From: Ben Greear <greearb@candelatech.com>
To: andrei radulescu-banu <iubica2@yahoo.com>
Cc: Patrick McHardy <kaber@trash.net>,
Stephen Hemminger <shemminger@linux-foundation.org>,
Krzysztof Halasa <khc@pm.waw.pl>,
linux-kernel@vger.kernel.org,
Linux Netdev List <netdev@vger.kernel.org>
Subject: Re: Linux, tcpdump and vlan
Date: Thu, 19 Jul 2007 16:38:57 -0700 [thread overview]
Message-ID: <469FF611.6080905@candelatech.com> (raw)
In-Reply-To: <930446.33248.qm@web56601.mail.re3.yahoo.com>
andrei radulescu-banu wrote:
> During debugging, I noticed that dev_queue_xmit() is called twice for tx vlan frames. This results in a frame being passed twice to a packet socket bound to 'any' interface. If the packet socket is bound to a specific interface, though, it will get only one copy of the tx frame, which is good.
>
> In more detail: suppose we're tx'ing a frame, and the route table lookup yields a vlan outgoing device eth0.2. dev_queue_xmit() is called, which calls dev_queue_xmit_nit() for dev = eth0.2 then dev->hard_start_xmit() for dev = eth0.2.
>
> The latter call gets into the vlan layer, which attaches the vlan id 2 (accelerated or not... in my e1000 case accelerated) then calls dev_queue_xmit() again. This time around dev_queue_xmit_nit() is called for dev = eth0, and dev->hard_start_xmit() actually calls the ethernet driver.
>
> The net result is that dev_queue_xmit_nit() is called twice, once for dev=eth0.2 then for dev=eth0.
Maybe binding to all isn't such a good idea then.
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2007-07-19 23:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-19 21:38 Linux, tcpdump and vlan andrei radulescu-banu
2007-07-19 23:38 ` Ben Greear [this message]
2007-07-20 20:19 ` Krzysztof Halasa
-- strict thread matches above, loose matches on Subject: below --
2007-07-19 18:20 andrei radulescu-banu
2007-07-19 19:28 ` Stephen Hemminger
2007-07-19 17:46 andrei radulescu-banu
2007-07-19 16:02 andrei radulescu-banu
2007-07-20 19:58 ` Krzysztof Halasa
2007-07-20 20:34 ` Ben Greear
2007-07-21 11:32 ` Krzysztof Halasa
2007-07-21 17:57 ` Ben Greear
2007-07-21 21:15 ` Krzysztof Halasa
2007-07-19 15:47 andrei radulescu-banu
2007-07-19 16:21 ` Stephen Hemminger
2007-07-19 16:33 ` Patrick McHardy
2007-07-19 16:47 ` Ben Greear
[not found] <878246.51044.qm@web56608.mail.re3.yahoo.com>
2007-07-18 22:57 ` Patrick McHardy
2007-07-18 23:22 ` Ben Greear
2007-07-18 23:34 ` Patrick McHardy
2007-07-19 0:01 ` Ben Greear
2007-07-19 0:19 ` Patrick McHardy
2007-07-19 13:28 ` Krzysztof Halasa
2007-07-19 13:41 ` Stephen Hemminger
2007-07-19 14:00 ` Patrick McHardy
2007-07-19 14:23 ` Krzysztof Halasa
2007-07-19 15:00 ` Stephen Hemminger
2007-07-19 15:45 ` Krzysztof Halasa
2007-07-19 15:20 ` Stephen Hemminger
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