Comment by throw0101a
Comment by throw0101a 20 hours ago
> We might have been able to migrate to IPv6 wholesale when the Internet was much smaller in the early 90s.
In the early 1990s IPng/IPv6 was not yet invented, and when it was being considered they realized a flag-day (like (mostly) happened with NCP->IP) was unlikely:
We believe that it is not possible to have a "flag-day" form of
transition in which all hosts and routers must change over at
once. The size, complexity, and distributed administration of the
Internet make such a cutover impossible.
Rather, IPng will need to co-exist with IPv4 for some period of
time. There are a number of ways to achieve this co-existence
such as requiring hosts to support two stacks, converting between
protocols, or using backward compatible extensions to IPv4. Each
scheme has its strengths and weaknesses, which have to be weighed.
Furthermore, we note that, in all probability, there will be IPv4
hosts on the Internet effectively forever. IPng must provide
mechanisms to allow these hosts to communicate, even after IPng
has become the dominant network layer protocol in the Internet.