CloudWatch metrics for your Network Load Balancer - Elastic Load Balancing
Network Load Balancer metricsMetric dimensions for Network Load BalancersStatistics for Network Load Balancer metricsView CloudWatch metrics for your load balancer

CloudWatch metrics for your Network Load Balancer

Elastic Load Balancing publishes data points to Amazon CloudWatch for your load balancers and your targets. 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. For example, you can monitor the total number of healthy targets for a load balancer over a specified time period. Each data point has an associated time stamp 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.

Elastic Load Balancing reports metrics to CloudWatch only when requests are flowing through the load balancer. If there are requests flowing through the load balancer, Elastic Load Balancing measures and sends its metrics in 60-second intervals. If there are no requests flowing through the load balancer or no data for a metric, the metric is not reported. For Network Load Balancers with security groups, traffic rejected by the security groups is not captured in the CloudWatch metrics.

For more information, see the Amazon CloudWatch User Guide.

Network Load Balancer metrics

The AWS/NetworkELB namespace includes the following metrics.

Metric Description
ActiveFlowCount

The total number of concurrent flows (or connections) from clients to targets. This metric includes connections in the SYN_SENT and ESTABLISHED states. TCP connections are not terminated at the load balancer, so a client opening a TCP connection to a target counts as a single flow.

Reporting criteria: Always reported.

Statistics: The most useful statistics are Average, Maximum, and Minimum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ActiveFlowCount_TCP

The total number of concurrent TCP flows (or connections) from clients to targets. This metric includes connections in the SYN_SENT and ESTABLISHED state. TCP connections are not terminated at the load balancer, so a client opening a TCP connection to a target counts as a single flow.

Reporting criteria: There is a nonzero value

Statistics: The most useful statistics are Average, Maximum, and Minimum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ActiveFlowCount_TLS

The total number of concurrent TLS flows (or connections) from clients to targets. This metric includes connections in the SYN_SENT and ESTABLISHED state.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistics are Average, Maximum, and Minimum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ActiveFlowCount_UDP

The total number of concurrent UDP flows (or connections) from clients to targets.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistics are Average, Maximum, and Minimum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ClientTLSNegotiationErrorCount

The total number of TLS handshakes that failed during negotiation between a client and a TLS listener.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer
ConsumedLCUs

The number of load balancer capacity units (LCU) used by your load balancer. You pay for the number of LCUs that you use per hour. For more information, see Elastic Load Balancing Pricing.

Reporting criteria: Always reported.

Statistics: All

Dimensions

  • LoadBalancer
ConsumedLCUs_TCP

The number of load balancer capacity units (LCU) used by your load balancer for TCP. You pay for the number of LCUs that you use per hour. For more information, see Elastic Load Balancing Pricing.

Reporting criteria: There is a nonzero value.

Statistics: All

Dimensions

  • LoadBalancer
ConsumedLCUs_TLS

The number of load balancer capacity units (LCU) used by your load balancer for TLS. You pay for the number of LCUs that you use per hour. For more information, see Elastic Load Balancing Pricing.

Reporting criteria: There is a nonzero value.

Statistics: All

Dimensions

  • LoadBalancer
ConsumedLCUs_UDP

The number of load balancer capacity units (LCU) used by your load balancer for UDP. You pay for the number of LCUs that you use per hour. For more information, see Elastic Load Balancing Pricing.

Reporting criteria: There is a nonzero value.

Statistics: All

Dimensions

  • LoadBalancer
HealthyHostCount

The number of targets that are considered healthy. This metric does not include any Application Load Balancers registered as targets.

Reporting criteria: Reported if health checks are enabled.

Statistics: The most useful statistics are Maximum and Minimum.

Dimensions

  • LoadBalancer, TargetGroup

  • AvailabilityZone, LoadBalancer, TargetGroup
NewFlowCount

The total number of new flows (or connections) established from clients to targets in the time period.

Reporting criteria: Always reported.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
NewFlowCount_TCP

The total number of new TCP flows (or connections) established from clients to targets in the time period.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
NewFlowCount_TLS

The total number of new TLS flows (or connections) established from clients to targets in the time period.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
NewFlowCount_UDP

The total number of new UDP flows (or connections) established from clients to targets in the time period.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
PeakPacketsPerSecond

Highest average packet rate (packets processed per second), calculated every 10 seconds during the sampling window. This metric includes health check traffic.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Maximum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
PortAllocationErrorCount

The total number of ephemeral port allocation errors during a client IP translation operation. A non-zero value indicates dropped client connections.

Note: Network Load Balancers support 55,000 simultaneous connections or about 55,000 connections per minute to each unique target (IP address and port) when performing client address translation. To fix port allocation errors, add more targets to the target group.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ProcessedBytes

The total number of bytes processed by the load balancer, including TCP/IP headers. This count includes traffic to and from targets, minus health check traffic.

Reporting criteria: Always reported.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ProcessedBytes_TCP

The total number of bytes processed by TCP listeners.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ProcessedBytes_TLS

The total number of bytes processed by TLS listeners.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ProcessedBytes_UDP

The total number of bytes processed by UDP listeners.

Reporting criteria: There is a nonzero value

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
ProcessedPackets

The total number of packets processed by the load balancer. This count includes traffic to and from targets, including health check traffic.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
SecurityGroupBlockedFlowCount_Inbound_ICMP

The number of new ICMP messages rejected by the inbound rules of the load balancer security groups.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
SecurityGroupBlockedFlowCount_Inbound_TCP

The number of new TCP flows rejected by the inbound rules of the load balancer security groups.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
SecurityGroupBlockedFlowCount_Inbound_UDP

The number of new UDP flows rejected by the inbound rules of the load balancer security groups.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
SecurityGroupBlockedFlowCount_Outbound_ICMP

The number of new ICMP messages rejected by the outbound rules of the load balancer security groups.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
SecurityGroupBlockedFlowCount_Outbound_TCP

The number of new TCP flows rejected by the outbound rules of the load balancer security groups.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
SecurityGroupBlockedFlowCount_Outbound_UDP

The number of new UDP flows rejected by the outbound rules of the load balancer security groups.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
TargetTLSNegotiationErrorCount

The total number of TLS handshakes that failed during negotiation between a TLS listener and a target.

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer
TCP_Client_Reset_Count

The total number of reset (RST) packets sent from a client to a target. These resets are generated by the client and forwarded by the load balancer.

Reporting criteria: Always reported.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
TCP_ELB_Reset_Count

The total number of reset (RST) packets generated by the load balancer. For more information, see Troubleshooting.

Reporting criteria: Always reported.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
TCP_Target_Reset_Count

The total number of reset (RST) packets sent from a target to a client. These resets are generated by the target and forwarded by the load balancer.

Reporting criteria: Always reported.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer
UnHealthyHostCount

The number of targets that are considered unhealthy. This metric does not include any Application Load Balancers registered as targets.

Reporting criteria: Reported if health checks are enabled.

Statistics: The most useful statistics are Maximum and Minimum.

Dimensions

  • LoadBalancer, TargetGroup

  • AvailabilityZone, LoadBalancer, TargetGroup
UnhealthyRoutingFlowCount

The number of flows (or connections) that are routed using the routing failover action (fail open).

Reporting criteria: There is a nonzero value.

Statistics: The most useful statistic is Sum.

Dimensions

  • LoadBalancer

  • AvailabilityZone, LoadBalancer

Metric dimensions for Network Load Balancers

To filter the metrics for your load balancer, use the following dimensions.

Dimension Description
AvailabilityZone

Filters the metric data by Availability Zone.
LoadBalancer

Filters the metric data by load balancer. Specify the load balancer as follows: net/load-balancer-name/1234567890123456 (the final portion of the load balancer ARN).
TargetGroup

Filters the metric data by target group. Specify the target group as follows: targetgroup/target-group-name/1234567890123456 (the final portion of the target group ARN).

Statistics for Network Load Balancer metrics

CloudWatch provides statistics based on the metric data points published by Elastic Load Balancing. Statistics are metric data aggregations over specified period of time. When you request statistics, the returned data stream is identified by the metric name and dimension. A dimension is a name/value pair that uniquely identifies a metric. For example, you can request statistics for all the healthy EC2 instances behind a load balancer launched in a specific Availability Zone.

The Minimum and Maximum statistics reflect the minimum and maximum values of the data points reported by the individual load balancer nodes in each sampling window. Increases in the maximum of HealthyHostCount correspond to decreases in the minimum of UnHealthyHostCount. It's recommended to monitor maximum HealthyHostCount, invoking the alarm when the maximum HealthyHostCount falls below your required minimum, or being 0. This can help in identifying when your targets have become unhealthy. It's also recommended to monitor minimum UnHealthyHostCount, invoking the alarm when the minimum UnHealthyHostCount rises above 0. This allows you to become aware when there are no longer any registered targets.

The Sum statistic is the aggregate value across all load balancer nodes. Because metrics include multiple reports per period, Sum is only applicable to metrics that are aggregated across all load balancer nodes.

The SampleCount statistic is the number of samples measured. Because metrics are gathered based on sampling intervals and events, this statistic is typically not useful. For example, with HealthyHostCount, SampleCount is based on the number of samples that each load balancer node reports, not the number of healthy hosts.

View CloudWatch metrics for your load balancer

You can view the CloudWatch metrics for your load balancers using the Amazon EC2 console. These metrics are displayed as monitoring graphs. The monitoring graphs show data points if the load balancer is active and receiving requests.

Alternatively, you can view metrics for your load balancer using the CloudWatch console.

To view metrics using the Amazon EC2 console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

  2. To view metrics filtered by target group, do the following:

    1. In the navigation pane, choose Target Groups.

    2. Select your target group and choose Monitoring.

    3. (Optional) To filter the results by time, select a time range from Showing data for.

    4. To get a larger view of a single metric, select its graph.

  3. To view metrics filtered by load balancer, do the following:

    1. In the navigation pane, choose Load Balancers.

    2. Select your load balancer and choose Monitoring.

    3. (Optional) To filter the results by time, select a time range from Showing data for.

    4. To get a larger view of a single metric, select its graph.

To view metrics using the CloudWatch console

  1. Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

  2. In the navigation pane, choose Metrics.

  3. Select the NetworkELB namespace.

  4. (Optional) To view a metric across all dimensions, type its name in the search field.

To view metrics using the AWS CLI

Use the following list-metrics command to list the available metrics:

aws cloudwatch list-metrics --namespace AWS/NetworkELB
To get the statistics for a metric using the AWS CLI

Use the following get-metric-statistics command get statistics for the specified metric and dimension. Note that CloudWatch treats each unique combination of dimensions as a separate metric. You can't retrieve statistics using combinations of dimensions that were not specially published. You must specify the same dimensions that were used when the metrics were created.

aws cloudwatch get-metric-statistics --namespace AWS/NetworkELB \
--metric-name UnHealthyHostCount --statistics Average  --period 3600 \
--dimensions Name=LoadBalancer,Value=net/my-load-balancer/50dc6c495c0c9188 \
Name=TargetGroup,Value=targetgroup/my-targets/73e2d6bc24d8a067 \
--start-time 2017-04-18T00:00:00Z --end-time 2017-04-21T00:00:00Z

The following is example output:

{
    "Datapoints": [
        {
            "Timestamp": "2017-04-18T22:00:00Z",
            "Average": 0.0,
            "Unit": "Count"
        },
        {
            "Timestamp": "2017-04-18T04:00:00Z",
            "Average": 0.0,
            "Unit": "Count"
        },
        ...
    ],
    "Label": "UnHealthyHostCount"
}