prefix filtering per IRR - practices

Michael Hallgren m.hallgren at
Fri Nov 22 17:37:21 UTC 2013

Le 22/11/2013 17:57, Chris Rogers a écrit :
> From my experience, networks that are capable of filtering from IRR objects
> generally filter for exact routes, meaning no "le 24". 


Are you sure? My experience is, with a small number of exceptions,
that "le 24" ('route' or 'route-set,' sometimes in relation with "is in
AS-set of peer") is an often used policy. Maybe it depends on what
kind of networks one's looking at? 


> While I've always
> found networks to be set in their ways, I know some people that have
> managed to get their filters changed to allow longer prefixes without
> needing additional objects.
> But ultimately, it does help prevent the leaking of internal routes.
> -Chris
> On Fri, Nov 22, 2013 at 6:55 AM, Frank Habicht <geier at> wrote:
>> Hi,
>> I have a question regarding what's the most common practice [1]
>> for transit ASs to filter prefixes from their BGP customers
>> when using IRR data. (which of course everyone does...)
>> Would many/most/all/none :
>> a) accept only the prefixes listed in route objects
>> or
>> b) accept these and anything "upto /24" (or "le 24")
>> I was hoping / assuming the latter but I start getting a different
>> impression.
>> Yep, and apart from the current status, the tendency would be of interest.
>> Thanks,
>> Frank
>> [1] after "my network, my rules"

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