netdev - Re: [PATCH] vlan: Make it possible to add vlan with id 4095

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Date:	Mon, 12 Nov 2012 11:01:21 -0800
From:	Ben Greear <greearb@...delatech.com>
To:	Jan Engelhardt <jengelh@...i.de>
CC:	David Miller <davem@...emloft.net>, paulius.zaleckas@...il.com,
	kaber@...sh.net, netdev@...r.kernel.org
Subject: Re: [PATCH] vlan: Make it possible to add vlan with id 4095

On 11/12/2012 10:42 AM, Jan Engelhardt wrote:
> On Friday 2012-09-28 19:44, David Miller wrote:
>
>> From: Paulius Zaleckas <paulius.zaleckas@...il.com>
>> Date: Fri, 28 Sep 2012 15:32:58 +0300
>>
>>> vconfig help tells that vlan_id should be 0-4095, but fails
>>> with 4095.
>>>
>>> There is an off-by-one bug while evaluating vlan_id.
>>> Fix it by evaluating against count(4096), not mask(0x0fff = 4095).
>>>
>>> Signed-off-by: Paulius Zaleckas <paulius.zaleckas@...il.com>
>>
>> Awesome, we don't need VXVLAN any more after this fix.
>
> You mean because the special 0xfff value could indicate "here's more
> headers"? Sounds like a plan.

You can't just use reserved values...they are for the standards writers
in case they ever need to officially extend the 802.1q spec somehow.

If you use it for non-standard purposes, you can set up conflicts with
future standards.

Thanks,
Ben

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

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