IPv6 Default Allocation - What size allocation are you giving out

Thu Oct 9 08:46:48 UTC 2014

On 9 October 2014 05:40, Mark Andrews <marka at isc.org> wrote:

>
> In message <
> 482678376.131852.1412829159356.JavaMail.zimbra at 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