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From: Ben Greear <greearb@candelatech.com>
To: Andy Gospodarek <andy@greyhouse.net>
Cc: bridge@osdl.org, Benny Amorsen <benny+usenet@amorsen.dk>
Subject: Re: [Bridge] Re: Small packets
Date: Mon, 29 Oct 2007 08:48:54 -0700	[thread overview]
Message-ID: <472600E6.7060203@candelatech.com> (raw)
In-Reply-To: <bdfc5d6e0710290806o81321bbhcaaa7d936a50bb0c@mail.gmail.com>

Andy Gospodarek wrote:
> On 10/29/07, Benny Amorsen <benny+usenet@amorsen.dk> wrote:
>>>>>>> "LS" == Leigh Sharpe <lsharpe@pacificwireless.com.au> writes:
>> LS> Standard e1000 hardware. The packets being bridged contain a VLAN
>> LS> tag, which is included in the 60 bytes.
>>
>> The e1000 has VLAN acceleration. The VLAN tag is sent in a separate
>> register. If you do packet capture on the sender, the packet will
>> likely look 60 bytes long, even if it is 64 bytes on the wire.
>>
>> The same thing happens on receive. Packet dumping with VLAN's is a bit
>> of a mess in Linux. If you're lucky you can find a card without VLAN
>> acceleration to do the packet dump.
>>
>>
>> /Benny
>>
> 
> Are these the lengths on the wire or when captured on the host?   The
> smallest VLAN tagged frame should be 68 bytes IIRC.  A tagged frame
> that is 64 bytes seems too small.

That is not correct per the 802.1Q VLAN RFC, though
I don't have the reference handy at the moment.

64 bytes is fine, vlan tagged or otherwise.


Thanks,
Ben



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-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com


  reply	other threads:[~2007-10-29 15:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-29  5:40 [Bridge] Small packets Leigh Sharpe
2007-10-29 13:06 ` [Bridge] " Benny Amorsen
2007-10-29 15:06   ` Andy Gospodarek
2007-10-29 15:48     ` Ben Greear [this message]
2007-10-29 16:15       ` Andy Gospodarek

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