9 Jan
2011
9 Jan
'11
12:03 a.m.
If you define a new protocol version as one that means devices with older protocol generations of firmware/software may not interoperate reliably with devices with new protocol generations of firmware/software, then IPv4 as we know it today is probably at least "IPv7" - address classes was a generational change requiring software/firmware updates (compare addressing in rfc760 verses rfc791), as was classful+subnets and then CIDR.
Regards, Mark.
I think it's defined, instead, in terms of incompatible changes to the content of the packet header. Owen