[arin-ppml] Opposed to 2010-9 and 2010-12

William Herrin bill at herrin.us
Wed Oct 13 07:23:17 EDT 2010

On Tue, Oct 12, 2010 at 11:55 PM, Mark Andrews <marka at isc.org> wrote:
> There is a increadable amount of bad information being spouted here.
> If you have a 2 disjoint /16's spead over, multiple pops, then you
> will have 2 6rd prefixes in use both with a IPv4MaskLen of 16.  Only
> one of these will be handed out to a specific customer.  If you are
> handing out /56's then the 6rdPrefixLen would be 40.  Each of these
> 6rd prefixes would be a /40.

Hi Mark,

If you have a dozen IPv4 prefixes or more (as many ISPs do) you're not
going to maintain a dozen or more 6rd prefixes. Instead, you're going
to map a full 32 bits into a single 6rd prefix. That's the _practical
reality_ of an operational network, regardless of what 6rd's designers
intended. If you don't map 32 bits, you'll at least map your entire
CGN space in, and that takes a few bits all by itself.

The discussion has been focused on those folks for whom 6rd is not
useful unless the full 32 bits are mapped. This is not surprising
since any organization small enough to maintain shorter mappings has
no trouble fitting 6rd into their original /32 allocation and thus
doesn't need new policy.

Bill Herrin

William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004

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