RE: ip6-localhost (::1) 2990.86 ms !H -> Why ?

From: NDSoftware (extml@ndsoftware.net)
Date: Sun Nov 18 2001 - 06:18:23 EST


> -----Original Message-----
> From: Pekka Savola [mailto:pekkas@netcore.fi]
> Sent: Sunday, November 18, 2001 12:07 PM
> To: NDSoftware
> Cc: linux-net@vger.kernel.org
> Subject: RE: ip6-localhost (::1) 2990.86 ms !H -> Why ?
>
>
> On Sun, 18 Nov 2001, NDSoftware wrote:
> > > ping6 -I eth0 fe80::2d0:70ff:fe01:811b
> >
> >
> > PING fe80::2d0:70ff:fe01:811b(fe80::2d0:70ff:fe01:811b)
> from ::1 eth0:
> > 56 data bytes
> > 64 bytes from fe80::2d0:70ff:fe01:811b: icmp_seq=1 ttl=64
> time=119 usec
> > 64 bytes from fe80::2d0:70ff:fe01:811b: icmp_seq=2 ttl=64
> time=88 usec
> > 64 bytes from fe80::2d0:70ff:fe01:811b: icmp_seq=3 ttl=64
> time=84 usec
>
> Ok.
>
> > PING fe80::a0:2434:1d91(fe80::a0:2434:1d91) from
> > fe80::2d0:70ff:fe01:811b eth0: 56 data bytes
> > >From ::1 icmp_seq=1 Destination unreachable: Address
> unreachableFrom ::1
> > icmp_seq=2 Destination unreachable: Address unreachableFrom ::1
> > icmp_seq=3 Destination unreachable: Address unreachableFrom ::1
> > icmp_seq=4 Destination unreachable: Address unreachableFrom ::1
> > icmp_seq=5 Destination unreachable: Address unreachableFrom ::1
> > icmp_seq=6 Destination unreachable: Address unreachable
> > --- fe80::a0:2434:1d91 ping statistics ---
> > 8 packets transmitted, 0 received, +6 errors, 100% loss, time 7029ms
> >
> > fe80::a0:2434:1d91 is the link adddress of eth2 of the router.
> >
> > I understand why with the same configuration Potato ping router and
> > 6bone but Woody not.
>
> It may be the connection between the two is broken.

In IPv4 it's work without problem....

>
> Capture traffic with 'tcpdump -i interface -n ip6' on both
> ends and see
> that the messages (ICMP neighbour solications, when you ping6
> the other
> end's link-local address) get through.

On router:

12:15:39.109604 0:d0:70:1:81:1b 33:33:ff:0:0:1 86dd 86:
                         6000 0000 0020 3aff 3ffe 8271 2101 0001
                         0000 0000 0000 0001 ff02 0000 0000 0000
                         0000 0001 ff00 0001 8700 d1ab 0000 0000
                         3ffe 8271 1000
12:15:40.109604 0:d0:70:1:81:1b 33:33:ff:0:0:1 86dd 86:
                         6000 0000 0020 3aff 3ffe 8271 2101 0001
                         0000 0000 0000 0001 ff02 0000 0000 0000
                         0000 0001 ff00 0001 8700 d1ab 0000 0000
                         3ffe 8271 1000
12:15:41.109604 0:d0:70:1:81:1b 33:33:ff:0:0:1 86dd 86:
                         6000 0000 0020 3aff 3ffe 8271 2101 0001
                         0000 0000 0000 0001 ff02 0000 0000 0000
                         0000 0001 ff00 0001 8700 d1ab 0000 0000
                         3ffe 8271 1000
12:15:42.109604 0:d0:70:1:81:1b 33:33:ff:0:0:1 86dd 86:
                         6000 0000 0020 3aff 3ffe 8271 2101 0001
                         0000 0000 0000 0001 ff02 0000 0000 0000
                         0000 0001 ff00 0001 8700 d1ab 0000 0000
                         3ffe 8271 1000
12:15:43.109604 0:d0:70:1:81:1b 33:33:ff:0:0:1 86dd 86:
                         6000 0000 0020 3aff 3ffe 8271 2101 0001
                         0000 0000 0000 0001 ff02 0000 0000 0000
                         0000 0001 ff00 0001 8700 d1ab 0000 0000
                         3ffe 8271 1000

On Woody:

21:38:02.882404 3ffe:8271:1000:22::1 > ff02::1:0:1: icmp6: neighbor sol:
who has 3ffe:8271:2101:1::1
21:38:03.882226 3ffe:8271:1000:22::1 > ff02::1:0:1: icmp6: neighbor sol:
who has 3ffe:8271:2101:1::1

>
> Another explanation for this is that IPv6 neighbour discovery code is
> messed up. This can happen if you take down your loopback
> interface.

ifdown lo and after:

traceroute to 6bone.net (3ffe:b00:c18:1::10) from 3ffe:8271:2101:1::1,
30 hops max, 16 byte packets
 1 * * *
 2 * * *
 3 * *

traceroute to 3ffe:8271:1000:22::1 (3ffe:8271:1000:22::1) from
3ffe:8271:2101:1::1, 30 hops max, 16 byte packets
 1 * * *
 2 *

3ffe:8271:1000:22::1 is the router.

> The problem will not be fixed by merely taking it back up, you have to
> re-add the addresses on it too. This can lead to e.g.
> eternal neighbour
> discovery loops.

Thanks very much for this help.

>
> --
> Pekka Savola "Tell me of difficulties surmounted,
> Netcore Oy not those you stumble over and fall"
> Systems. Networks. Security. -- Robert Jordan: A Crown of Swords
>
>
>
>

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