Azure Frontdoor health probe request increase

[mllipi]

ISSUE: Accordingly to our public documentation. AFD probe requests should be around 200 requests per minute using the default probe configuration.
https://docs.microsoft.com/en-us/azure/frontdoor/front-door-health-probes

This information is outdated, as the number of AFD probe requests jumped to around 600 requests per minute.

ASK: Please amend the documentation to reflect the actual number of probe requests Azure Frontdoor will send to backend.

IMPACT: Customer may experience issues with backend due to the volume increase in probe requests and needs to adjust the probe interval to lower the number of probe requests.

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Document Details

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• ID: f35a0b39-ab2f-ba8a-0907-e0f3a6b69135
• Version Independent ID: 0e6c8267-a911-9c6b-0522-3ec96753b3ef
• Content: Azure Front Door - backend health monitoring
• Content Source: articles/frontdoor/front-door-health-probes.md
• Service: frontdoor
• GitHub Login: @duongau
• Microsoft Alias: duau

[GitaraniSharma-MSFT]

@mllipi , thank you for your feedback. We'll review this and get back to you shortly!

[GitaraniSharma-MSFT]

@mllipi , We have assigned this to the content owner/author for review.

@duongau , I've looped you in the internal email with the Front Door PG to confirm this & update the doc accordingly.

[duongau]

Hi @mllipi, apologies on the late response here. The PG team has updated the documentation with the following statement:

Since each Azure Front Door edge POP emits health probes to your origins, the health probe volume for your origins can be quite high. The number of probes depends on your customer's traffic location and your health probe frequency. If the Azure Front Door edge POP doesn’t receive real traffic from your end users, the frequency of the health probe from the edge POP is decreased from the configured frequency. If there is customer traffic to all the Azure Front Door edge POP, the health probe volume can be high depending on your health probes frequency.

An example to roughly estimate the health probe volume per minute to your origin when using the default probe frequency of 30 seconds. The probe volume on each of your origin is equal to the number of edge POPs times two requests per minute. The probing requests will be less if there is no traffic sent to all of the edge POPs. For a list of edge locations, see https://docs.microsoft.com/en-us/azure/frontdoor/edge-locations-by-region for Azure Front Door. There could be more than one POP in each edge location.

The information above should help users find a rough estimate of how many probes their backend resources would receive. Please let me know if you have any questions. For now I will archive this issue. Thank you. #please-close