Amazon Virtual Private Cloud
Transit Gateways

CloudWatch Metrics for Your Transit Gateways

Amazon VPC publishes data points to Amazon CloudWatch for your transit gateways. CloudWatch enables you to retrieve statistics about those data points as an ordered set of time series data, known as metrics. Think of a metric as a variable to monitor, and the data points as the values of that variable over time. Each data point has an associated timestamp and an optional unit of measurement.

You can use metrics to verify that your system is performing as expected. For example, you can create a CloudWatch alarm to monitor a specified metric and initiate an action (such as sending a notification to an email address) if the metric goes outside what you consider an acceptable range.

Amazon VPC reports metrics to CloudWatch only when requests are flowing through the transit gateway. If there are requests flowing through the transit gateway, Amazon VPC measures and sends its metrics in 60-second intervals. If there are no requests flowing through the transit gateway or no data for a metric, the metric is not reported.

For more information, see the Amazon CloudWatch User Guide.

Transit Gateway Metrics

The AWS/TransitGateway namespace includes the following metrics.

Metric Description

The number of bytes received by the transit gateway.


The number of bytes sent from the transit gateway.


The number of packets received by the transit gateway.


The number of packets sent by the transit gateway.


The number of packets dropped because they matched a blackhole route.


The number of packets dropped because they did not match a route.

Metric Dimensions for Transit Gateways

To filter the metrics for your transit gateways, use the following dimensions.

Dimension Description

Filters the metric data by transit gateway.