mysidia at gmail.com
Thu May 12 19:39:35 CDT 2011
On Thu, May 12, 2011 at 5:49 PM, George Bonser <gbonser at seven.com> wrote:
> Possibly the hit might be the same, but possibly not. An organization
> that requires a second /48 from their upstream might get one that can't
> be aggregated with the previous one. It is my understanding that ARIN
A very important distinction. The _immediate_ hit to the DFZ might be
the same as obtaining PI V6 space,
but the _long term_ hit to the DFZ might be much greater;
particularly if the user starts obtaining
multiple non-aggregable /48s from different sources, or obtains an
additional PI allocation later, but
keeps using the original /48.
It is a heck of a lot better for network stability that any
multi-homed user get a /32 PI,
and find that they will never need more than a /48 of it, than it is
to try to "conserve"
address bits, and require the multi-homed user stick it out with a /48.
With IPv6, bits for addressing networks are not scarce (like they
were with IPv4),
but more importantly, router FIB bits _are_ scarcer.
With IPv4, we face the certainty of address bit assignment exhaustion.
With IPv6, we face a greater risk of address bit _router_ assignment
Because every IPv6 address has 4x as many bits as an IPv4 address.
And a /48 prefix has consumes at least 2x as many bits as a /24 prefix.
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