[address-policy-wg] Policy proposal: #gamma IPv6 InitialAllocation Criteria

On Sun, Apr 24, 2005 at 11:26:12AM +0200, Iljitsch van Beijnum wrote:
> At the end of the day, it's individual ISPs who decide what they  
> allow and don't allow in their routing tables. It's true that if you  
> announce a smaller block than a /32 you'll be filtered in many  
> places. However, this isn't necessarily a problem. For instance, if  
> someone in Asia sends your customer who has a /48 from you and also  
> announces this /48 to another ISP, and the Asian network filters the / 
> 48, the packet will flow towards Europe as per your /32. Then when it  
> gets to Europe, it's pretty likely that the packet will hit an ISP  
> who actually has the /48 in their routing table. After all, what's  
> allowing a few /48s from the people you get drunk with at all those  
> RIPE meetings?

The filtering out there IS a problem.

For an example what happens when you try multihoming with </32, see:
http://www.sixxs.net/tools/grh/lg/?prefix=2001:1578::/32

It's not that extreme in this case, as some/many people seem to filter
"<=/48" instead of ">/32" and /40s do pass, but in general your AS_PATHs
for the more-specifics can get VERY long. So borderline is that you have
worse to MUCH worse connectivity by announcing the more-specific than
via the aggregate, thanks to the filtering done out there.


Regards,
Daniel

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