How long is reasonable to fix a routing issue in IPv6?

Thu Jul 7 06:14:26 UTC 2011

In message <9634AA8C-C8FD-4AFE-A888-82C9C326636D at puck.nether.net>, Jared Mauch w
rites:
> 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)

I see nothing in tcpdump other than the outgoing traffic and the replies
already noted.

> 3) If end-to-end connectivity works,=20
> 
> 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.

The path is going through AT&T.

> - Jared
> 
> On Jul 6, 2011, at 10:39 PM, Mark Andrews wrote:
> 
> >=20
> > The below has been on going for over a week (yes it has been reported =
> to HE)
> > and the IETF).
> >=20
> > Not returning time exceeded really make debugging routing problems =
> hard.
> >=20
> > Mark
> >=20
> > 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  * * *
> >=20
> > --=20
> > Mark Andrews, ISC
> > 1 Seymour St., Dundas Valley, NSW 2117, Australia
> > PHONE:	+61 2 9871 4742		         INTERNET: marka at isc.org
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org