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Copy file name to clipboardExpand all lines: articles/load-balancer/load-balancer-standard-diagnostics.md
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@@ -80,8 +80,10 @@ To configure alerts:
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>[!NOTE]
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>Alert condition configuration window will show time series for signal history. There is an option to filter this time series by dimensions such as Backend IP. This will filter the time series graph but **not** the alert itself. You cannot configure alerts for specific Backend IP addresses.
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#### Is the data path up and available for my load balancer VIP?
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<details>
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<summary>Click to expand!</summary>
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The VIP availability metric describes the health of the data path within the region to the compute host where your VMs are located. The metric is a reflection of the health of the Azure infrastructure. You can use the metric to:
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- Monitor the external availability of your service
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For diagnostic purposes, you can use the [Data Path Availability metric together with the health probe status](#vipavailabilityandhealthprobes).
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Use **Average** as the aggregation for most scenarios.
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</details>
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#### Are the back-end instances for my VIP responding to probes?
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<summary>Click to expand!</summary>
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The health probe status metric describes the health of your application deployment as configured by you when you configure the health probe of your load balancer. The load balancer uses the status of the health probe to determine where to send new flows. Health probes originate from an Azure infrastructure address and are visible within the guest OS of the VM.
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To get the health probe status for your Standard Load Balancer resources:
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- Your probe is not permitted by the Network Security Group, the VM's guest OS firewall, or the application layer filters.
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Use **Average** as the aggregation for most scenarios.
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</details>
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#### How do I check my outbound connection statistics?
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<summary>Click to expand!</summary>
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The SNAT connections metric describes the volume of successful and failed connections for [outbound flows](https://aka.ms/lboutbound).
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A failed connections volume of greater than zero indicates SNAT port exhaustion. You must investigate further to determine what may be causing these failures. SNAT port exhaustion manifests as a failure to establish an [outbound flow](https://aka.ms/lboutbound). Review the article about outbound connections to understand the scenarios and mechanisms at work, and to learn how to mitigate and design to avoid SNAT port exhaustion.
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#### How do I check my SNAT port usage and allocation?
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<summary>Click to expand!</summary>
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The SNAT Usage metric indicates how many unique flows are established between an internet source and a backend VM or virtual machine scale set that is behind a load balancer and does not have a public IP address. By comparing this with the SNAT Allocation metric, you can determine if your service is experiencing or at risk of SNAT exhaustion and resulting outbound flow failure.
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If your metrics indicate risk of [outbound flow](https://aka.ms/lboutbound) failure, reference the article and take steps to mitigate this to ensure service health.
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*Figure: TCP SNAT port usage per backend instance*
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</details>
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#### How do I check inbound/outbound connection attempts for my service?
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<summary>Click to expand!</summary>
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A SYN packets metric describes the volume of TCP SYN packets, which have arrived or were sent (for [outbound flows](https://aka.ms/lboutbound)) that are associated with a specific front end. You can use this metric to understand TCP connection attempts to your service.
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Use **Total** as the aggregation for most scenarios.
#### <aname = "vipavailabilityandhealthprobes"></a>How do I diagnose my load balancer deployment?
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<summary>Click to expand!</summary>
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By using a combination of the VIP availability and health probe metrics on a single chart you can identify where to look for the problem and resolve the problem. You can gain assurance that Azure is working correctly and use this knowledge to conclusively determine that the configuration or application is the root cause.
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You can use health probe metrics to understand how Azure views the health of your deployment as per the configuration you have provided. Looking at health probes is always a great first step in monitoring or determining a cause.
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- The health probe status (DIP availability), indicated by the purple trace, is at 0 percent at the beginning of the chart. The circled area in green highlights where the health probe status (DIP availability) became healthy, and at which point the customer's deployment was able to accept new flows.
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The chart allows customers to troubleshoot the deployment on their own without having to guess or ask support whether other issues are occurring. The service was unavailable because health probes were failing due to either a misconfiguration or a failed application.
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</details>
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## <aname = "ResourceHealth"></a>Resource health status
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