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Date:      Sun, 15 Apr 2018 16:30:45 -0400
From:      Nick Wolff <darkfiberiru@gmail.com>
To:        freebsd-net@freebsd.org
Subject:   QOS/TOS in carp/freebsd in general
Message-ID:  <CACxAneCODxbgA3qWDqtt%2B_dOZfEmUrCnw_T8eEovZK8a6c5GtQ@mail.gmail.com>

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 Hi,

I currently have a review in to make carp use dscp values on outgoing
packets. This will make it easier to preform QOS on modern switches as we
have been able to drive carp insane on 10g links while throwing storage
traffic at it.On an interesting side note apparently after 64k mac address
moves for a single mac address in the cam table arista 7050t  seems to with
out warning give up and stop moving address but leaves it in the table
where ever it last was.

I was originally going to just toggle between cs7 and the old TOS low delay
setting. But it was requested that I just make it a settable Integer value.
In this case I'm planning to do 0-63 to match dscp with a default of 54
(CS7) (Network Control) but you could still set the old value by setting
the sysctl to 4. Anything larger then 64 would be truncated as two shifts
are needed to align with the field leading.

Does anybody do anything anywhere with the old TOS values like low delay in
there networking infrastructure? Should this be updated in other places in
kernel and userland? It's been 20 years since TOS was deprecated and
replaced with DSCP.

Any other comments or thought are always welcome.

References:

Open Review - https://reviews.freebsd.org/D14536
General DSCP reference - https://www.tucny.com/Home/dscp-tos


Thanks,

Nick "darkfiberiru" Wolff



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