IPv6 is based on IPv4, it is an evolution of IPv4. So many things that we find with IPv6 are familiar to us. The main differences are:
- Simplified header format. IPv6 has a fixed length header, which does not include most of the options an IPv4 header can include. Even though the IPv6 header contains two 128 bit addresses (source and destination IP address) the whole header has a fixed length of 40 bytes only. This allows for faster processing.
Options are dealt with in extension headers, which are only inserted after the IPv6 header if needed. So for instance if a packet needs to be fragmented, the fragmentation header is inserted after the IPv6 header. The basic set of extension headers is defined in RFC 2460.
- Address extended to 128 bits. This allows for hierarchical structure of the address space and provides enough addresses for almost every 'grain of sand' on the earth. Important for security and new services/devices that will need multiple IP addresses and/or permanent connectivity.
- A lot of the new IPv6 functionality is built into ICMPv6 such as Neighbor Discovery, Autoconfiguration, Multicast Listener Discovery, Path MTU Discovery.
- Enhanced Security and QoS Features
I hope this answers your question. Kind regards, Silvia
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