[58100] in North American Network Operators' Group
Re: Who is announcing bogons?
daemon@ATHENA.MIT.EDU (Henry Kilmer)
Wed Apr 30 18:19:15 2003
Date: Wed, 30 Apr 2003 18:16:13 -0400
From: Henry Kilmer <hank@rem.com>
Cc: nanog@merit.edu
In-Reply-To: <200304290151.h3T1pec23500@ueno.egenius.org>
Errors-To: owner-nanog-outgoing@merit.edu
babylon@egenius.org writes:
>> Why do we expect the same ISP engineers to be better at configuring
>> negative lists or keeping them up to date?
>>
>> According to Craig Labovitz's study published at Microsoft
>> http://www.research.microsoft.com/research/pubs/view.aspx?msr_tr_id=MSR-TR-2000-74
>> 100% of the ISP's surveyed filter inbound customer route announcements.
>>
>
>Ahhh, but that was not the correct question to ask (I have not read the
>study). It is not whether ISP's filter inbound customer route
>announcements. It is how they filter them. If the customer goes and
>says I am going to announce 4.0.0.0/8 and the ISP just blindly adds
>that to the filter, we have a problem, but the ISP did answer that
>question truthfully. They are filtering.
Many ISPs use AS path filters for customers with a large number of
announcements. Some implement netblock filters that are not exact
matches. Both of these are examples where the ISP would honestly say
they filter but holes exist.
-Hank
