mbone debugging: funny-looking NCSA <-> ANL mtraces

[Stuart Levy]

OK, I just tried ttl 127 -- it seems to behave the same, though.

niri 284% mtrace -t 127  141.142.220.60  140.221.8.39  224.2.177.155
Mtrace from 141.142.220.60 to 140.221.8.39 via group 224.2.177.155
Querying full reverse path... * switching to hop-by-hop:
  0  geode.mcs.anl.gov (140.221.8.39)
 -1  * * * Timed out receiving responses
Perhaps receiver 140.221.8.39 is not a member of group 224.2.177.155,
or no router local to it has a route for source 141.142.220.60,
or multicast at ttl 127 doesn't reach its last-hop router for that source