You may cross check return path to XO if you have access to any sever on DTAG or from there looking glass if available. In many cases sudden latency spike comes because of incorrect return path. Hope this will help. (Sent from my mobile device) Anurag Bhatia http://anuragbhatia.com On May 4, 2012 9:32 PM, "Tim Durack" <tdurack@gmail.com> wrote:

Trying to troubleshoot packet loss from NYC to DEU. Traceroute shows:

tdurack@2ua82715mg:~$ traceroute -I 194.25.250.73 traceroute to 194.25.250.73 (194.25.250.73), 30 hops max, 60 byte packets

<snip> 4 216.55.2.85 (216.55.2.85) 1.694 ms 1.698 ms 1.698 ms 5 vb1010.rar3.nyc-ny.us.xo.net (216.156.0.17) 4.788 ms 4.792 ms 4.791 ms 6 207.88.14.178.ptr.us.xo.net (207.88.14.178) 1.684 ms 1.461 ms 1.452 ms 7 62.157.250.245 (62.157.250.245) 40.457 ms 42.980 ms 42.982 ms 8 hh-eb3-i.HH.DE.NET.DTAG.DE (62.154.32.134) 129.417 ms * 129.422 ms 9 194.25.250.73 (194.25.250.73) 139.501 ms 136.192 ms 139.236 ms

Packet loss of approx. 20% affects hops 7 and 8, along with end host 9. Loss appears to be data-plane, not control-plane rate limiting. Affected customer confirms this too :-)

62.157.250.245 is in Deutsche Telekom address spaces, so I'm guessing this is either a DTAG problem or an issue between XO and DTAG.

I have a ticket open with XO, but I'm having a hard time figuring out what is ~40ms away from NYC on a path to DEU. Any idea what the physical path is?

-- Tim:>