Azure Virtual Network NAT metrics

Azure Virtual Network NAT gateway resources provide multi-dimensional metrics. You can use these metrics to observe the operation and for troubleshooting. Alerts can be configured for critical issues such as SNAT exhaustion.

Figure depicts a NAT gateway resource that consumes all IP addresses for a public IP prefix and directs that traffic to and from two subnets of virtual machines and a virtual machine scale set.

Figure: Virtual Network NAT for outbound to Internet

Metrics

NAT gateway resources provide the following multi-dimensional metrics in Azure Monitor:

Metric Description Recommended Aggregation Dimensions
Bytes Bytes processed inbound and outbound Sum Direction (In; Out), Protocol (6 TCP; 17 UDP)
Packets Packets processed inbound and outbound Sum Direction (In; Out), Protocol (6 TCP; 17 UDP)
Dropped packets Packets dropped by the NAT gateway Sum /
SNAT Connection Count State transitions per interval Sum Connection State, Protocol (6 TCP; 17 UDP)
Total SNAT connection count Current active SNAT connections (~ SNAT ports in use) Sum Protocol (6 TCP; 17 UDP)
Datapath availability (Preview) Availability of the data path of the NAT gateway. Used to determine whether the NAT gateway endpoints are available for outbound traffic flow. Avg Availability (0, 100)

Alerts

Alerts for metrics can be configured in Azure Monitor for each of the preceding metrics.

Limitations

Resource Health isn't supported.

Next steps