Criteria for initial PA Allocation

Hi,

(originally I did not really want to participate in this discussion,
as much of it has already been said in the last LIR-WG meeting).

One thing got me thinking,though:

On Tue, May 22, 2001 at 02:16:32PM +0100, Carlos Friacas wrote:
> /22 is a much more reasonable value by my view... 

Be careful what you are asking for.

If we assume that minimum allocation size will go down to a /22, and
further assume that one fourth of the full IPv4 address range will
subsequently be handed out *and announced* as /22's, this means we
will see ( 1/4 * 2^22 ) = 1048576 /22's announced in the global BGP
table.  That's over a million BGP routing table entries.

This will have a significant effect on BGP routing stability and
also on the costs of global routing - you need a Gig of RAM in all
the BGP routers (on distributed architectures, more than that).  The
CPU power required to handle a flap of a major line in a timely fashion
(to keep BGP convergence times low) will be horrendous.

Also, it can be assumed that in this case, the global topology will
become complex enough so that most of the time many of the smaller
ASes won't be reachable anyway due to problems "on the way".

I think this is something I do NOT want to see.


So, what is my conclusion?  I estimate that while IPv4 address exhaustion
is going to be a problem (which IPv6 will solve), the routing topology 
will cause major problems *sooner* than IPv4 runs out, and we should
do something against this.  By this, I mean:

 - strongly encourage people to renumber from historic PI space to
   PA space from their ISPs network block (and return the PI space
   to the RIRs, to be aggregated)

 - stop handing out PI space

 - discourage "end users" from using multihoming with globally visible
   address space (there are other ways, like "get multiple uplinks
   to different POPs of the same ISP, and have them sign a SLA that
   will get you 99.9% reachability or money back").

 - discourage people from becoming LIR if that's only to get "portable"
   address space, with no intention of handing PA space out to customers.

Yes, this might sound a bit harsh, but I'm *really* worried about
routeability and reachability of anything in the next couple of years.

Now go and flame me... :-)

Gert Doering
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