Re: problem statement [was Re: New Version Notification for draft-hinden-ipv4flag-00.txt]

Brian E Carpenter <> Sun, 19 November 2017 19:28 UTC

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Subject: Re: problem statement [was Re: New Version Notification for draft-hinden-ipv4flag-00.txt]
To: Nick Hilliard <>, Lorenzo Colitti <>
Cc: IETF IPv6 Mailing List <>
References: <> <> <> <> <> <>
From: Brian E Carpenter <>
Organization: University of Auckland
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Date: Mon, 20 Nov 2017 08:28:49 +1300
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On 20/11/2017 03:25, Nick Hilliard wrote:
> Lorenzo Colitti wrote:
>> Let's not forget about battery life. According to the numbers in RFC
>> 7772, on a phone even just sending DHCPv4 packets every 2 minutes could
>> reduce battery life by ~8% compared to a completely idle device.
> is there any guarantee in this situation that any other apps would not
> be chattering in the background over ipv6 anyway?  From what I've seen
> on tcpdump, mobile phones tend to be extraordinarily noisy, and a dhcpv4
> packet every two minutes would, in any situation where I've examined
> mobile phone traffic from normal handsets, be nothing more than
> background noise.
> Also, the whole internet isn't a mobile phone network, and what might be
> relevant or appropriate on a cell network might not be in any way
> relevant to another type of network.  

My phone has been instructed to prefer WiFi when there is a choice.

> Without meaning to state the
> obvious, it would be important to take this into account when framing
> any problem statement.
> One relatively straightforward way of dealing with extraneous dhcpv4
> packets would be to create a new dhcpv4 reply option hinting to the
> requester to cease DHCPv4 requests on the interface in question, or to
> slow down the request rate from one every two minutes to one every X
> minutes where X is network defined.

The hypothesis of this draft is that there is no IPv4 support, hence
nobody to send a DHCP(v4) reply.

otoh, unable to resist solutionism even in this thread, a minor update
to RFC2131 would allow battery-powered devices to slow down the
DHCPDISCOVER rate as much as they want to.