Re: [recipe] FYI: [admin-discuss] REMINDER: IETF carbon emission measurement workshops on 20 and 21 September

[Hesham ElBakoury <[e-mail]>]

I agree that that FCT is the right metric for congestion control. Please
refer to Nandita and Nick McKeown 2006 paper
https://people.eecs.berkeley.edu/~sylvia/cs268-2019/papers/rcp-ccr.pdf

They proposed RCP (Rate Control Protocol) which minimizes FCT. But I am not
sure if RCP is deployed in operator networks.

Minimizing FCT can help reduce energy consumption by maximizing the sleep
time of network resources such as routers/switches or their interfaces. The
problem is that the activation cost of turning on these resources from a
sleep state can be very expensive and time consuming which may disrupt
running services. How we can achieve the best balance between FCT and
energy consumption without impacting running services?

In general there are papers in the literature which study the adaptive
network topology problem where network resources are put to sleep to reduce
energy consumption. I do not think any of these papers have solutions that
operators can deploy in their network. Moreover, operators may not trust
software to put network resources to sleep specially in critical parts of
their networks.

It is worth noting that there are papers which look into using optimization
techniques (e.g.dynamic programming) in the data center to provide balance
between energy consumption and FCT. Here is a recent one
https://arxiv.org/pdf/2206.01360

What IETF can do to address these issues?

Thanks
Hesham

On Sat, Sep 24, 2022, 7:43 AM Michael Welzl <[e-mail]> wrote:

> Hi !
>
> I’m answering to both Toerless and Cedric in one email here.
>
> Toerless:
>
> On Sep 22, 2022, at 8:08 PM, Toerless Eckert <[e-mail]> wrote:
>
> Michael:
>
> There where unfortunately only very few folks attending the IETF LLC admin
> meeting here
> the current IETF plan to simply start to estimate the IETF meetings
> CO2/greenhouse-emissions
> was presented. But it did look like a good first small step on a long road.
>
> For something like IETF meetings the next logical step IMHO is to discuss
> if or how there
> is a benefit in some form of carbon offsetting. I think they've planned
> that as a next step.
> I'd certainly like to learn more about that option because all i've read
> so far about it
> is that most carbon offsetting seems to look fairly problematic to me. But
> maybe there are
> some good options.
>
>
> Sure, such things is a useful thing to discuss - but still, to me, it may
> only be a drop in the bucket compared to the potential that the IETF has
> when it comes to reducing energy for the Internet.
> Whether the Internet truly makes up half, 1/4, even 1/10 of the aviation
> industry’s GHG emissions… just imagine the potential impact if we manage to
> even only reduce its energy by a small amount, but at a global scale!
>
>
> On the admin-discuss mailing list there was also an interesting pointer to
> a european
> conference recommendations how to minimize carbon emissions for meetings.
> It looked
> pretty good except that it didn't put different options into perspective.
> E.g.: it said
> that reduccing video conference resolution from HD/4k to SD would reduce
> up to (forgot, e.g.:)
> 70% energy consumption. Which i think may be true that lets say some 5% of
> the total
> video stream network required energy might be changing based on
> resolution, even the whole
> 100% of the network/end-user energy requirements. Which in itself would
> likely be just a small
> portion of the energy of in-person meeting. In my
> draft-eckert-ietf-and-energy-overview,
> i cited https://www.sciencedirect.com/science/article/pii/
> S0140366414000620 which is a bit
> old by now (aka: energy consumption of video likely having gone down
> already due to lower energy
> per bit now), but still a good example of a comparative approach.
>
>
> I would be against trading quality of online meetings: as you say, this is
> a tiny portion of the energy of in-person meeting … so it’s probably more
> important to ensure the best possible online experience.
> I think we shouldn’t focus on trade-offs too much. There are ways to
> reduce energy that do not embed a trade-off, and in some cases it can even
> be a win-win (shorter FCT = more sleep time for devices).
>
> Cedric:
>
> On Sep 22, 2022, at 11:53 PM, Cedric Westphal <
> [e-mail]> wrote:
>
> HI Michael & Toerless:
>
> Michael: thank you very much for the data points.
>
> Regarding your paper: I really like the idea that protocols can help
> saving energies. When we wrote our draft
> https://datatracker.ietf.org/doc/draft-cx-green-ps/ we were a bit
> disappointed that the protocol side of things didn’t have great
> opportunities for reducing energy consumption – aside of course of
> facilitating sleep modes as you suggest in your paper. If you have a chance
> to read it, we would welcome your comments. I’m currently updating it for
> London.
>
>
> I did read the draft, but didn’t have any comments. I did find it
> interesting though!  I’ll be in London too, btw, and I’ll give a brief
> presentation on the relationship between energy saving and congestion
> control (just the simple result from my paper) to ICCRG there. I think
> there are plenty of opportunities in protocols - they just need to be
> worked out, evaluated, …   I mean, you point out some interesting
> opportunities in your own draft.
>
>
> Your paper seem to argue that short/high bandwidth transmissions are
> better than longer/slower ones – we wrote something like this in our paper
> https://scholar.google.com/citations?view_op=view_citation&citation_for_view=5WcgOxMAAAAJ:rJyh6hJnyfgC
>  (upon which the draft is based on) and we got some pushback to the
> extent that: short/fast = burstiness = high buffers = packet loss =
> re-transmissions.
>
>
> Thanks, i’ll read this.
> Regarding bursts, I think we shouldn’t think about “bursts” and even use a
> different word. Bulk? “Send data in bulk” as opposed to "sending a burst”?
>
> This is an important distinction because data in bulk can (and probably
> should) still be paced - we really shouldn’t be sending bursts if we can
> avoid them. What I mean is something like sending 100 paced packets in 1
> RTT instead of 10 packets per RTT over 10 RTTs.  In fact, the Internet does
> the latter kind of transmission often enough. Given typical flow lengths
> and growing capacities, the primary role of congestion control in today’s
> Internet seems to be to waste our time with round-trips (before
> transmissions are over).   Some hints about this:
> https://ieeexplore.ieee.org/document/9817041  (or:
> http://arxiv.org/abs/2206.06642 ) … and references therein, e.g.
> https://dl.acm.org/doi/10.1145/3472305.3472321
>
>
> I checked the spreadsheet on the other paper – they haven’t been updated.
>
>
> I did the same!  Disappointing, isn’t it.
>
>
> It’s a strange paper, that makes a lot of assumption regarding energy
> consumption, but you have to start somewhere. I’m surprised you’re saying
> there hasn’t been follow up to that, it’s such an important topic.
>
>
> I don’t think I said that? There are plenty of studies out there, but …
> it’s a jungle.
>
>
> I definitely will add some paragraph or section on “emergy” in the next
> version of the draft.
>
> This paper evaluates the emissions from virtual conferences – to keep in
> mind when comparing with IETF emissions from combined hybrid/in-person
> conference:
> https://forum.legacy-events.com/uploads/short-url/zmI7aFu6X6ojBESqz9IWKke4GW4.pdf
> This paper assesses the value of in-person vs virtual to be 66 times
> higher from the travel alone (but that’s 99% of the in-person energy cost!)
>
>
> Thanks!
>
>
> Toerless: was that paper cited at the workshop???
>
> Best,
>
> C.
>
>
>
> Cheers,
> Michael
>
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