[135362] in North American Network Operators' Group
Re: IPv6: numbering of point-to-point-links
daemon@ATHENA.MIT.EDU (Marco Hogewoning)
Mon Jan 24 08:10:54 2011
From: Marco Hogewoning <mch-nanog@xs4all.nl>
In-Reply-To: <FC64B3384195884588D252343702D23F01854588@ICABEXCCLU01B.int.sonofon.dk>
Date: Mon, 24 Jan 2011 14:10:48 +0100
To: Lasse Jarlskov <laja@telenor.dk>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> While reading up on IPv6, I've seen numerous places that subnets are =
now
> all /64.
>=20
> I have even read that subnets defined as /127 are considered harmful.
RFC3627, with a lot of discussion in the IETF on this. See also =
https://datatracker.ietf.org/doc/draft-ietf-6man-prefixlen-p2p/
> However while implementing IPv6 in our network, I've encountered =
several
> of our peering partners using /127 or /126 for point-to-point links.
I personally don't any benefit in using /126 subnets.
> What is the Best Current Practice for this - if there is any?
>=20
> Would you recommend me to use /64, /126 or /127?=20
>=20
> What are the pros and cons?
=46rom an operational point of view there is a risk that be using /64 =
somebody can eat away a lot of memory by either scanning or even =
changing addresses. This is also described in the draft above...
I would personally recommend to at least always assign the /64, even if =
you would decide to configure the /127. RFC 3627 has been around long =
enough that you will keep running into equipment or software that won't =
like the /127. In which case you can always revert back to /64.
This will also allow you to use easy to remember addresses like ::1 and =
::2, saving you the headache of a lot of binary counting.
Grtx,
Marco=
