From: Ben Greear <greearb@candelatech•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: netdev <netdev@vger•kernel.org>
Subject: Re: IPv4 multicast and mac-vlans acting weird on 3.0.4+
Date: Wed, 05 Oct 2011 13:19:34 -0700 [thread overview]
Message-ID: <4E8CBBD6.3080500@candelatech.com> (raw)
In-Reply-To: <1317845835.3457.5.camel@edumazet-laptop>
On 10/05/2011 01:17 PM, Eric Dumazet wrote:
> Le mercredi 05 octobre 2011 à 13:09 -0700, Ben Greear a écrit :
>> On 10/05/2011 12:54 PM, Eric Dumazet wrote:
>>> Le mercredi 05 octobre 2011 à 09:46 -0700, Ben Greear a écrit :
>>>> This is on a hacked 3.0.4 kernel...
>>>>
>>>> I am seeing an issue where an IPv4 mcast receiver will not receive
>>>> a 1473 or larger byte mcast message, but will receive a 1472. The difference
>>>> being that 1473 ends up being two packets on the wire. It works on
>>>> 802.1Q VLANs, VETH interfaces and real Ethernet. It does not work
>>>> on a mac-vlan hanging off the VETH.
>>>>
>>>> I see packets received on the macvlan in tshark, and they appear correct. No
>>>> obvious errors in the macvlan port stats or netstat -s,
>>>> and the 'ss' tool doesn't appear to support UDP sockets at all.
>>>>
>>>> So, I'm about to go digging into the code, but if anyone has any
>>>> suggestions for places to look, please let me know!
>>>>
>>>
>>> Well, problem is defragmentation and macvlan cooperation.
>>>
>>> Multicast messages are broadcasted on all macvlan ports.
>>>
>>> But IP defrag will probably deliver a single final frame.
>>>
>>> We probably need to handle defrag in macvlan before broadcasting to all
>>> ports.
>>
>> I see packets get to this code in ip_input.c (line 467 or so),
>> and that printk is mine of course.
>>
>> if ((dev&& strcmp(dev->name, "rddVR10#0") == 0) ||
>> (dev&& strcmp(dev->name, "rddVR10") == 0)) {
>> printk("calling ip_rcv_finish through NF_HOOK, dev: %s, len: %i\n",
>> dev->name, skb->len);
>> }
>>
>> return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
>> ip_rcv_finish);
>>
>> But, the macvlan packets never make it to the ip_rcv_finish method.
>>
>> I do see a big and a little packet entering this code.
>>
>> I have no firewall rules that I'm aware of, though there
>> is some conn-track logic (though not associated with the
>> mac-vlan interface):
>
> Say you have 10 vlans on your eth0, how many times do you want one
> incoming multicast frame being delivered to your application listening
> on 0.0.0.0:port ?
How would it work for two Ethernet devices on the same LAN? I'd
say that mac-vlans should mimic that case.
And in my case, I'm binding hard to a device & IP address,
so my app should get it once regardless.
Thanks,
Ben
--
Ben Greear <greearb@candelatech•com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2011-10-05 20:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-05 16:46 IPv4 multicast and mac-vlans acting weird on 3.0.4+ Ben Greear
2011-10-05 19:54 ` Eric Dumazet
2011-10-05 20:09 ` Ben Greear
2011-10-05 20:17 ` Eric Dumazet
2011-10-05 20:19 ` Ben Greear [this message]
2011-10-05 20:31 ` Eric Dumazet
2011-10-05 20:56 ` Ben Greear
2011-10-05 21:36 ` Eric Dumazet
2011-10-05 21:52 ` Ben Greear
2011-10-05 22:35 ` Ben Greear
2011-10-06 20:28 ` [PATCH net-next] macvlan: handle fragmented multicast frames Eric Dumazet
2011-10-07 16:44 ` Ben Greear
2011-10-10 16:27 ` Ben Greear
2011-10-10 16:41 ` Eric Dumazet
2011-10-10 16:53 ` Ben Greear
2011-10-19 3:22 ` David Miller
2011-10-06 20:42 ` IPv4 multicast and mac-vlans acting weird on 3.0.4+ Eric Dumazet
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