Matt,
This is an old chestnut.
You said: “So a value of OK is not determined simply by detecting a power level of greater than or equal to -30 dBm, it’s also having a compliant 100GBASE-R signal input"
No, this is not correct. The intent of this table is that if you want to guarantee that the device sets SIGNAL_DETECT to OK, then you need to input a signal that is greater than -30 dBm and is a compliant 100GBASE-R signal. If you input a signal that is greater than -30 dBm and is not a compliant 100GBASE-R signal (e.g. CW light or a 10 MHz square wave) the device is allowed to set SIGNAL_DETECT to either OK or FAIL.
This is clarified in the text above the table: “The PMD receiver is not required to verify whether a compliant 100GBASE-R signal is being received.”
Regards,
Pete Anslow (pete@xxxxxxxxxxxxxxx)
From: Matthew Schmitt <m.schmitt@xxxxxxxxxxxxx>
Sent: 19 June 2020 01:45
To: STDS-802-3-DWDM@xxxxxxxxxxxxxxxxx
Subject: [802.3_DWDM] Signal Detect follow-up question
Following up on John’s presentation from last week, I was looking at the text in the current draft, and had a question I am having difficulty finding the answer to within the 802.3 specification.
As it stands currently, the text in 154.5.4 states that SIGNAL_DETECT parameter maps to the SIGNAL_OK parameter (which I’m assuming means that SIGNAL_DETECT OK results in SIGNAL_OK of OK). In Table 154-5, it defines a SIGNAL_DETECT value of OK to be the following:
[(Optical power at TP3 ³ minimum average input power [unamplified] in Table 154–9
AND
(compliant 100GBASE-R)]
So a value of OK is not determined simply by detecting a power level of greater than or equal to -30 dBm, it’s also having a compliant 100GBASE-R signal input (note that I’m inserting the words “signal input”, since they appear in a similar situation in Table 88-4, although not in Table 154-5).
My question then is this: is there a common understanding of what “compliant 100GBASE-R” (or “compliant 100GBASE-R signal input”) means in this particular case? If it means that you need to be able to decode an apparently valid signal, wouldn’t that address the issue of a false positive due to an amplifier caused high noise floor? Or is the meaning something completely different?
Thanks for any help in better understanding this.
Matt
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