Re: Re: Just how big is IPv6?
  By: Deon George to Arelor on Fri Jan 03 2025 03:24 pm

 > Hmm... its worked for me, but then my setup my not be as complicated as
 > yours? I get an /60 from my current ISP (my previous one gave me a /56) -
 > and my router dished it out as /64's to each lan interface as it needed to.
 > At one point, I dished out a /62 to a downstream router, and it split it up
 > to /64s for it's lan interfaces.

That is how it is supposed to work, that is how I have never seen it work in the
wild.

To me, it is like UEFI key management. It is great when it works but I rarely
see anybody get it right. So far I know no ISP in my country that does not give
you the bare minimum /64 assignation and then can't deal with PD.

And, to me, that is a big part of the point: if you depend on your ISP's DHCPv6
to properly configure your LAN the whole thing is a bit brittle. Firewall
specifications for IPv6 filtering require a whole lot of traffic to be allowed
from and to your ISP because changes in the ISP state have repercussions in the
state of your LAN. What happens if the ISP's DHCP service goes down? Chances are
your router keeps operating with the last lease set it got, but that leaves your
LAN in an inconsistent state. Meanwhile an IPv4 LAN can operate pretty much
forever in a consistent state if the whole Internet suddenly disappears.


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