hmm..
Seems that every traceroute across an ATM link will result in the middle
packet being dropped. The ATM Switch nor the Router have any idea that it
is the second packet.. weird! Anyone have a clue to why that is?Tracing the route to ns2
1 206.222.97.6 44msec 44msec 44msec
2 ns2.acsi.net (206.222.97.50) 44 msec * 44 msec
I don't think it has got anything to do with ATM. I
bet you that ns2.acsi.net is a Solaris 2 box. Solaris
drops every other icmp echo if it comes too close to
the last one. This I was told is an inadvertent bug
although Sun could claim it to be a feature against
an ICMP flood attack 
Try tracerouting to sun.com (a SunOS box) and
playground.sun.com (Solaris 2). You'll see the difference.
Also try traceroute with the -q parameter greater than
the default of 3 packets each destination.
Sanjay.