Peer Filtering

Paul Stewart pstewart at
Tue Feb 3 11:12:20 UTC 2009

That was one of our biggest worries.... people make mistakes and route
leaks happen.....

The unfortunate part we're faced with now is that we have several
downstream customers who are multihomed.  Because we're filtering out
some of the prefixes that are not in an IRR, those routes are not nearly
as attractive downstream giving the other carrier involved an
advantage..... I can see this is where convenience/economics start to
kick in ;(

Appreciate all the replies on-list and off-list - it seems there is
about 80/20 split on people doing prefix-list vs IRR filtering....


-----Original Message-----
From: Martin Barry [mailto:marty at] 
Sent: February 2, 2009 10:22 PM
To: nanog at
Subject: Re: Peer Filtering

$quoted_author = "John van Oppen" ;
> Here in the US we don't bother, max-prefix covers it...   It seems
> US originated prefixes are rather sporadically entered into the
> DBs.
...and you are not worried about someone leaking a subset of routes?

I understand that most failure cases would trigger a max-prefix but a
could allow just enough leakage to not hit max-prefix and yet still make
something "important" unreachable.


with usenet gone, we just don't teach our kids entertainment-level
any more. --Paul Vixie



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