If you have consecutive fields of zeroes, they can be expressed with two colons. Zero Compression And Leading Zero Compression With IPv6, our non-compressed address has eight sections of four hex values, separated by a total of seven colons. There are some IPv4 fields that are not represented in IPv6:

source address, destination address – they’re now 128 bits.

next header – Equivalent to IPv4’s Protocol field.

hop limit – Roughly equivalent to IPv4’s Time To Live (TTL) field. Every hop decrements this counter by one, and when that counter hits zero - the “time to live” becomes the time to be discarded.

payload length – IPv4’s equivalent is the Total Length field.

This also helps with QoS, allowing us to prioritize traffic flows rather than individual packets.

flow label – No equivalent in IPv4, this field allows a packet to be labeled as part of a particular flow.

The “traffic class” name comes from this field’s ability to allow us to assign levels of importance to a packet via QoS.

traffic class – In IPv4, this was the Type Of Service (TOS) field.

QoS capabilities with IPv6 are far greater, due to many more values within the IPv6 header.

DHCP is still available, but IPv6 nodes can assign themselves an address without the help of a DHCP server via autoconfiguration.

IPv6 offers greater security capabilities.IPv6 was designed with route aggregation/summarisation in mind.IPv6 addressed are 128-bits in size, offering a hugh amount of addresses.

Ipv6 compressing rules