netdev - Re: [PATCH v2 net-next] net: ipv4: Add ability to have GRE ignore DF bit in IPv4 payloads

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Date:	Wed, 15 Jun 2016 21:40:23 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	philipp@...fish-solutions.com
Cc:	netdev@...r.kernel.org, stephen@...workplumber.org,
	alexander.duyck@...il.com
Subject: Re: [PATCH v2 net-next] net: ipv4: Add ability to have GRE ignore
 DF bit in IPv4 payloads

From: "Philip Prindeville" <philipp@...fish-solutions.com>
Date: Tue, 14 Jun 2016 15:53:02 -0600

> From: Philip Prindeville <philipp@...fish-solutions.com>
> 
>     In the presence of firewalls which improperly block ICMP Unreachable
>     (including Fragmentation Required) messages, Path MTU Discovery is
>     prevented from working.
>     
>     A workaround is to handle IPv4 payloads opaquely, ignoring the DF bit--as
>     is done for other payloads like AppleTalk--and doing transparent
>     fragmentation and reassembly.
>     
>     Redux includes the enforcement of mutual exclusion between this feature
>     and Path MTU Discovery as suggested by Alexander Duyck.
>     
>     Cc: Alexander Duyck <alexander.duyck@...il.com>
>     Reviewed-by: Stephen Hemminger <stephen@...workplumber.org>
>     Signed-off-by: Philip Prindeville <philipp@...fish-solutions.com>

Applied.