CloudWatch metrics for your VPCs - Amazon Virtual Private Cloud
NAU metrics and dimensionsEnable or disable NAU monitoringNAU CloudWatch alarm example
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CloudWatch metrics for your VPCs

Amazon VPC publishes data about your VPCs to Amazon CloudWatch. You can retrieve statistics about your VPCs as an ordered set of time-series data, known as metrics. Think of a metric as a variable to monitor and the data as the value of that variable over time. For more information, see the Amazon CloudWatch User Guide.

NAU metrics and dimensions

Network Address Usage (NAU) is a metric applied to resources in your virtual network to help you plan for and monitor the size of your VPC. There is no cost to monitor NAU. Monitoring NAU is helpful because if you exhaust the NAU or peered NAU quotas for your VPC, you can't launch new EC2 instances or provision new resources, such as Network Load Balancers, VPC endpoints, Lambda functions, transit gateway attachments, and NAT gateways.

If you've enabled Network Address Usage monitoring for a VPC, Amazon VPC sends metrics related to NAU to Amazon CloudWatch. The size of a VPC is measured by the number of Network Address Usage (NAU) units that the VPC contains.

You can use these metrics to understand the rate of your VPC growth, forecast when your VPC will reach its size limit, or create alarms when size thresholds are crossed.

The AWS/EC2namespace includes the following metrics for monitoring NAU.

Metric Description
NetworkAddressUsage

The NAU count per VPC.

Reporting criteria

  • Every 24 hours.

Dimensions

  • Name: Per-VPC Metrics, Value: The VPC ID.
NetworkAddressUsagePeered The NAU count for the VPC and all VPCs that it's peered with.

Reporting criteria

  • Every 24 hours.

Dimensions

  • Name: Per-VPC Metrics, Value: The VPC ID.

The AWS/Usagenamespace includes the following metrics for monitoring NAU.

Metric Description
ResourceCount

The NAU count per VPC.

Reporting criteria

  • Every 24 hours.

Dimensions

  • Name: Service, Value: EC2

  • Name: Type, Value: Resource

  • Name: Resource, Value: The VPC ID.

  • Name: Class, Value: NetworkAddressUsage
ResourceCount

The NAU count for the VPC and all VPCs that it's peered with.

Reporting criteria

  • Every 24 hours.

Dimensions

  • Name: Service, Value: EC2

  • Name: Type, Value: Resource

  • Name: Resource, Value: The VPC ID.

  • Name: Class, Value: NetworkAddressUsagePeered
ResourceCount

A combined view of NAU usage across VPCs.

Reporting criteria

  • Every 24 hours.

Dimensions

  • Name: Service, Value: EC2

  • Name: Type, Value: Resource

  • Name: Resource, Value: VPC

  • Name: Class, Value: NetworkAddressUsage
ResourceCount

A combined view of NAU usage across peered VPCs.

Reporting criteria

  • Every 24 hours.

Dimensions

  • Name: Service, Value: EC2

  • Name: Type, Value: Resource

  • Name: Resource, Value: VPC

  • Name: Class, Value: NetworkAddressUsagePeered

Enable or disable NAU monitoring

To view NAU metrics in CloudWatch, you must first enable monitoring on each VPC to monitor.

To enable or disable monitoring NAU

  1. Open the Amazon VPC console at https://console.amazonaws.cn/vpc/.

  2. In the navigation pane, choose Your VPCs.

  3. Select the check box for the VPC.

  4. Select Actions, Edit VPC settings.

  5. Do one of the following:

    • To enable monitoring, select Network mapping units metrics settings, Enable network address usage metrics.

    • To disable monitoring, clear Network mapping units metrics settings, Enable network address usage metrics.

To enable or disable monitoring using the command line

NAU CloudWatch alarm example

You can use the following Amazon CLI command and example .json to create an Amazon CloudWatch alarm and SNS notification that tracks NAU utilization of the VPC with 50,000 NAUs as the threshold. This sample requires you to first create an Amazon SNS topic. For more information, see Getting started with Amazon SNS in the Amazon Simple Notification Service Developer Guide.

aws cloudwatch put-metric-alarm --cli-input-json file://nau-alarm.json

The following is an example of nau-alarm.json.

{
    "Namespace": "AWS/EC2",
    "MetricName": "NetworkAddressUsage",
    "Dimensions": [{
        "Name": "Per-VPC Metrics",
        "Value": "vpc-0123456798"
    }],
    "AlarmActions": ["arn:aws:sns:us-west-1:123456789012:my_sns_topic"],
    "ComparisonOperator": "GreaterThanThreshold",
    "Period": 86400,
    "EvaluationPeriods": 1,
    "Threshold": 50000,
    "AlarmDescription": "Tracks NAU utilization of the VPC with 50k NAUs as the threshold",
    "AlarmName": "VPC NAU Utilization",
    "Statistic": "Maximum"
}