Metrics : How to get Enh-ACK Probing IE

[amr-ba]

Hello OpenThread Community

I'm trying to get otLinkMetricsEnhAckProbingIeReportCallback triggered, to receive Enhanced-ACK Probing, this is what I did :

1 - Configured Device1 as Leader and Device2 as Child
2 - Device1 : OtLinkMetricsConfigEnhAckProbing()
3 - Device1 : linkMetricsMgmtResponseCallback was triggered
4 - OtLinkMetricsSendLinkProbe() for iniating probing as mentioned in the Spec, we expect that linkMetricsEnhAckProbingIeReportCallback will be triggered, but it’s not the case,

my questions are:
How to configure otLinkMetricsEnhAckProbingIeReportCallback ?
Should I use OtLinkMetricsSendLinkProbe for initiating probing? and does it set the Frame Version subfield within the MAC header of the data message to 0b10 ? if it's not the case, how can I set it?

the description in the spec :
* The IEEE 802.15.4-2015 Enhanced ACK Probe feature allows the Probing Initiator detailed
* granular control over link metric queries while saving energy by reusing regular data traffic
* sequences as an alternative to sending single-purposed MLE Probe messages. The Probing
* Initiator first configures the Probing Subject via the MLE Probing Management message.
* Then the Probing Initiator sends regular data messages. Whenever the Probing Initiator
* would like to query for link metrics, it solicits an Enhanced ACK by setting the Frame
* Version subfield within the MAC header of the data message to 0b10 and the Probing
* Subject will respond with an Enhanced Acknowledgement containing link metrics.

Thanks in Advance
Amr

[Irving-cl]

Hi Amr,

Thanks for raising the question!

The process you did is correct. If the 'initiator' configures EnhAckProbing successfully at the 'subject', the 'subject' will append a LinkMetrics Report within the Enhanced-ACK sent to the 'initiator'. However, whether replying Enhanced-ACK depends on the incoming data frame. If the version of incoming data frame is 2015, then an Enhanced-ACK will be sent in reply.

Regarding your questions:

How to configure otLinkMetricsEnhAckProbingIeReportCallback

We should use the API otLinkMetricsConfigEnhAckProbing to configure the callback. I think you already did it.

Should I use OtLinkMetricsSendLinkProbe for initiating probing? and does it set the Frame Version subfield within the MAC header of
the data message to 0b10 ? if it's not the case, how can I set it?

You can use otLinkMetricsSendLinkProbe to trigger a report. But note that, as I mentioned, after an initiator configured EnhAckProbing at a subject, the subject will always append the report within the Enh-ACK whenever the initiator sends a frame of version 2015. In OT implementation, we forced all the data frames sent by the initiator to the subject to use version 2015 after EnhAckProbing is configured. See https://github.com/openthread/openthread/blob/main/src/core/thread/mesh_forwarder.cpp#L1841
So any data frame should be ok, including the link probe message.

---

To debug your issue:

• Could you first check the error code return bylinkMetricsMgmtResponseCallback? Did it succeed?
• What platform (hardware) did you run the OT stack?

[Irving-cl]

Update:

Could you also provide the traffic capture of the process?

[amr-ba]

Hi,

Sorry for the delay of my answer,

indeed linkMetricsMgmtResponseCallback returned success as status, I found that OPENTHREAD_CONFIG_MAC_CSL_TRANSMITTER_ENABLE was not enabled and so my leader device is not processing the enhancedAck,

thank you for your help,
Amr