Policy Statement on Address Space Allocations

Hi Randy,

> > Yes. And of course you don't care about a small side-effect: it will 
> > drive small ISP's out of business. The only way to avoid that is to do 
> > business with large ISP's such as Sprint.

> It will force folk who need only long prefixes to get their IP allocation
> from their upstream provider.

But that's not possible in the case of a multi-homed network, however small.

> > So in stead of picking on people smaller than you, go after the types 
> > that accounce 50+ routes per AS. That's the _real_ problem!

> Probably not the best metric either.  What if they are all /16s?

That would mean they connect more than a million hosts to the Internet.
There can't all that many networks that are in this position...

Let's look at a few examples.

For instance, AS 1890. They announce:

15 B, 12 C, 1 /15, 4 /16, 2 /19, 2 /22. Total: 36 routes. If they get rid of
the individual class C's and aggregate two of the /16's (they are consecutive)
that would save 13 routes, more than a third.

And AS 1103, they announce:

26 B, 12 C, 1 /9, 1 /10, 1 /11, 3 /16, 1 /17, 1 /18, 1 /19, 2 /21, 2 /22,
4 /23. Total: 55.

If they renumber the class C's and the /23's and announce 145.0.0.0/8 in
stead of 145.0.0.0/9, 145.128.0.0/10 and 145.192.0.0/11, that would save
16 routes, more than a quarter.

Then there is AS 5390:

   Network          Next Hop          Metric LocPrf Weight Path
*> 193.67.112.0/23  194.72.4.137                       100 2856 2855 5390 i
*> 194.134.0.0/22   194.72.4.137                       100 2856 2855 5390 i
*> 194.134.0.0/19   194.72.4.137                       100 2856 2855 5390 i
*> 194.134.4.0/23   194.72.4.137                       100 2856 2855 5390 i
*> 194.134.6.0      194.72.4.137                       100 2856 2855 5390 i

Without even renumbering they can save 3 out of 5 routes.

Now I hope the good people of AS 1890, AS 1103 and AS 5390 forgive me for
using their AS'es as an example, I'm sure the results will be the same for
the majority of AS'es.

So what does this tell us?

1. The routing table can be reduced by at least 5 - 10% by taking better
   advantage of aggregation opportunities.

2. Another 25% can be accomplished by renumbering individual class C's and
   very long (>20) prefixes.

Iljitsch van Beijnum
bART Internet Services