Re: [v6ops] new draft: draft-yc-v6ops-solicited-ra-unicast

Andrew Yourtchenko <> Fri, 17 July 2015 16:57 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id ED64E1AC3D6 for <>; Fri, 17 Jul 2015 09:57:40 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2
X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, SPF_PASS=-0.001] autolearn=ham
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id zLktWUKn_qIy for <>; Fri, 17 Jul 2015 09:57:39 -0700 (PDT)
Received: from ( [IPv6:2a00:1450:400c:c05::22a]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 41CF41ABD3F for <>; Fri, 17 Jul 2015 09:57:39 -0700 (PDT)
Received: by wibud3 with SMTP id ud3so43838985wib.1 for <>; Fri, 17 Jul 2015 09:57:38 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20120113; h=content-type:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=pyQuxi7PHUtES/S1BjjKCeIRky6MyHExb+56fsCe5Y8=; b=OJ2zwxtxQFrAIIXctky67KktNJzeQgR8iPIlFcxBs21Ef30mL3yhW/6Ua8QLA4l7wg Kj9Up9Bi6Y53VEwtSLtdaqcr5HwBHWTxaL0L7XygLUw+T/fCozUDdCVpMw9YlylxkzXn PES5F6xq7XgfntX4SFc/budme9h0s+nTmnYu2rlxZiPCEhRW5ceszMYvT9w/n8AfdydR 1MNTxJ9SJUROganS5TVG38o9ZwJeYkaU7i7ibJuGpcVZWxE5wB4FvQR1eYFxdXgXTLCc 5FeIAC8A9Vj2qH8DtdyfVjiIDaPN9sgu+8MVAyVtm6l1KtCN+zOA757NudoztnSi6h5g tHIg==
X-Received: by with SMTP id my10mr18532264wic.41.1437152258012; Fri, 17 Jul 2015 09:57:38 -0700 (PDT)
Received: from [] ([]) by with ESMTPSA id fo17sm19115420wjc.46.2015. (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 17 Jul 2015 09:57:36 -0700 (PDT)
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (1.0)
From: Andrew Yourtchenko <>
X-Mailer: iPhone Mail (12H143)
In-Reply-To: <>
Date: Fri, 17 Jul 2015 18:57:32 +0200
Content-Transfer-Encoding: quoted-printable
Message-Id: <>
References: <> <> <> <> <> <> <> <>
To: "Fred Baker (fred)" <>
Archived-At: <>
Cc: "" <>, v6ops list <>
Subject: Re: [v6ops] new draft: draft-yc-v6ops-solicited-ra-unicast
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: v6ops discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Fri, 17 Jul 2015 16:57:41 -0000

On 17 Jul 2015, at 09:34, Fred Baker (fred) <> wrote:

>> So the next logical thing to do would be to have the router default to
>> unicast Router Advertisements, measure the rate of received Router
>> Solicitations, and switch to multicast RA mode past a certain
>> threshold to cover this sort of situation. Once the number of RSes
>> falls, it switches back to unicast RA mode.
>> That would get rid of the configuration knob proposed in this ID, and
>> is behaviour that I think could be universal for all link types,
>> rather than just for the case of wireless ones with mobile devices.
> If it were me implementing it, I think I would go about this in a little different way, hopefully simpler. I would want to send at most one (e.g., either zero or one) RA per some interval (a second?). In the normal case, that is sent unicast. However, having sent a unicast RA at time t, if I now receive another RS before t+1, I send the next one (at time t+1) as a multicast.

values of T less than 3 seconds would make performance worse than today.

There are many things to optimize for:

- wireless airtime
- bandwidth used by RAs
- CPU usage sending unicast RAs by router
- energy consumption on devices for more than one medium

Some of them are orthogonal, some of them contradict each other, some of them align. People may want to optimize differently.

I'd opt for simplicity - and use the text Erik Kline posted in another email.

This would allow the developers to adapt for individual use cases on the spot.


> _______________________________________________
> v6ops mailing list