Are any other L3 customers seeing the large number of /25 and smaller routes from L3? I'm seeing almost 2500 of these routes in 4/8, some but not as many in 8/8 and still more in L3's non-US allocations.
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