The RFC's', RFC 1826 and RFC 1827 specify the standards for the extension headers authentication and security respectively. Header The IP - next generation header is simplified to achieve less processing time on each hops. The IP options' fields, fragmentation fields are removed from the header and moved to extension headers. Refer to separate section on this. The routers can use the flow label, source address combination to identify a data packet as belonging to a particular flow.
Source assigns the number to all packets belonging to the same flow.
See section on extension headers. The IPv6 packet can include various extension headers following the IPv6 header. The inclusion of extension headers gives flexibility to the internet designers to include more information in the packet as and when needed. All extension headers are processed at the destination of the packet with the exception of one. The 'next header' field in each of the extension headers indicate the type of the extension header that follows.