Re: [802.3_25GSMF] 802.3cc 25GSMF AdHoc Meeting Series - meeting reminder for June 7th
Hi Mark, David,
Another possibility is to make a table like the one for 100GBASE-DR that requires lower channel losses depending on the number of discrete reflections and reflectivity per reflection. If changing the transmitter reflectance from -12 dB to -26 dB is a problem, then it might be better to make a table such as the one below, keeping the maximum channel loss (6.3 dB) and maximum power budget (9 dB) unchanged. Without much thought, my initial inclination is to want to go in the direction of making something similar to Table 140-12 for the case of -12 dB Tx reflectance.
Regards,
Kohichi
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From: Mark Kimber [mailto:MKimber@xxxxxxxxxxx]
Sent: Wednesday, June 07, 2017 5:46 AM
To: David Lewis; Peter Jones (petejone)
Cc: STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx; 田村公一 Kohichi Tamura; 'Jonathan King'
Subject: RE: [802.3_25GSMF] 802.3cc 25GSMF AdHoc Meeting Series - meeting reminder for June 7th
Hi David, Pete,
I have put a few slides together to get a discussion going. Just waiting for review and approval.
Thanks,
Mark
From: David Lewis [mailto:David.Lewis@xxxxxxxxxxxx]
Sent: 05 June 2017 02:11
To: Mark Kimber; Peter Jones (petejone)
Cc: STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx>; 'kohichi.tamura (kohichi.tamura@xxxxxxxxxx<mailto:kohichi.tamura@xxxxxxxxxx>)'; 'Jonathan King'
Subject: RE: [802.3_25GSMF] 802.3cc 25GSMF AdHoc Meeting Series - meeting reminder for June 7th
Hi Mark,
A couple of comments on your message:
1. In previous NRZ SMF MPIs there was no explicit MPI penalty, just a small reflection penalty derived from the IEEE link spreadsheet model. That reflection penalty only considered the reflectance of the Tx and Rx at maximum channel insertion loss. We are talking about it now because of new knowledge gained when considering PAM4 PMDs, where MPI is a critical impairment that needs to be well controlled. As shown by Jonathan’s ad hoc presentation in king_01_25gsmf_051017, MPI is also a penalty for NRZ links and can be significant for foreseeable numbers of connectors.
2. I think the concern for MPI is at maximum loss, rather than minimum, because that is where the penalty affects the overall link budget. Jonathan’s calculations have the maximum insertion loss lumped just before the receiver.
3. For both 25GBASE-LR and -ER, we have a transmitter reflectance of -12 dB and a receiver reflectance of -26 dB. This is in line with other NRZ serial SMF PMDs, but is not what is assumed for any of the PAM4 PMDs. All of those have -26 dB at both ends in order to control the MPI penalty.
So, in addition to considering the link budget with N x -35 dB reflectances in the channel, I think we should consider requiring a -26 dB reflectance at the transmitter. In practice this would mean having fiber stubs in the Tx and Rx ferrules and would rule out free-space designs with an air gap between the laser and the output fiber.
If transceiver makers want to take keep the -12 dB Tx reflectance, we will need to add an additional MPI penalty into the -LR and -ER power budgets. I think it’s appropriate to specify maximum discrete reflectance limits using a table, similar to the one below, copied from 802.3bs D3.1.
David
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From: Mark Kimber [mailto:MKimber@xxxxxxxxxxx]<mailto:[mailto:MKimber@xxxxxxxxxxx]>
Sent: Sunday, June 04, 2017 3:00 PM
To: Peter Jones (petejone) <petejone@xxxxxxxxx<mailto:petejone@xxxxxxxxx>>
Cc: STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx>; David Lewis <David.Lewis@xxxxxxxxxxxx<mailto:David.Lewis@xxxxxxxxxxxx>>; 'kohichi.tamura (kohichi.tamura@xxxxxxxxxx<mailto:kohichi.tamura@xxxxxxxxxx>)' <kohichi.tamura@xxxxxxxxxx<mailto:kohichi.tamura@xxxxxxxxxx>>; 'Jonathan King' <jonathan.king@xxxxxxxxxxx<mailto:jonathan.king@xxxxxxxxxxx>>
Subject: RE: [802.3_25GSMF] 802.3cc 25GSMF AdHoc Meeting Series - meeting reminder for June 7th
Hi Peter,
I am on business travel at the minute so will be difficult by Wednesday. I have Jonathan’s spreadsheet downloaded but have used it in anger yet so that might need a couple of attempts to get right.
What I could do is outline potential use cases for discussion so we can get that agreed to start with. So how many reflections, etc.
Thanks,
Mark
From: Peter Jones (petejone) [mailto:petejone@xxxxxxxxx]
Sent: 04 June 2017 20:32
To: Mark Kimber
Cc: STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx>; David Lewis; 'kohichi.tamura (kohichi.tamura@xxxxxxxxxx<mailto:kohichi.tamura@xxxxxxxxxx>)'; 'Jonathan King'
Subject: RE: [802.3_25GSMF] 802.3cc 25GSMF AdHoc Meeting Series - meeting reminder for June 7th
Mark,
This feels like an offer to put together a presentation.
Can you have something ready for Wednesday?
Regards
Peter
_______________________________________________
Peter Jones Cisco Systems
Principal Engineer 560 McCarthy Blvd.
Campus Switching S/W Milpitas, CA, 95035 USA
Wrk: +1 408 525 6952 Mob: +1 408 315 8024
Email: petejone at cisco.com
About.me: about.me/petergjones<http://about.me/petergjones>
_____________________________________________
From: Mark Kimber [mailto:MKimber@xxxxxxxxxxx]<mailto:[mailto:MKimber@xxxxxxxxxxx]>
Sent: Sunday, June 4, 2017 5:05 AM
To: Peter Jones (petejone) <petejone@xxxxxxxxx<mailto:petejone@xxxxxxxxx>>; STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx>
Subject: RE: [802.3_25GSMF] 802.3cc 25GSMF AdHoc Meeting Series - meeting reminder for June 7th
Hi Peter,
My view is we should agree how many connector with appropriate return loss and also the loss and its’ placement in the link. Run some MPI sims and come up with a number.
For instance, it would be reasonable to consider 2, 4 and 6 connectors all with -35dB ORL. I think the minimum loss for ER is 10dB so we should use that as a minimum. For LR we can use something like 4dB or 5dB (same idea as used for 802.3bs and 802.3cd for 10km).
Thanks,
Mark
From: Peter Jones (petejone) [mailto:petejone@xxxxxxxxx]
Sent: 04 June 2017 02:56
To: STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx<mailto:STDS-802-3-25GSMF@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_25GSMF] 802.3cc 25GSMF AdHoc Meeting Series - meeting reminder for June 7th
Folks,
We have a meeting scheduled for Wednesday, June 7, 2017 2:00 PM-3:30 PM (UTC-08:00) Pacific Time (US & Canada).
I think the major topic that is open is comment i-38 (see below)
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Anyone got any good ideas how to progress this topic?
Please let me know by EOD Tuesday PT if you want to present on this, or any other topics.
Regards
Peter
_________________________________________________
Peter Jones
802.3cc 25GSMF Task Force Ad Hoc Chair
http://www.ieee802.org/3/cc/index.html
_________________________________________________
-----Original Appointment-----
From: Peter Jones (petejone)
Sent: Wednesday, July 6, 2016 3:41 PM
To: Peter Jones (petejone); 802. 3 25GSMF; Matt Traverso (mattrave); Ray Nering (rnering)
Cc: David Malicoat; Jeffery Maki; Jonathan King; Ed Ulrichs; derek.cassidy@xxxxxx<mailto:derek.cassidy@xxxxxx>; Dino Pozzebon; Carlo Tosetti (ctosetti); Gary Nicholl (gnicholl); mitch.h.fields@xxxxxxxxxxxx<mailto:mitch.h.fields@xxxxxxxxxxxx>; Pirooz Tooyserkani (pirooz); Greg Bradburn (grbradbu); 有本英生 / ARIMOTO，HIDEO
Subject: 802.3cc 25GSMF AdHoc Meeting Series
When: Wednesday, June 7, 2017 2:00 PM-3:30 PM (UTC-08:00) Pacific Time (US & Canada).
Where: Webex
Extending series.
-------------------------------
As announced in the F2F at the March meeting, (see http://grouper.ieee.org/groups/802/3/25GSMF/public/1603_Macau/jones_25gesmf_01_0316.pdf ), the 802.3cc 25GSMF AdHoc will re-commence weekly meetings in the Wednesday 2:00pm-3:30pm PST slot.
The goal of these meetings is to hear contributions to progress the work of the Task Force.
Please send requests for presentation time at least 24 hours before the meeting time (preferably earlier), and send presentations at least 24 hours in advance.
If there are no requests for presentation time, the meetings will be cancelled.
Regards
Peter Jones
25GSMF 802.3cc AdHoc chair
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