netdev - Re: [PATCH v2] net: ip/tnl: Set iph->id only when don't fragment is not set

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Message-ID: <10e81a17-6b38-3cfa-8bd2-04ff43a30541@gmail.com>
Date:   Tue, 26 Nov 2019 14:45:48 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Oliver Herms <oliver.peter.herms@...il.com>,
        David Miller <davem@...emloft.net>
Cc:     yoshfuji@...ux-ipv6.org, kuznet@....inr.ac.ru,
        netdev@...r.kernel.org
Subject: Re: [PATCH v2] net: ip/tnl: Set iph->id only when don't fragment is
 not set



On 11/26/19 11:10 AM, Oliver Herms wrote:
> 
> What do you think about making this configurable via sysctl and make the current
> behavior the default? I would also like to make this configurable for other 
> payload types like TCP and UDP. IMHO there the ID is unnecessary, too, when DF is set.
>

Certainly not.

I advise you to look at GRO layer (at various stages, depending on linux version)

You can not 'optimize [1]' the sender and break receivers ( including old ones )

[1] Look at ip_select_ident_segs() : the per-socket id generator makes
ID generation quite low cost, there is no real issue here.