Route table growth and hardware to the filter

Bradley Urberg Carlson buc at
Sat Sep 8 17:36:51 UTC 2007

Joe Provo wrote:

> Any policing effort will require co-ordination and to be stated
> publicly (here and elsewhere) that it is a Good Thing.
> A direct cookbook provided and lots of folks will still think
> you are asking too much of them.

Some of the networks this would help may be skittish of testing the 
concept themselves.  And no Tier-2 operator would want to be perceived 
as making a cheap "hack", or of using a non-standard routing policy.   
Documenting the practice (e.g. "RFCxxxx:  filtering BGP route tables 
using RIR allocations") would help the network operator answer customer 
inquiries (and auditors' questions).

The approach could create a different kind of Tier-1/Tier-2 structure:  
default-free networks and "default-enabled networks"  ;) .  A 
default-enabled network, which lets its customers advertise long 
prefixes out of its own allocations to other ISPs, would need to 
purchase transit from default-free ISPs, or else coordinate holes in 
the filters with their default-enabled upstream.   Default-enabled 
Tier-2's would need to be clear about this limitation when selling 
transit to a BGP-speaking customer; and would be unable to use other 
default-enabled ISPs as "carrier of last resort".

-Bradley Urberg-Carlson

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