North American Network Operators Group
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Re: Generally accepted announcement sizes

  • From: Danny McPherson
  • Date: Thu Jun 22 17:32:14 2000 
The providers I'm aware that perform filtering of this sort 
normally do so based on the length of allocations from the 
RIRs (ARIN, APNIC & RIPE) within the associated address blocks.  
These polices have little to do with the RADB (Routing Arbiter 
Database) or other IRRs.

Of course, if inter-provider filtering were feasible the specific
route objects would be obtained from the RIRs and pretty much any 
correctly registered route (of a "more reasonable than today" 
length) would probably be accepted by those providers.

Consulting the allocation guidelines for those specific RIRs should 
help answer your question.  Consulting the "ISP Resources" section 
of the NANOG web server should provide useful information regarding
specific filtering policies implemented by a few ISPs.  

-danny

> Can anyone point me to a centralized resource for Tier 1 and Tier2
> providers'  accept policies?  I have found that when some of my circuits go
> down various parts of the 'Net become unreachable and I attributed that to
> the size of that announcement being a /24.  I assume that the carriers I'm
> having issue with are not using RADB as I registered all of my netblocks,