Format of IPv6 Datagram
Datagram

RFC 2460 is the basic building block of IPv6. It mainly defines the format of datagram. IPv6 datagram is composed of header, extension headers and data. It has a constant length and optional information is moved into separate extension headers as opposed to IPv4 datagram. Extension headers may or may not place after header. The total length of the IPv6 header is twice large than IPv4 header. It increased from 20 octets to 40 octets.

Checksum field was removed from the header because the lower layer of network architecture performs it.

IPv6 Header has the following format:

IPv6 Header Format

Description of individual fields of IPv6 header: