[100847] in North American Network Operators' Group
RE: RIR filtering & Level3
daemon@ATHENA.MIT.EDU (Eric Van Tol)
Thu Nov 15 09:22:54 2007
Date: Thu, 15 Nov 2007 09:20:58 -0500
In-Reply-To: <473BB21B.10009@justinshore.com>
From: "Eric Van Tol" <eric@atlantech.net>
To: <nanog@merit.edu>
Errors-To: owner-nanog@merit.edu
> Are any other L3 customers seeing the large number of /25 and smaller=20
> routes from L3? I'm seeing almost 2500 of these routes in=20
> 4/8, some but=20
> not as many in 8/8 and still more in L3's non-US allocations.=20
I am pretty sure that L3 allows anything up to a /28 (they used to,
anyway, from my old notes on their policy) on customer peering sessions.
It may be /25 now. Non-peering sessions explicitly disallow anything
longer than a /24, according to 'whois -h whois.radb.net as3356':
remarks: The following import actions are common to every
remarks: Level 3 non-customer peering session:
...
remarks: - Prefixes shorter than /8 or longer than /24 are
remarks: not announced.
Global Crossing does the same, as do many other providers. Best thing
is to just deny anything longer than /24 at your border if you do not
have multiple egress points to this one provider. To be sure they are
customers, check the community string to see if it is 3356:123.
-evt
