Ok, let's go to the extreme. Let's say that Marek uses its genius mind to hack his ONU so that - in between bursts - it consumes nothing (nada, zip). Let's also assume that during a burst, the ONU consumes its full 11W.
Cost of polling at 1ms at night: $578K/year for the whole US (with 100% fiber adoption) Cost of polling at 50ms at night: $12K/year
Jc
inline please Is PSU = power supply unit? MH correct Are both units connected to AC power? MH correct, both connected and active Did you measure power at entrance to one PSU or both? MH power draw was measured at the power strip level. It has power draw monitoring for each phase. Is UNI port 10G? MH correct, SMF optics was used Just a single UNI? MH correct In idle state, is the ONU still being polled? How often? MH ONU was polled with 2ms cycle time
From: Marek Hajduczenia <mxhajduczenia@xxxxxxxxx> Sent: Wednesday, November 3, 2021 4:04 PM To: Glen Kramer <glen.kramer@xxxxxxxxxxxx> Cc: Hajduczenia, Marek <Marek.Hajduczenia@xxxxxxxxxxx>; Jean-Christophe Marion <jc.marion@xxxxxxxxxxxx>; Curtis (CableLabs) <c.knittle@xxxxxxxxxxxxx>; STDS-1904-4-TF@xxxxxxxxxxxxxxxxx; Kloberdans, Michael J <Michael.Kloberdans@xxxxxxxxxxx> Subject: Re: [EXTERNAL] RE: 1904.4 Consensus call
2 redundant PSUs. Pluggable PON interface and pluggable SFP+ cage on UNI side. Measurements were done with optics plugged in on both sides and traffic not running at all (idle state) or running at full swing with 64B packets. That would be best and worst case scenarios as far as I'm concerned.
That’s a big ONU! I assume this is for enterprise subscribers. Can you describe all the ports it has on PON side and on user side? Is there a built-in switch? The power target depends on specific device configuration (ports and internal functions).
Here is the data for one of the 10G-EPON ONU models we actually use in production: 7W in idle state, 11W in full swing. It is a 2 PSU unit, though, prepared for 19” rack installation
Regards
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Marek Hajduczenia, PhD | Network Architect, Distinguished Engineer (MTD), Advanced Commercial Engineering
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Hi JC,
Thank you for the good analysis. The conclusion I make is that even if we assume that every US household has a 10G PON ONU, and even if we do nothing at all, just keep the fast polling, the optics TX path contribution to power consumption is negligible. Certainly, the time cost of all of us discussing this and developing a solution will many times exceed the potential yearly savings across the entire US.
So, just controlling the TX path of the ONU optics does not make any impact. Also with the node shrink progression, the ASICs are becoming more energy efficient, which makes any external controls that turn off parts of the chip less effective or even counter-effective (if extra energy is spent to bring the chip back into an active state).
I have uploaded the EU Code of Conduct on Energy Consumption of Broadband Equipment to 1904.4 website (https://www.ieee1904.org/private/4/reference_docs/jrc125961_coc_v8.0_final.pdf)
Let’s review it and then try to gather some data from actual production ONUs (and extrapolate from 10G to 25G ONUs). We should be able to see if any measures are necessary in order to comply.
Glen
Thanks Glen, One of the action item from yesterday's discussion is about actual consumption of ONU. This gave me an idea. I went in our lab and measured the power consumption of a 10G ONU SFP+ 20Km transceiver. I am talking about just the transceiver that can be plugged into an ONU. I could measure the power consumption with Laser ON and with Laser OFF. I repeated the experiment with various brands and got consistent results. Laser | Input Voltage | Input Current | Output Optical Power ------+---------------+---------------+--------------------- OFF | 3.3V | 0.36A | -50dBm ------+---------------+---------------+--------------------- ON | 3.3V | 0.50A | +5dBm ------+---------------+---------------+--------------------- The way I measured power is simple: we have a small test board that pretty much consists of a SFP+ cage. I could read the Voltage and Current from the power supply feeding the test board. The test board itself has no active components so that we can safely neglect its own power consumption. This board is also equipped with few dip-switches controlling some input pins of the SFP+ module. In particular, it can control the SFP_TX_DIS pin which allowed me to turn laser ON and OFF. Now let's consider a very simplistic 10G EPON 'power saving' approach where all we do is slow down the polling activity at night. For our calculations, I will assume the following: - night is between 11PM and 5AM (6 hours) - Cost kWh : 12.55 cents (2021 US average) - ONU is polled at constant frequency with force report set - No traffic is going through the ONU during the night period The simplistic power saving approach is to change the polling period from 1ms (very aggressive setting) to 50ms (very slow setting). Let's now compare the cost of doing nothing (keep fast polling) and slow polling during night time. Of course the data will be about existing 10G (not 25G) and restricted to TX laser savings but it will help us getting some idea about what to expect. With a fast polling, we would have a total of 2.16E7 bursts (6h * 3600s/h * 1000burst/s) per night. Each burst being about 95TQ (based on optical overhead I selected). This means that during the night, the laser will be ON for 32.83s (2.16E7burst/night * 95TQ/burst * 16ns/TQ / 1E9s/ns) Compared to laser being OFF for that time, it corresponds to a cost of 5.29E-5cent/night (12.55cent/kWh * 3/3V * (0.50A - 0.36A) * 32.83s/night / 3600s/h / 1000W/kW) Same calculation with a slow polling, all numbers are basically divided by 50 since we poll every 50ms instead of every ms. So cost of slow polling at night is 1.06E-6cent/night compared to never turning laser ON at night. So, under the above assumptions, and aggregating the cost for 126 million US households: - Having fast polling at night costs $24.3K per year (5.29E-5cent/night * 365night/year * 126E6households / 100cent/$) - Having slow polling at night costs $486 per year (1/50 of previous number) Again, both numbers are in comparison with never turning laser at night. From this, it is not clear to me if implementing this simplistic approach is worth it, nor is it for me to judge but: - It can be implemented easily with existing equipments (Polling period is likely available to network management system). - Its impact on latency is low and controllable. 50ms polling is just an example. - Implementing full blown power saving feature seems to hit diminishing returns unless we can demonstrate that further savings (beyond TX Laser) can be implemented. Please let me know if you see a problem in my experiment or its results.
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