CloudWatch metrics for your transit gateways

Amazon VPC publishes data points to Amazon CloudWatch for your transit gateways and transit gateway attachments. 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 measures and sends its metrics to CloudWatch in 60-second intervals.

For more information, see the Amazon CloudWatch User Guide.

Transit gateway metrics

The AWS/TransitGateway namespace includes the following metrics.

Metric	Description
BytesIn	The number of bytes received by the transit gateway.
BytesOut	The number of bytes sent from the transit gateway.
PacketsIn	The number of packets received by the transit gateway.
PacketsOut	The number of packets sent by the transit gateway.
PacketDropCountBlackhole	The number of packets dropped because they matched a blackhole route.
PacketDropCountNoRoute	The number of packets dropped because they did not match a route.

Attachment-level metrics

The following metrics are available for transit gateway attachments. Most attachment types are supported. All attachment metrics are published to the transit gateway owner's account. Individual attachment metrics are also published to the attachment owner's account (the attachment owner can only view metrics for their own attachment).

Metric	Description
BytesIn	The number of bytes received by the transit gateway from the attachment.
BytesOut	The number of bytes sent from the transit gateway to the attachment.
PacketsIn	The number of packets received by the transit gateway from the attachment.
PacketsOut	The number of packets sent by the transit gateway to the attachment.
PacketDropCountBlackhole	The number of packets dropped because they matched a blackhole route on the transit gateway attachment.
PacketDropCountNoRoute	The number of packets dropped because they did not match a route on the transit gateway attachment.

Transit gateway multicast metrics

The following metrics for multicast traffic on transit gateways.

Metric	Description
NumberofMulticastDomains	The number of multicast domains configured on the transit gateway.
NumberofMulticastGroupMembers	The number of multicast group members configured onthe transit gateway.

Multicast attachment-level metrics

The following multicast metrics are available for transit gateway VPC attachments. All multicast attachment metrics are published to the transit gateway owner's account. Individual multicast attachment metrics are also published to the attachment owner's account (the attachment owner can only view metrics for their own attachment).

Metric	Description
MulticastBytesIn	The number of multicast bytes received by the transit gateway.
MulticastBytesOut	The number of multicast bytes sent from the transit gateway.
MulticastPacketsIn	The number of multicast packets received by the transit gateway.
MulticastPacketsOut	The number of multicast packets sent by the transit gateway.
MulticastPacketDropCount	The number of multicast packets dropped.
IGMPJoins	The number of IGMP Join messages received by the transit gateway.
IGMPReceives	The number of IGMP Leave messages received by the transit gateway.
IGMPQueries	The number of IGMP Query messages received by the transit gateway.

Metric dimensions for transit gateways

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

Dimension	Description
TransitGateway	Filters the metric data by transit gateway.
TransitGatewayAttachment	Filters the metric data by transit gateway attachment.