suitable MTU with discovery process.
IPV6 discovery process can auto adjust the value of MTU according to returned ICMP information.
IPV6 header has no check field and ensures the reliability of data transmission depending on upper layer and data link layer.