Re: NAT66 and the subscriber prefix length

From: Crist Clark (no email)
Date: Tue Nov 18 2008 - 14:33:01 EST

  • Next message: Tim Durack: "Re: NAT66 and the subscriber prefix length"

    >>> On 11/18/2008 at 11:03 AM, "Tim Durack" <> wrote:
    > On Fri, Nov 14, 2008 at 2:28 PM, Mikael Abrahamsson <>wrote:
    >> On Fri, 14 Nov 2008, wrote:
    >> Not long ago, ARIN changed the IPv6 policy so that
    >>> residential subscribers could be issued with a /56
    >>> instead of the normal /48 assignment. This was done
    >>> so that ISPs with large numbers of subscriber sites
    >>> would not exhaust their /32 (or larger) allocations
    >>> too soon. Since these ISPs are allowed to assign
    >>> a /56 to residential subscriber sites, their initial
    >>> IPv6 allocation will last a lot longer and they won't
    >>> have to apply for an additional allocation while
    >>> everyone is getting up to speed with an IPv6 Internet.
    >> We returned our /32 for a /25 (with /22 being reserved) and current plan is
    >> to hand out /48s to everybody (unless they need even more space, then
    >> they'll have to apply).
    >> So, doing /56 to end users just because you happen to have a /32 right now
    >> sounds like a bad plan, it doesn't take that many hours to get a larger
    >> space if you can justify it (which wasn't that hard for us).
    >> We received our /32 (as a /35 I think) back in 2000 or so, policy has
    >> changed since then, with RIPE it's not that hard to get a much larger space
    >> with a long term growth plan. My hope is that we'll make do with this /22
    >> space for at least 5-10 years (67 million customer /48s is quite a lot),
    >> unless something really big happens, and then we'll just have to get an even
    >> larger space.
    >> So message should be that /48 to end users is the way to go, and this
    >> should suit residential and SME market without any additional administrative
    >> overhead depending on customer size.
    >> --
    >> Mikael Abrahamsson email:
    > This raises questions for me: we are a mixed enterprise/campus environment.
    > Recently got a /45 assigned, so we have a /48 per site (it was some work to
    > convince ARIN that fancy subnetting to make a /46 stretch a little further
    > made no sense.)

    A /45? I thought all allocations were on nibble borders for
    IP6.ARPA considerations.

  • Next message: Tim Durack: "Re: NAT66 and the subscriber prefix length"

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