[0x0]

Doesn't work properly here, I get a very local IPv6, then one row of stars, then the third hop is the destination?

  % traceroute6 -w1 cv6.poinsignon.org
  traceroute to cv6.poinsignon.org (2001:bc8:3eff:c0::ff), 30 hops max, 80 byte packets
   1  2a01:x:x:x::1 (2a01:x:x:x::1)  0.794 ms  0.913 ms  0.737 ms
   2  * * *
   3  2001:bc8:3eff::1 (2001:bc8:3eff::1)  39.555 ms  39.668 ms  39.560 ms

Not sure why "traceroute6" stops at the "...::1" but "mtr" shows an equivalent 3-hop route but actually shows "...::ff" for the third and final hop? (Edit: Using "-I" with "traceroute6" makes the third and final hop also show up as "::ff". Strange that ICMP vs UDP would give different IP addresses for the final hop?)

[profmonocle]

Some middlebox in your network is probably mucking with something. Are you behind a corporate firewall?

[0x0]

No, should be a native IPv6 consumer ISP... But now that you mention it, most other IPv6 sites act like this as well. Sorry, it's probably my ISP or maybe my router. Guess I haven't been tracerouting IPv6 much since getting native IPv6 connectivity.