If those interim hops are IPv4 only nodes part of 6/PE there could be a few things going on here.
1) Juniper u-RPF for family inet6 drops the mapped-v4-v6 source packets generated by a P/PE router 2) FreeBSD (8.2 at least) doesn't seem to like mapped-v4-v6 source packets with its default traceroute (same for mtr on FreeBSD) (tcpdump will show you the packets coming back, the freebsd traceroute6 seems to have a few unresolved bugs.. you need to force -w 1 as well likely) 3) If end-to-end connectivity works, Workarounds: the IPv4 only P/PE device should have some sort of IPv6 address placed on transit interfaces to allow TTL expired to be sourced from something capable (this IP doesn't need to be able to be reached/routed to that interface, just exist). I spent a lot of time looking at a similar problem and it ended up being a combination of #1 & #2 above. You will see this problem across The AT&T and Cogent networks in my experience. - Jared On Jul 6, 2011, at 10:39 PM, Mark Andrews wrote: > > The below has been on going for over a week (yes it has been reported to HE) > and the IETF). > > Not returning time exceeded really make debugging routing problems hard. > > Mark > > traceroute6 -lI www.ietf.org > traceroute6 to www.ietf.org (2001:1890:1112:1::1e) from > 2001:470:1f00:ffff::5a1, 64 hops max, 16 byte packets > 1 dviscorg.tunnel.tserv1.fmt.ipv6.he.net (2001:470:1f00:ffff::5a0) 172.669 > ms 182.219 ms 170.424 ms > 2 2001:470:0:1f::1 (2001:470:0:1f::1) 178.128 ms 171.926 ms 174.877 ms > 3 gige-g4-8.core1.fmt2.he.net (2001:470:0:2d::2) 172.193 ms 171.265 ms > 171.221 ms > 4 10gigabitethernet6-4.core1.lax1.he.net (2001:470:0:18d::2) 198.338 ms > 190.680 ms 182.413 ms > 5 10gigabitethernet1-3.core1.lax2.he.net (2001:470:0:72::2) 178.924 ms > 189.431 ms 180.538 ms > 6 2001:470:0:1e6::2 (2001:470:0:1e6::2) 181.137 ms 179.374 ms 182.321 ms > 7 * * * > 8 * * * > 9 * * * > 10 * * * > 11 * * * > 12 2001:1890:1fff:ffff::1 (2001:1890:1fff:ffff::1) 262.713 ms * * > 13 * * * > 14 * * * > 15 * * * > 16 * * * > 17 * * * > 18 * * * > 19 * * * > 20 * * * > 21 * * * > 22 * * * > 23 * * * > 24 * * * > 25 * * * > 26 * * * > 27 * * * > 28 * * * > > -- > Mark Andrews, ISC > 1 Seymour St., Dundas Valley, NSW 2117, Australia > PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
