IPv6 end user addressing
William Herrin
bill at herrin.us
Sat Aug 6 18:28:41 UTC 2011
On Fri, Aug 5, 2011 at 12:17 PM, Brian Mengel <bmengel at gmail.com> wrote:
> In reviewing IPv6 end user allocation policies, I can find little
> agreement on what prefix length is appropriate for residential end
> users. /64 and /56 seem to be the favorite candidates, with /56 being
> slightly preferred.
Hi Brian,
/64 is *strongly* discouraged. I'd go so far as to say that when we
look back 3 years from now, anybody who assigned /64's to end user
networks will be considered short-sighted bordering on foolish. Assign
a /128 if you know the downstream is exactly 1 host (not a LAN, not a
PC with virtual machines, exactly one computer) or else assign at
least a /60.
> I am most curious as to why a /60 prefix is not considered when trying
> to address this problem. It provides 16 /64 subnetworks, which seems
> like an adequate amount for an end user.
Every time someone needs more than the standard assignment, you have
to make a custom assignment with the manpower cost to make it and
maintain it. This will happen often with /64, occasionally with /60
and rarely with /56.
On the flip side, /56 allows for 16M end-users in your /32 ISP
allocation. After which you can trivially get as many additional /32's
as you want. Is there any reason you want to super-optimize to get
268M end-users squashed in that /32?
Regards,
Bill Herrin
--
William D. Herrin ................ herrin at dirtside.com bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004
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