XO/AS2828 -> Cogent/AS174 blackholing

Tore Anderson tore.anderson at redpill-linpro.com
Mon Nov 22 03:59:18 CST 2010


Hi list,

I'm seeing blackholing on my inbound traffic from XO and their
downstreams (notably CNN) via Cogent.  Prepending towards Cogent changes
my inbound path from 2828 174 39029 to 2828 3549 3292 39029 and it
works fine, even though the outbound path is still via Cogent:

tore at cr3> traceroute 2610:18::3050 wait 2 no-resolve
traceroute6 to 2610:18::3050 (2610:18::3050) from 2a02:c0:1000:1::2, 64 hops max, 12 byte packets
 1  2a02:c0:1000:1::1  0.822 ms  1.290 ms  0.355 ms
 2  2001:978:2:30::1  0.465 ms  0.477 ms  0.395 ms
 3  * * *
 4  * * *
 5  2001:7f8:4::ae:1  582.740 ms *  82.538 ms
 6  * * *
 7  2001:504:f::c  106.967 ms  109.421 ms  107.129 ms
 8  2001:550:3::11e  121.969 ms  103.842 ms  112.119 ms
 9  2610:18::3050  143.462 ms  142.717 ms  145.179 ms

2610:18::3050 is the first hop in XO's network on the way to
ipv6.cnn.com.  If I stop prepending towards Cogent, 2001:550:3::11e is
the last hop that gives me any replies.  So it appears my announcements
reach XO, but the packets gets lost somewhere along the line.  Cogent
told me they found nothing wrong with their end of the peering.  Anyone
in or behind XO with the same problem?  2001:978:1:326::2 is an example
of a router in Cogent's network (in Stockholm) that should respond to
pings if everything works fine.

It seems like the problem happens with Cogent's own routes as well, as
neither 2610:18::3050 nor 2620:0:2200:8:8888:8888:8888:8901
(ipv6.cnn.com) get any replies when pinging from Cogent's looking glass.

Best regards,
-- 
Tore Anderson
Redpill Linpro AS - http://www.redpill-linpro.com
Tel: +47 21 54 41 27




More information about the NANOG mailing list