Closure?

[J. Scott Marcus]

At 16:14 01/26/2001 +0000, bmanning at vacation.karoshi.com wrote:
>
>	This is to remind you that ARIN is still holding out on accepting the
>IAB/IESG recommendations for inital IPv6 delegation/allocation sizes. There
>was some lively discussion at the last mtg but the concerns generally came
>down to... "this makes me nervous and I don't understand it all to well."
>Yes, there are operational concerns but quite frankly, the number of people
>in the ARIN region that are able/willing to explore IPv6 seems to be either
>very small, not willing to share experiences, or are happy with the 6bone
>delegations.  ARIN has pretty much removed the barriers to entry with the
>zero-cost delegation policy in place.  
>
>	Unless a viable counter proposal or modification to the existing
>IAB/IESG proposal that has been accepted by RIPE and APNIC, I'm going 
>to recommend to the ARIN council that silence is consent and ARIN should
>adopt the IAB/IESG proposal for a /48 being the default delegation size,
>subject to review, based on operational experience.

As you may recall, I was one of the people who spoke up after Brian's talk
at our last Public Policy meeting.

Actually, I support the IAB/IESG recommendation, in general.  There are two
aspects that trouble me, and I would like to see these made clear to the
IAB and IESG:

1) the recommendation is too glib in a number of its assumptions (see below).

2) the IAB and IESG had jolly well better remember that, if we do this,
there are few if any additional bits to be given away!



As far as assumptions:  The recommendation states that the allocation
efficiency for the 45 usable high order bits needs to remain above 0.22 in
order to provide a /48 to everyone expected to be on the planet in 2050,
and that the telephone system already exceeds this.

>  - RFC 1715 defines an "H ratio" based on experience in address space
>    assignment in various networks.  Applied to a 45 bit address space,
>    and projecting a world population of 10.7 billion by 2050 (see
>    http://www.popin.org/pop1998/), the required assignment efficiency
>    is log_10(1.07*10^10) / 45 = 0.22.  This is less than the
>    efficiencies of telephone numbers and DECnetIV or IPv4 addresses
>    shown in RFC 1715, i.e., gives no grounds for concern.

In fact, it probably IS plenty.  But it is important to remember the
implication:  That addresses within the initial 45 usable bits will be
assigned fairly densely.  The H ratio for the RIGHTHAND 80 bits of the IPv6
address is approximately zero -- not a sustainable example for the LEFTHAND
bits to follow.

Some IPv6 proponents like to claim that the protocol could uniquely address
every electron in the universe.  It's important to remember that the
EFFECTIVE capacity of IPv6 reflects only 45 bits of addressability.  The
other 83 have already been wasted by the current recommendations.

Are the remaining 45 bits enough?  Yes, probably.  But we need to be honest
with ourselves.



>  - We are highly confident in the validity of this analysis, based on
>    experience with IPv4 and several other address spaces, and on
>    extremely ambitious scaling goals for the Internet amounting to an
>    80 bit address space *per person*.  Even so, being acutely aware of
>    the history of under-estimating demand, we have reserved more than
>    85% of the address space (i.e., the bulk of the space not under the
>    Aggregatable Global Unicast Address (TLA) format prefix).
>    Therefore, if the analysis does one day turn out to be wrong, our
>    successors will still have the option of imposing much more
>    restrictive allocation policies on the remaining 85%.

If we reach this scenario within our childrens' lifetime, we will have failed.

The assumption that this migration entails only the implementation of new
allocation policies is flawed.  Much of the deployed gear -- perhaps most
of it -- will break if this happens.



Again, the recommendation is probably workable.  I am worried about the
underlying overconfidence.

My two cents,
- Scott