On 2/13/2012 4:17 PM, Brian E Carpenter wrote:
People say this from time to time, but it's a complete myth.
well, not completely...
IPv4 provides no mechanism whatever for addresses greater than 32 bits.
Therefore, mathematically, there is no possible design for an IP with
bigger addresses that is transparently backwards compatible. We've known
that since at least 1992.
The path that the IETF followed ensured the maximum amount of incompatibility.
Really a completely independent stack.
In contrast, the IETF could easily have chose a path toward minimizing
incompatibility that would have allowed IPv6 to interwork with IPv4, within the
limitations of the v4 address space.
That is, the IETF could begun IPv6 by assigning to it IPv4 addresses, reserving
the remainder for latter definition and allocation. It could have targeted
simple, basic reformatting at the IP level to permit early IPv6 adoption to
require a minimal gateway for interworking with the IPv4 world.
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