netdev - Re: ARP response with link local IP, why not broadcast

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Message-ID: <CACP96tRrCzFwTC-fSMxGTWr+zFSkid=Bd6JkGZA822HbEjk4_Q@mail.gmail.com>
Date:	Tue, 21 Jul 2015 21:39:06 +0200
From:	Sowmini Varadhan <sowmini05@...il.com>
To:	Sebastian Fett <db_extern@....de>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: ARP response with link local IP, why not broadcast

On Tue, Jul 21, 2015 at 4:38 PM, Sebastian Fett <db_extern@....de> wrote:
> Hello!
>
> According to RFC3927 every ARP packet (reply and request) should be sent as
> link layer broadcast as long as the sender IP is a link local address. (see
> chapter 2.5).

Because broadcast replies are noisy and should be avoided.
if possible- it creates a broadcast flood that would wake up all receivers,
and is especially undesirable in today's world, where bcast would wake
up sleepy devices, or require other inefficient processes in a cloud env.
See also https://www.ietf.org/id/draft-nordmark-6man-dad-approaches-01.txt

> That functionality would help me a lot with a use case I have with our
> application.

what is your use case?

>
> But it is not implemented in the kernel that way.
> Does anyone know why?

--Sowmini
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