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Date: Mon, 30 Mar 2015 14:59:16 +0200
From: Hans Petter Selasky <hps@selasky.org>
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To: Gleb Smirnoff <glebius@FreeBSD.org>
Subject: Re: svn commit: r280759 - head/sys/netinet
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Cc: Adrian Chadd <adrian@freebsd.org>,
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On 03/30/15 14:51, Gleb Smirnoff wrote:
>    Hans,
>

Gleb: Can you answer my question first:

Should the 16-bit IP ID field carry any useful information or not?

> On Mon, Mar 30, 2015 at 02:38:12PM +0200, Hans Petter Selasky wrote:
> H> > DELAY() into network stack? Are you serious now or kidding me?
> H>
> H> If there should be any useful meaning in the 16-bit IP ID field, the
> H> value can't be allowed to wrap several times in a millisecond. Given the
> H> context from where the network code is running, msleep() is not an
> H> option. A _conditional_ DELAY() of 1-2 us, is maybe all we need to
> H> prevent the value from wrapping too quickly. It is not perfect and it is
> H> indeed consuming more CPU.
>
> Let me ask again: are you serious? Do you suggest to delay transmitting
> network packets with a DELAY()?
>
> H> Or maybe we can add an IPv4 option to escape a 32-bit IP ID field and
> H> don't use the 16-bit IP ID field.
>
> Is that also serious? Do you suggest to change layout of IP packet?
>

--HPS