Subject: [v6ops] IPv6-only wifi during IETF meetings? - expect higher energy consumption

From: Alexandre Petrescu <[email-masked]>
Date: Wed, 16 Nov 2016 19:21:23 +0900

Hi,

During today's Plenary there was discussion about making IPv6 only wifi 
during some IETF meeting.

If so, I was wondering whether people will perceive a larger battery 
drain in their devices?

I am asking because we performed some measurements on a recent 
smartphone comparing various Internet usage (youtube, real-time, web 
browsing, ftp, etc.) and we seemed to find that IPv6 draws around 5% 
more energy from the battery than IPv4.  That was on cellular, maybe 
wifi is different...

Alex

---

From: "Heatley, Nick" <[email-masked]>
Date: Wed, 16 Nov 2016 10:38:17 +0000

Can you be more specific on the test conditions?
Key question, was the phone dual stack or IPv6-only?
Was the tcp performance identical (but battery drain different)?
I would struggle to get accuracy to less than 15%, without keeping within a perfect lab environment.

From: v6ops [mailto:[email-masked]] On Behalf Of Alexandre Petrescu
Sent: 16 November 2016 10:21
To: [email-masked]
Subject: [v6ops] IPv6-only wifi during IETF meetings? - expect higher energy consumption

Hi,

During today's Plenary there was discussion about making IPv6 only wifi during some IETF meeting.

If so, I was wondering whether people will perceive a larger battery drain in their devices?

I am asking because we performed some measurements on a recent smartphone comparing various Internet usage (youtube, real-time, web browsing, ftp, etc.) and we seemed to find that IPv6 draws around 5% more energy from the battery than IPv4.  That was on cellular, maybe wifi is different...

Alex

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---

From: Jen Linkova <[email-masked]>
Date: Wed, 16 Nov 2016 14:42:56 +0100

> If so, I was wondering whether people will perceive a larger battery drain

Why? The current 'default' SSID (ietf) is dual-stack.
If you switch to v6-only SSID, then you get rid of IPv4 and, as a
result, ARP noise etc.

> I am asking because we performed some measurements on a recent smartphone
> comparing various Internet usage (youtube, real-time, web browsing, ftp,
> etc.) and we seemed to find that IPv6 draws around 5% more energy from the
> battery than IPv4.  That was on cellular, maybe wifi is different...

So you compared v4-only connectivity to v6-only? Or dual-stack to v6-only?

Anyway you can always try yourself - use 'ietf' ssid for one day and
ietf-nat64 for another ;)

My phone has been connected to ietf-nat64 the whole week, I have not
noticed any battery issues so far.

-- 
SY, Jen Linkova aka Furry

---

From: Alexandre Petrescu <[email-masked]>
Date: Thu, 17 Nov 2016 10:40:50 +0900

Le 16/11/2016 à 22:42, Jen Linkova a écrit :
> Why? The current 'default' SSID (ietf) is dual-stack. If you switch
> to v6-only SSID, then you get rid of IPv4 and, as a result, ARP noise
> etc.

Jen, I can understand the v6-only SSID at IETF will not have any ARP on
it.  But it would have some ND instead, right?

>> smartphone comparing various Internet usage (youtube, real-time,
>> web browsing, ftp, etc.) and we seemed to find that IPv6 draws
>> around 5% more energy from the battery than IPv4.  That was on
>> cellular, maybe wifi is different...
>

I do not know what you mean by 'dual-stack'?  There were two stacks in
this smartphone: an IPv4 stack and an IPv6 stack.  The wireshark dumps
show only IPv4 traffic when testing IPv4 and only IPv6-traffic when
testing IPv6.

The smartphone is connected to an IPv6-only cellular APN when testing
IPv6 and to an IPv4-only APN when testing IPv4.

I suppose this is the right way to test IPv4 vs IPv6.

> ietf-nat64 for another ;)

I have a big problem with both 'ietf' and 'ietf-nat64' SSIDs at IETF
since multiple IETF meetings now.

My recent Windows laptop does not want to connect to any of these two -
it complains about some certificate matters.

For this reason I only use ietf-legacy while at IETF.

(and yes I asked both IETF network operators and my IT - they blame each
other)

> noticed any battery issues so far.

Well yes, I can understand that.  But I am not expecting spectacular
things like 50% more battery drain.

The measured approx 5% more power consumption could be noticed in some
extreme situation.  One would have to bring that smartphone close to the
battery exhaustion limit, and be in a place without recharge
possibility.  In this situation a user would turn off WiFi, GPS,
inertial sensor, dim the screen, stop some apps, and... prefer IPv4.

Alex

---

From: Alexandre Petrescu <[email-masked]>
Date: Thu, 17 Nov 2016 10:41:04 +0900

> Key question, was the phone dual stack or IPv6-only?

I will reply with what I know, but I dont know what you mean by 'dual
stack'?

The tests were performed with an of-the-shelf Android phone on the
market this year.  This OS has two stacks inside: an IPv4 stack and an
IPv6 stack.  But I am afraid you could mean something else by 'dual stack'.

When we tested the IPv6 stack the smartphone was connected on an
IPv6-only APN ("APN" is somehow the cellular equivalent of an ESSID in
WiFi).

When we tested the IPv4 stack the smartphone was connected on an
IPv4-only APN.

We will have to add this clarification.

It's true I could not find an /etc/resolv.conf file, even though the DNS
resolution worked fine; I suppose this has something to do with you
talking about dual-stack.  Or maybe not.

> Was the tcp performance identical (but battery drain different)?

We did not focus on measuring the TCP performance in particular.  Not
sure what kind of test of TCP performance would one expect?  (something
like running iperf?  something like measuring useful packet reception vs
retransmission rates? something like looking at an advancement bar feel
how fast it advances?)

> within a perfect lab environment.

I agree, accuracy varies a lot, many measurements are performed and
means can be expressed (averages, medians, deviations, etc.).

Alex

>
>
> *From:*v6ops [mailto:[email-masked]] *On Behalf Of *Alexandre
> Petrescu *Sent:* 16 November 2016 10:21 *To:* [email-masked]
> *Subject:* [v6ops] IPv6-only wifi during IETF meetings? - expect
> higher energy consumption
>
>
>
> Hi,
>
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---

From: Jen Linkova <[email-masked]>
Date: Thu, 17 Nov 2016 04:43:20 +0100

> it.  But it would have some ND instead, right?

Not instead. ND is already here on the default ("IETF") SSID.
So those people who are on the default SSID and are seeing ND + ARP currently,
will see just ND if/when the default SSID becomes IPv6-only.

> IPv6 and to an IPv4-only APN when testing IPv4.

That was my question, what did you compare a phone on v6-only APN'
with: a phone connected to v4-only or dual-stack APN?
Anyway I could not comment on your 5% results w/o knowing more on your
testing/measuring methodology...

> For this reason I only use ietf-legacy while at IETF.

Does your phone has the same problem?

> inertial sensor, dim the screen, stop some apps, and... prefer IPv4.

If you turn off WiFi - it does not matter what version of protocol you
prefer on the disabled interface ;))

---

From: Alexandre Petrescu <[email-masked]>
Date: Thu, 17 Nov 2016 14:19:07 +0900

> will see just ND if/when the default SSID becomes IPv6-only.

Ah I see.  So it may be that currently the computers on SSID see too 
much traffic (both ND and ARP) and may draw them more battery than if 
they only saw one.

> with: a phone connected to v4-only or dual-stack APN?

Yes.

> testing/measuring methodology...

I agree, I will have to put the numbers and the testing conditions in a 
draft.

> Does your phone has the same problem?

This is something to try.  I dont know.

There may be some differences between how much the company laptop is 
tuned by the IT department, and the smartphone.  Is your smartphone 
tuned by your IT department?

> prefer on the disabled interface ;))

I meant one could still use the cellular interface.

It's true that on some smartphones the cell iface consumes more than the 
wifi, or vice-versa.  But there's always advantage in turning off one of 
them if needing to save battery.

Alex

---

From: Jen Linkova <[email-masked]>
Date: Thu, 17 Nov 2016 08:14:43 +0100

On Thu, Nov 17, 2016 at 6:19 AM, Alexandre Petrescu
<[email-masked]> wrote:
>> ND is already here on the default ("IETF") SSID.
> Ah I see.  So it may be that currently the computers on SSID see too much
> traffic (both ND and ARP) and may draw them more battery than if they only
> saw one.

Exactly.
Oh, have we just concluded that running v6-only might improve users
experience? ;)

> I agree, I will have to put the numbers and the testing conditions in a

Well, if we assume that
1) battery usage is linearly proportional to  bytes transmitted
2) average packet size is ~500 bytes
(disclaimer: both statements might be found questionable),
then, as for each packet v6 would add 20 more bytes (20 bytes v4
header vs 40 bytes v6 header), those 20 bytes would give
those 5% of 500 bytes...(credits for such calculations go to a
colleague of mine who is not on this list ;)

---

From: Nabil BENAMAR <[email-masked]>
Date: Thu, 17 Nov 2016 10:39:23 +0000

Hi Alex,

Best Regards,
Nabil 

> On Nov 17, 2016, at 1:40 AM, Alexandre Petrescu <[email-masked]> wrote:
> 
> 
> 

Obviously….ARP is not used anymore in IPv6 networks! ND is part of IPv6 processes (RA,RS, NA, NS, etc…)
> show only IPv4 traffic when testing IPv4 and only IPv6-traffic when

Dual-stack means that you have both IPv4 and IPv6 addresses for your wifi interface. I think that your setup is the most correct one, because it will test ipv6 only vs ipv4 only. In dual-stack environment, the results will be different and related to the application measured: happy-eyeballs implemented or not, etc….
>> ietf-nat64 for another ;)

I do not think that ietf-nat64 will be convenient for this study !
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