Aggregation & path information [was: 200K prefixes - Weekly Routing Table Report]

Patrick W. Gilmore patrick at
Fri Oct 13 19:14:38 UTC 2006

On Oct 13, 2006, at 3:04 PM, Philip Smith wrote:

> I was kinda hoping that it would hit 200K on Tuesday, then I could  
> have
> added the announcement to my aggregation recommendations lightning  
> talk!
> ;-) Bit sad that a 200K table can be aggregated down to 109k prefixes
> with no loss of path information (in my BGP table view).

I find this interesting.

Obviously the table contains kruft.  But I know we could not shrink  
it to 109K prefixes without losing something from where I sit.  Are  
you sure there's no additional path info?

If there were a way to guarantee certain prefixes are completely  
superfluous, we could make a hit list of just those providers, then  
ridicule or filter or cause them pain in some way to make them stop  
causing us pain.  I haven't seen that type of report posted publicly,  
just "this CIDR can fit in that one" without actual guarantees that  
_paths_ are equivalent.  (Usually the origin AS is matched as well as  
the prefixes, but that's not the same as guaranteeing the path is  

Of course, this is non-trivial.  But then neither is aggregating the  
global table. :)


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