netdev - Re: [net-next PATCH 0/2] GENEVE/VXLAN: Enable outer Tx checksum by default

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Date:	Tue, 23 Feb 2016 10:32:32 -0800
From:	Tom Herbert <tom@...bertland.com>
To:	David Miller <davem@...emloft.net>
Cc:	Jesse Gross <jesse@...nel.org>, Edward Cree <ecree@...arflare.com>,
	Alex Duyck <aduyck@...antis.com>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Alexander Duyck <alexander.duyck@...il.com>
Subject: Re: [net-next PATCH 0/2] GENEVE/VXLAN: Enable outer Tx checksum by default

On Tue, Feb 23, 2016 at 10:26 AM, David Miller <davem@...emloft.net> wrote:
> From: Tom Herbert <tom@...bertland.com>
> Date: Tue, 23 Feb 2016 09:42:00 -0800
>
>> Why not just fix the stack to conform to RFC6864? As Edward pointed
>> out we lose the actual IP ID's in GRO anyway, so attempts to set them
>> in GSO may be wildly incorrect from the source point of view-- even in
>> that case were probably better off changing the IP identifier to zero
>> (okay since we're already breaking the E2E model anyway :-) ).
>
> Tom, you can't, you'll break TCP header compression schemes which
> expect a monotonically increasing IP ID value.
>
> We tried setting the IP ID to zero for frames with DF set, it broke
> things.

All the more reason to move to IPv6 ;-)