Hi Haoyu,

thank you for your comments.  A couple of quick replies:

Re: 1) Clearly normalization is important and the challenge there is to come up with metrics which are both useful and straightforward to implement.  IMHO the starting point will include the "raw" metrics; applying any formulas or factors should be done as part of second-order metrics.  As for separating out how much carbon footprint should be attributed to a computation task versus a networking task for devices that perform in-networking computing, I am not sure this will always be practical.  However, you could in fact use the metrics that are proposed in the draft to account for that at the networking level.   Here you look at the overall energy consumption or the network as a whole, not just the sum of individual devices.  This will allow you to account for "hidden" polluters etc, and use that to apply some factor or "tax" to come up with the true holistic picture.  In cases where you have networking devices that have a large carbon footprint, but that obviate the need for separate devices that would otherwise not be accounted for, this factor will be a lot smaller than would otherwise be the case.

Re: 2) The intent here is to focus on the "what" not on the "how". That being said I think there are a number of things that can be done to measure or at least estimate these.  A simple example would, for example, determine what fraction of a device's traffic volume can be attributed to a particular flow (this is straightforward), then apply that fraction to the carbon footprint of the device overall to determine the flow's share of it.

Re: 3) Of course if you send many bits you divide the share among them.  What is meant here is the incremental cost of sending a bit.  If you sent just a single bit, that would involve a high incremental cost (which will be incurred even if you send no further bit); if you were to send a second bit immediately after that, that one would involve a very low incremental cost.

Cheers

--- Alex


On 3/9/2023 11:29 AM, Haoyu Song wrote:
Hi Alex,

This is an interesting read. Here I provide some comments and observations.
1. I think the energy consumption metrics on equipment is more meaningful when 
it's normalized to the device's capacity and capability. For example, energy 
per bit can be used to compare which is greener between two devices if they 
offer the same function. On the other hand, if a device does more processing 
(e.g., in network computing), it's likely it will consume more energy, but it 
also makes the overall solution more efficient, so it's still greener in this 
sense.
2. The flow and path energy metrics is interesting but I wonder how it can be 
measured in reality? If this is doable, then perhaps application/job level 
energy consumption metrics should also be included (e.g., in HPC DCNs, a job 
may involves multiple flows and multiple paths). This level of granularity may 
be more preferred in evaluating  different solution architectures.
3. In section 3.1.1, it seems unfair to attribute the cost to only the first 
bit. It's meaningless to send only one bit anyway so the cost should be shared 
by all the bits.:)

Best regards,
Haoyu

-----Original Message-----
From: OPSAWG <opsawg-boun...@ietf.org> On Behalf Of Alexander L Clemm
Sent: Wednesday, March 8, 2023 5:35 PM
To: opsawg@ietf.org; n...@irtf.org
Cc: draft-cx-green-metr...@ietf.org
Subject: [OPSAWG] New revision of "Green Networking Metrics" 
(draft-cx-green-metrics)

Hi,

we just posted an updated revision of "Green Networking Metrics"
(https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-cx-green-metrics%2F&data=05%7C01%7Chaoyu.song%40futurewei.com%7C2643e0c419c1408dad4a08db203e9a42%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C638139225483790907%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=USheN9sfG%2FwDm8Yy9aTy20SacMv%2B1Zd6hbiiPP63iHg%3D&reserved=0),
 including various editorial improvements and incorporating highly useful feedback and suggestions 
from a number of people including Eve Schooler, Alexandru Petrescu, and Michael Welzl.  The draft 
defines a set of "green" networking metrics that will be useful as basis for management and 
control applications that aim to reduce carbon footprint and hence require visibility into such 
metrics.

We believe that in terms of scope, this draft falls into the intersection of 
opsawg and nmrg interest and we hope to have the opportunity to present at IETF 
116 in Yokohama, hence we are crossposting to both groups.  Personally I 
believe that opsawg may be the most suitable landing spot as the draft can be 
easily operationalized and is not as much concerned with open-ended research 
questions, but that is of course where we would appreciate feedback from the 
groups.  Once a decision is made for the proper landing spot, hopefully 
immediately following IETF 116, we will post a new revision under the 
respective working group.

FYI, here is the abstract of the draft:
This document explains the need for network instrumentation that allows to assess the 
power consumption, energy efficiency, and carbon footprint associated with a network, its 
equipment, and the services that are provided over it.  It also suggests a set of related 
metrics that, when provided visibility into, can help to optimize a network's energy 
efficiency and "greenness".

On behalf of the coauthors
--- Alex

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