[175100] in North American Network Operators' Group
Re: IPv6 Default Allocation - What size allocation are you giving out
daemon@ATHENA.MIT.EDU (Daniel Ankers)
Thu Oct 9 04:46:55 2014
X-Original-To: nanog@nanog.org
In-Reply-To: <20141009044007.A75E6212E0D1@rock.dv.isc.org>
Date: Thu, 9 Oct 2014 09:46:48 +0100
From: Daniel Ankers <md1clv@md1clv.com>
To: Mark Andrews <marka@isc.org>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On 9 October 2014 05:40, Mark Andrews <marka@isc.org> wrote:
>
> In message <
> 482678376.131852.1412829159356.JavaMail.zimbra@snappytelecom.net>,
> Faisal Imtiaz writes:
> > >Only short sighted ISP's hand out /56's to residential customers.
> >
> > I am curious as to why you say it is short sighted? what is the
> technical or
> > otherwise any other reasoning for such statement ?
>
> 256 is *not* a big number of subnets. By restricting the number
> of subnets residences get you restrict what developers will design
> for. Subnets don't need to be scares resource. ISP's that default to
> /56 are making them a scares resource.
My moment of clarity came when I got a /56 routed to my house and started
using it. I started off thinking that 256 was a huge number of subnets,
more than I could ever need.
What I realised was that (sticking to best practices) a /56 only allows you
one further level of delegation, and I found that to be more of a barrier
than the number of subnets. In the same way that you stop thinking "/64 is
a lot of addresses" and start thinking "/64 is a network" I find it helps
to stop thinking "/48 is 65536 subnets" and start thinking "/48 allows you
up to 4 levels of delegation."
Dan
