who gets a /32 [Re: IPV6 renumbering painless?]

Tue Nov 30 12:14:32 UTC 2004

On 23-nov-04, at 11:09, Elmar K. Bins wrote:

>> Well, suppose we know 212/8 is used in Europe. A network that is
>> present in say, North America and Europe then has the routers in 
>> Europe
>> that talk to the routers in America filter out all 212/8 more 
>> specifics
>> and only announce the aggregate instead. In the simple version this
>> only works if there is full interconnection for all 212/8 destination
>> in Europe.

> And if everyone gives transit to anyone. Ideal world.

Actually everyone giving everyone transit is far from ideal. We've seen 
this happen in IPv6, with poor performance as a result. The trouble is 
that the destination of the traffic can do very little to improve this 
even if good connectivity is also present.

But that's not what I'm saying anyway. If aggregates are only used 
within ASes and not communicated to other ASes, the macro view will 
stay the same. We just remove information in places where it has no 
added value. For example, someone in Los Angeles really doesn't care 
whether a packet goes to Darmstadt or Hannover. All they care about is 
that the packets move to the east.

The correlation between network topology and geography doesn't have to 
be perfect. The number of routing table entries saved corresponds to 
the level of topology/geo correlation. Anything from 50% and up would 
be worthwhile, IMO.