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| 1 | +# gNMI-1.20: Telemetry: 400ZR Electrical Signal to Noise Ratio(eSNR) and Chromatic Dispersion(CD) telemetry values streaming |
| 2 | + |
| 3 | +## Summary |
| 4 | + |
| 5 | +Validate 400ZR optics module reports accurate eSNR and CD telemetry values. |
| 6 | + |
| 7 | +eSNR is defined as the electrical Signal to Noise ratio at the decision |
| 8 | +sampling point in dB |
| 9 | + |
| 10 | +Chromatic Dispersion is frequency dependent change in signal phase velocity due |
| 11 | +to fiber measured in ps/nm |
| 12 | + |
| 13 | +## Procedure |
| 14 | + |
| 15 | +* Connect two ZR interfaces using a duplex LC fiber jumper such that TX |
| 16 | + output power of one is the RX input power of the other module. Connection |
| 17 | + between the modules should pass through an optical switch that can be |
| 18 | + controlled through automation to simulate a fiber cut. |
| 19 | +* To establish a point to point ZR link ensure the following: |
| 20 | + * Both transceivers states are enabled |
| 21 | + * Both transceivers are set to a valid target TX output power |
| 22 | + example -10 dBm |
| 23 | + * Both transceivers are tuned to a valid centre frequency |
| 24 | + example 193.1 THz |
| 25 | +* With the ZR link is established as explained above, verify that the |
| 26 | + following ZR transceiver telemetry paths exist and are streamed for both |
| 27 | + the ZR optics |
| 28 | + * /terminal-device/logical-channels/channel/otn/state/esnr/instant |
| 29 | + * /terminal-device/logical-channels/channel/otn/state/esnr/avg |
| 30 | + * /terminal-device/logical-channels/channel/otn/state/esnr/min |
| 31 | + * /terminal-device/logical-channels/channel/otn/state/esnr/max |
| 32 | + * /platform/components/component/optical-channel/state/chromatic-dispersion/instant |
| 33 | + * /platform/components/component/optical-channel/state/chromatic-dispersion/avg |
| 34 | + * /platform/components/component/optical-channel/state/chromatic-dispersion/min |
| 35 | + * /platform/components/component/optical-channel/state/chromatic-dispersion/max |
| 36 | + |
| 37 | +* When the modules or the devices are still in a boot stage, they must not |
| 38 | + stream any invalid string values like "nil" or "-inf" until valid values |
| 39 | + are available for streaming. |
| 40 | + |
| 41 | +* eSNR and CD streamed values must always be of type Decimal64. |
| 42 | + When link interfaces are in down state 0 must be reported as a valid |
| 43 | + value. |
| 44 | + |
| 45 | +**Note:** For min, max, and avg values, 10 second sampling is preferred. If |
| 46 | + 10 seconds is not supported, the sampling interval used must be |
| 47 | + communicated. |
| 48 | + |
| 49 | + |
| 50 | +* Verify that the optics eSNR and CD is updated after the interface flaps. |
| 51 | + |
| 52 | + * Enable a pair of ZR interfaces on the DUT as explained above. |
| 53 | + * Verify the ZR optics eSNR and CD telemetry values are in the normal range. |
| 54 | + * Disable or shut down the interface on the DUT. |
| 55 | + * Verify with interfaces in down state both optics are streaming Decimal64 0 |
| 56 | + value for both eSNR and CD. |
| 57 | + * Re-enable the interfaces on the DUT. |
| 58 | + * Verify the ZR optics eSNR and CD telemetry values are updated to the |
| 59 | + value in the normal range again. |
| 60 | + * Typical expected value range for eSNR is 13.5 to |
| 61 | + 18 dB +/-0.1 dB. |
| 62 | + * Typical CD expected value range is 0 to 2400 ps/nm. |
| 63 | + |
| 64 | +* Verify that the optics eSNR and CD is updated after a fiber cut. |
| 65 | + |
| 66 | + * Enable a pair of ZR interfaces on the DUT as explained above. |
| 67 | + * Verify the ZR optics eSNR and CD telemetry values are in the normal |
| 68 | + range. |
| 69 | + * Simulate a fiber cut using the optical switch that sits in-between the |
| 70 | + DUT ports. |
| 71 | + * Verify with link in down state due to fiber cut both optics are streaming |
| 72 | + Decimal64 0 value for both eSNR and CD. |
| 73 | + * Re-enable the optical switch connection to clear the fiber cut fault. |
| 74 | + * Verify the ZR optics eSNR and CD telemetry values are updated to the value in the normal |
| 75 | + range again. |
| 76 | + * Typical expected value range for eSNR is 13.5 to |
| 77 | + 18 dB +/-0.1 dB. |
| 78 | + * Typical CD expected value range is 0 to 2400 ps/nm. |
| 79 | + |
| 80 | +## Config Parameter coverage |
| 81 | + |
| 82 | +* /components/component/transceiver/config/enabled |
| 83 | + |
| 84 | +## Telemetry Parameter coverage |
| 85 | + |
| 86 | +* /terminal-device/logical-channels/channel/otn/state/esnr/instant |
| 87 | +* /terminal-device/logical-channels/channel/otn/state/esnr/avg |
| 88 | +* /terminal-device/logical-channels/channel/otn/state/esnr/min |
| 89 | +* /terminal-device/logical-channels/channel/otn/state/esnr/max |
| 90 | +* /platform/components/component/optical-channel/state/chromatic-dispersion/instant |
| 91 | +* /platform/components/component/optical-channel/state/chromatic-dispersion/avg |
| 92 | +* /platform/components/component/optical-channel/state/chromatic-dispersion/min |
| 93 | +* /platform/components/component/optical-channel/state/chromatic-dispersion/max |
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