ipv6 debugging

ipv6 debugging

[Ferenc Wagner]

Hi,

I'm kindly asking for some debugging tips with the following problem:
a machine is running Linux 2.6.24.2, several 802.1q VLAN-s over
active/backup bonding over two physical interfaces.  Everything is
allright, except for after a reboot, there's no IPv6, while IPv4
works.  The router's ARP(6) table is empty, the machine doesn't answer
ping6.  However, if I start tcpdump -i bond0 ip6, everything is
allright again.  There are some indications that after some period
without IPv6 traffic, the same can happen again.  Are there known
issues which can exhibit themselves like this?  Other very similar
setups don't show this erratic behaviour.

I know that the above doesn't give a fully detailed picture, but
thought that I'd better ask before taking the setup into pieces.
-- 
Thanks for your thoughts,
Feri.

Re: ipv6 debugging

[Jorge Boncompte [DTI2]]

    This sounds to me like the same problem that I was having with OSPF, I 
think ARP(6) uses multicast ethernet address too. Can you try if the patch 
below, that I sent Patrick McHardy some days ago, fixes your problem?

    Regards,

    Jorge
---
    Hi Patrick,

    Commit a0a400d79e3dd7843e7e81baa3ef2957bdc292d0 from you
    introduced a new field "da_synced" to struct dev_addr_list that is
    not properly initialized to 0. So when any of the current users (8021q,
    macvlan, mac80211) calls dev_mc_sync/unsync they mess the address
    list for both devices.

    The attached patch fixed it for me and avoid future problems.

    Regards,

    Jorge

Signed-off-by: Jorge Boncompte [DTI2] jorge@dti2.net
---
diff --git a/net/core/dev.c b/net/core/dev.c
index 9549417..f1b6708 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2900,7 +2900,7 @@ int __dev_addr_add(struct dev_addr_list **list, int
*count,
                }
        }

-       da = kmalloc(sizeof(*da), GFP_ATOMIC);
+       da = kzalloc(sizeof(*da), GFP_ATOMIC);
        if (da == NULL)
                return -ENOMEM;
        memcpy(da->da_addr, addr, alen);

----- Original Message ----- 
From: "Ferenc Wagner" <wferi@niif.hu>
To: <netdev@vger.kernel.org>
Sent: Monday, February 18, 2008 3:06 PM
Subject: ipv6 debugging


> Hi,
>
> I'm kindly asking for some debugging tips with the following problem:
> a machine is running Linux 2.6.24.2, several 802.1q VLAN-s over
> active/backup bonding over two physical interfaces.  Everything is
> allright, except for after a reboot, there's no IPv6, while IPv4
> works.  The router's ARP(6) table is empty, the machine doesn't answer
> ping6.  However, if I start tcpdump -i bond0 ip6, everything is
> allright again.  There are some indications that after some period
> without IPv6 traffic, the same can happen again.  Are there known
> issues which can exhibit themselves like this?  Other very similar
> setups don't show this erratic behaviour.
>
> I know that the above doesn't give a fully detailed picture, but
> thought that I'd better ask before taking the setup into pieces.
> -- 
> Thanks for your thoughts,
> Feri.
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: ipv6 debugging

[Ferenc Wagner]

"Jorge Boncompte [DTI2]" <jorge@dti2.net> writes:

> Ferenc Wagner <wferi@niif.hu> writes:
>
>> I'm kindly asking for some debugging tips with the following problem:
>> a machine is running Linux 2.6.24.2, several 802.1q VLAN-s over
>> active/backup bonding over two physical interfaces.  Everything is
>> allright, except for after a reboot, there's no IPv6, while IPv4
>> works.  The router's ARP(6) table is empty, the machine doesn't answer
>> ping6.  However, if I start tcpdump -i bond0 ip6, everything is
>> allright again.  There are some indications that after some period
>> without IPv6 traffic, the same can happen again.  Are there known
>> issues which can exhibit themselves like this?  Other very similar
>> setups don't show this erratic behaviour.
>>
>> I know that the above doesn't give a fully detailed picture, but
>> thought that I'd better ask before taking the setup into pieces.
>
> This sounds to me like the same problem that I was having with
> OSPF, I think ARP(6) uses multicast ethernet address too. Can you try
> if the patch below, that I sent Patrick McHardy some days ago, fixes
> your problem?

Hi Jorge,

Thank you very much!  Your patch indeed fixes my problem.  I hope the
fix will make it into a stable release soon!
-- 
Regards,
Feri.