[175227] in North American Network Operators' Group
Re: IPv6 Default Allocation - What size allocation for Loopback
daemon@ATHENA.MIT.EDU (joel jaeggli)
Sun Oct 12 18:44:38 2014
X-Original-To: nanog@nanog.org
Date: Sun, 12 Oct 2014 15:44:17 -0700
From: joel jaeggli <joelja@bogus.com>
To: William Herrin <bill@herrin.us>, Faisal Imtiaz <faisal@snappytelecom.net>
In-Reply-To: <CAP-guGXezFUSSpDznCtb6DZNXpV=2RBdWGH+sf-xSdKj_mCsiw@mail.gmail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
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On 10/12/14 3:00 PM, William Herrin wrote:
> On Sat, Oct 11, 2014 at 1:41 AM, Faisal Imtiaz <faisal@snappytelecom.ne=
t> wrote:
>> A follow up question on this topic..
>>
>> For Router Loopback Address .... what is wisdom in allocating a /64 vs=
/128 ?
>> (the BCOP document suggests this, but does not offer any explanation o=
r merits of one over the other).
>=20
> Hi Faisal,
>=20
> One of the viewpoints held by some in the IETF is that an IPv6 address
> is not 128 bits. Rather, it is 64 bits of network space and 64 bits of
> host space. I'm told this viewpoint is responsible for the existence
> of a 128 bit address instead of IPv6 using 64 bit addresses.
>=20
> If you follow that reasoning, the subnet mask should always be /64, no
> matter where the address is assigned.
https://tools.ietf.org/html/rfc6164
Is a standards track document.
it is imho a repudiation of the assumptions about the dimensions of the
host field.
> There are, of course, excellent operational reasons not to religiously
> follow that plan.
>=20
> Regards,
> Bill Herrin
>=20
>=20
>=20
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