IPv6 ND on PPC hardware

IPv6 ND on PPC hardware

[Marco d'Itri]

I do not understand why ND is not working. Is my configuration wrong or
I have exposed a kernel bug?
When I try to ping another host on the LAN it usually works the first
time, and then stops working because the other host does not reply to
ND requests. Everything works again if I switch the remote interface
in promiscuous mode.

erode:/# ip -6 ad
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    inet6 ::1/128 scope host
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
    inet6 3ffe:1001:210:16::3/64 scope global
    inet6 3ffe:8271:a040:16::3/64 scope global
    inet6 3ffe:8171:10:16::3/64 scope global
    inet6 fe80::204:acff:fe97:7130/10 scope link
erode:/# ip -6 ro
3ffe:1001:210:16::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
3ffe:8171:10:16::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
3ffe:8271:a040:16::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
2000::/3 via 3ffe:1001:210:16::1 dev eth0  metric 1024  mtu 1500 advmss 1440
fe80::/10 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
ff00::/8 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
unreachable default dev lo  metric -1  error -101
erode:/# uname -a
Linux erode 2.4.19-rc1 #1 Sat Jun 29 15:05:41 CEST 2002 ppc unknown

The other host has a similar configuration.

Seen from a third host (i386, which appears to work) on the same LAN:

16:23:22.818468 erode.bofh.it > ff02::1:ff00:1: icmp6: neighbor sol: who has attila.bofh.it(src lladdr: 0:4:ac:97:71:30) (len 32, hlim 255)
16:23:23.814589 erode.bofh.it > ff02::1:ff00:1: icmp6: neighbor sol: who has attila.bofh.it(src lladdr: 0:4:ac:97:71:30) (len 32, hlim 255)
16:23:24.814834 erode.bofh.it > ff02::1:ff00:1: icmp6: neighbor sol: who has attila.bofh.it(src lladdr: 0:4:ac:97:71:30) (len 32, hlim 255)
16:23:25.844675 erode.bofh.it > ff02::1:ff00:1: icmp6: neighbor sol: who has attila.bofh.it(src lladdr: 0:4:ac:97:71:30) (len 32, hlim 255)

--
ciao,
Marco

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Re: IPv6 ND on PPC hardware

[Noah Meyerhans]

On Tue, Jul 02, 2002 at 01:36:42PM +0200, Marco d'Itri wrote:
> I do not understand why ND is not working. Is my configuration wrong or
> I have exposed a kernel bug?

It is likely a problem with broken multicast support.

> When I try to ping another host on the LAN it usually works the first
> time, and then stops working because the other host does not reply to
> ND requests. Everything works again if I switch the remote interface
> in promiscuous mode.

This sounds even more likely to be broken multicast support.  Do you see
the proper behavior if you enable allmulti on your interface, rather
than promiscuous mode?

A driver bug could be what's causing multicast not to work.  That's
probably most likely, though there also could be a problem with
hardware.

noah

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Re: IPv6 ND on PPC hardware

[Noah Meyerhans]

On Wed, Jul 03, 2002 at 02:39:31AM +0200, Marco d'Itri wrote:
> Yes, allmulti fixes it. Where else should I look?

Well, I definitely think you've found a card with broken multicast
support.

> 00:0c.0 Ethernet controller: Advanced Micro Devices [AMD] 79c970 [PCnet LANCE] (rev 26)

You should probably contact the author of the driver and see if they
have anything to say about it.  Many drivers don't implement multicast
correctly because the author doesn't use it and therefore can't test it.

> I do not think this is a hardware problem because the same thing happens
> on two twin machines (a couple of IBM B50).

What I meant by "hardware problem" is not a problem with your specific
card, but a problem with the chipset itself not doing the right thing.
Multicast support must be present and working in the hardware in order
for it to work in software.  I don't know how common this type of
problem is, and I don't know if there's a way to get around it in
software.

noah

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