Global Blackhole Service

Matthew Moyle-Croft mmc at
Sun Feb 15 00:02:35 UTC 2009

Florian Weimer wrote:
> If you want to run a public exchange point, you need to solve the same 
> announcement validation problem. Multiple organizations appear to do 
> it successfully, so it can't be that difficult.
How exactly do you do "validation"?   If I give you a list of ASes and 
prefixes, what can you do to validate that they're ones I can actually 
announce on behalf of someone else?   I can put whatever I want in an 
AS-SET (etc) pretty much.  How do you actually check that I have the 
right relationship with a customer (or customer of a customer of a 
customer etc)?  

To put it into context - the approach of stuffing other people's ASes in 
a path to prevent them learning it is wide spread, especially in Asia - 
I've seen AS-SETs with all sorts of Tier1/2 ASes even though I know that 
they have no transit relationship with them!


Matthew Moyle-Croft - Internode/Agile - Networks
Level 4, 150 Grenfell Street, Adelaide, SA 5000 Australia
Email: mmc at  Web:
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