From: Krzysztof Halasa <khc@pm.waw.pl>
To: Ben Greear <greearb@candelatech.com>
Cc: andrei radulescu-banu <iubica2@yahoo.com>,
Stephen Hemminger <shemminger@linux-foundation.org>,
Patrick McHardy <kaber@trash.net>,
linux-kernel@vger.kernel.org,
Linux Netdev List <netdev@vger.kernel.org>
Subject: Re: Linux, tcpdump and vlan
Date: Sat, 21 Jul 2007 23:15:43 +0200 [thread overview]
Message-ID: <m3ps2l5ugw.fsf@maximus.localdomain> (raw)
In-Reply-To: <46A248FA.1050403@candelatech.com> (Ben Greear's message of "Sat, 21 Jul 2007 10:57:14 -0700")
Ben Greear <greearb@candelatech.com> writes:
>> IOW: I think all Ethernet interfaces should always be VLAN-aware,
>> stripping the tag (only one) early on RX and adding it late on TX.
>> That means tcpdump would see packets with exactly one tag removed
>> (unless there was no tag), in both RX and TX.
>>
>> Tcpdump would need other means to get VLAN id...
>>
> What benefit will this add? It will certainly decrease performance to
> copy around
> the header for every VLAN packet, so there would have to be a good reason to
> add this logic...
I'd have to do some tests... Hopefully in this decade, forget it for
now.
The primary reason - consistency with hw VLAN cards -> simpler
code.
The performance is already decreased (not sure if it's noticeable)
most of the time, i.e., when not transparently bridging VLAN
trunks. Bridging VLAN trunks is, of course, theoretically possible,
but it's rather not a common operation when using .1Q.
That is, with header reordering, of course.
Anyway, -ENOPATCH from me for now.
--
Krzysztof Halasa
next prev parent reply other threads:[~2007-07-21 21:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-19 16:02 Linux, tcpdump and vlan 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 [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-07-19 21:38 andrei radulescu-banu
2007-07-19 23:38 ` Ben Greear
2007-07-20 20:19 ` Krzysztof Halasa
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 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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