[142570] in North American Network Operators' Group
Re: How long is reasonable to fix a routing issue in IPv6?
daemon@ATHENA.MIT.EDU (Jared Mauch)
Wed Jul 6 23:49:45 2011
From: Jared Mauch <jared@puck.nether.net>
In-Reply-To: <20110707023931.B91E111920D3@drugs.dv.isc.org>
Date: Wed, 6 Jul 2011 23:48:41 -0400
To: Mark Andrews <marka@isc.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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,=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.
- 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@isc.org
