request for help in finding a blackhole

[Drake Wilson]

Quoth Jogi Hofmüller <jogi at mur.at>, on 2010-05-04 19:26:27 +0200:
> There is a tunnel between hops 2 and 3 where MTU drops to 1476 (PMTUD
> working correctly).  Nevertheless, the largest pakets I can get over the
> wire - all the way up to he.net - have 1450 bytes.

As a data point, I can get pings of 1410 IPv6 payload bytes between
drache.begriffli.ch (2001:470:1f0f:c9::2), which is behind an HE 6in4
tunnel, and www.mur.at (2a02:3e0::21:80).  Larger than 1410 bytes gets
no response.  Local MTU between drache and zwischenschaltung is 1472.

traceroute to www.mur.at (2a02:3e0::21:80) from 2001:470:1f0f:c9::2, 30 hops max, 60 byte packets
 1  zwischenschaltung.begriffli.ch (2001:470:1f0f:c9::1)  0.472 ms  0.468 ms  0.416 ms 
 2  begrifflich.tunnel.tserv8.dal1.ipv6.he.net (2001:470:1f0e:c9::1)  16.509 ms  16.714 ms  15.672 ms 
 3  gige-g2-14.core1.dal1.ipv6.he.net (2001:470:0:78::1)  18.130 ms  20.807 ms  22.780 ms 
 4  10gigabitethernet1-4.core1.chi1.he.net (2001:470:0:c4::1)  46.684 ms  46.217 ms  41.291 ms 
 5  ibx-chi.ip6.tiscali.net (2001:504:0:4::3257:1)  46.927 ms  43.989 ms  41.354 ms 
 6  xe-2-1-0.nyc20.ip6.tinet.net (2001:668:0:2::1:1481)  80.681 ms  79.285 ms  76.807 ms 
 7  xe-5-2-0.lon11.ip6.tinet.net (2001:668:0:2::1:1072)  159.303 ms  156.890 ms  *
 8  xe-0-3-0.lon10.ip6.tinet.net (2001:668:0:2::1:1622)  159.263 ms  156.882 ms  154.935 ms 
 9  * * *         
10  * * *         
11  Aconet.tu-637.sar1.Amsterdam1.Level3.net (2001:1900:5:2::a2)  226.214 ms  224.457 ms  222.389 ms 
12  2001:628::a089:0:1 (2001:628::a089:0:1)  230.819 ms  230.740 ms  225.948 ms 
13  www.mur.at (2a02:3e0::21:80)  231.697 ms  229.288 ms  227.128 ms 

   ---> Drake Wilson