Questions on IPv6 deployment

William Herrin bill at
Tue Jan 17 16:48:09 UTC 2017

On Mon, Jan 16, 2017 at 10:11 AM, Matthew Crocker
<matthew at> wrote:
> I’m looking for some direction/reading list of how to properly configure IPv6.  I’ve read to use a /64 for PtP interfaces and I’ve read use a /128 instead.    Assign all loopbacks from the same /64, use a different /64 for each loopback. Ect, ect.

Hi Matthew,

Suggest /128's for loopbacks and /124's for point to points, all from
the same /64. This way you don't burn space needlessly, don't open
yourself to neighbor discovery issues on point to points and can
filter inbound Internet packets to that /64 in one fell swoop so that
it's harder to hit your routers directly. Just make sure not to filter
the outbound packets.

Reminder: No matter what size you pick, use nibble boundaries for
visual and DNS convenience. So /124, not /126.

Bill Herrin

William Herrin ................ herrin at  bill at
Owner, Dirtside Systems ......... Web: <>

More information about the NANOG mailing list