Not Making Use of 240/4 NetBlock

Randy Bush randy at
Sun Mar 13 18:56:17 UTC 2022

> Yet the four largest cable networks and all of the mobile networks in the
> US have had full IPv6 support for years as do AWS, Google, Azure, Digital
> Ocean, Linode, and many other hosting providers.
> Could you explain what "most" means where you are?

a vast number of large non-us mobile networks and non-us fixed eyeball
networks use cgn, sad to say.

as saku says, when v6 was 'designed', the expected transition time was
relatively short.  yes, they had negative ops clue; in fact, ops were
openly declared to be the enemy of the v6 'architects' (remember NLA and
TLA).  this led, among other things, to the short-sighted plan for dual
stack to be the only needed transition mechanism.  the first problem
with this is that it requires as much v4 space as v6 space, oops.  thus
was born the plethora of transition mechanisms.

imiho, v6 will continue to slowly deploy with some lulls and some
spurts.  and mailing list religious rants about it will continue
unabated.  in parallel, efforts to de-frag the v4 space are worthwhile,
though they will only slightly alleviate the v4 shortage.

we do what we can.  i only wish we would make less ineffective noise
about it.


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