[ppml] Legacy /24s

William Herrin arin-contact at dirtside.com
Sat Sep 1 14:40:25 EDT 2007

On 9/1/07, Leo Bicknell <bicknell at ufp.org> wrote:
> So individuals and small businesses should be allowed to eat up
> routing slots in tens of thousands of routers worldwide collectively
> costing ISP's millions of dollars in capital, if and only if they
> were smart enough to get an "early" IPv4 allocation?


Lets put some numbers to this so that we're arguing facts rather than opinions.

There are 233,000 IPv4 routes and a little under 1000 IPv6 routes in
the default-free zone (DFZ) today.

10%-30% of the routers in the DFZ today have a hard limit between
244,000 and 260,000 IPv4 routes or half that number of IPv6 routes.
When the limit is reached within the next few months, those routers
will experience various degrees of falling over dead. Upgrading these
routers to accomodate 1M IPv4 or 500k IPv6 routes will cost
$30,000-$150,000 each.

In the more general case, these routers have to be upgraded every 3-5 years.

The number of routes and ASes in the DFZ implies that there are
somewhere between 200,000 and 300,000 routers in the DFZ.

Lets start with the low numbers. If its $30k to put 233k routes in the
DFZ then each route in each router costs around 13 cents. Times 200k
routers offers an aggregate worldwide cost of $26,000 to announce an
IPv4 route. The IPv6 routes consume twice the capacity in the router,
so that means the worldwide cost of announcing an IPv6 prefix is
$52,000. On a 3-year upgrade cycle that's an annual attributable cost
of $17,300 per prefix.

Lets try the high numbers. $150k to handle 500,000 IPv6 routes = 30
cents per route. Times 300k routers = $90l. Divide by a 5 year upgrade
cycle = an annual attributable cost of $18,000 per prefix.

While this is not a thorough cost analysis, its reasonable for
ballparking. I can say with an acceptable degree of confidence that
the worldwide attributable cost of announcing one IPv6 prefix is
between $17k and $18k per year.

So, with any proposal to expand the availability of IPv6 PI, the
question that should be asked is: "Does the proposed use in the
expansion justify asking the rest of the world to pay $17k?"

My opinion is that in the case of a multihomed content provider, the
answer is yes. Why should he receive poor treatment in IPv6 merely
because his mechanism for providing content was efficient enough to
require only a few IP addresses? If you're willing to pay the prices
that the network operators require to be mulithomed (whatever that
happens to be) then you should be eligible for the necessary IPv6 PI
assignment. That's just how the Internet functions and the $17k is a
cost of doing business.

In the case of single-homed folks who just want to avoid renumbering
hassles, I think you'd need an awfully large number of computers
before the renumbering hassle adds up to $17k/yr. Many many computers.

As for the folks who want to weasel out of the $100/yr annual
maintenance fee for an IPv6 PI assignment, I would ask why anyone
should take your request seriously when you're simultaneously asking
the rest of the world to spend $17,000/yr on your behalf.

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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