Oracle Cloud Infrastructure Documentation

NAT Gateway Metrics

Learn how you can monitor the health, capacity, and performance of your NAT gateways by using metrics, alarms, and notifications.

This topic describes the metrics emitted by the metric namespace oci_nat_gateway. For more information, see Monitoring and Notifications.

Overview of Metrics: oci_nat_gateway

A NAT gateway is used to give an entire private network access to the internet without assigning each host a public IPv4 address. The hosts can start connections to the internet and receive responses, but not receive inbound connections initiated from the internet.

The available metrics help you decide quickly if your NAT gateway is up, how much data is flowing through the gateway, and if packets are being dropped for unexpected errors.

  • Traffic to and from the NAT gateway: Per-gateway traffic levels (packets and bytes), which can help you identify meaningful increases or decreases in traffic coming in and out of the gateway.
  • Packets dropped: Per-gateway drops (dropped packets), which can help you identify changes in traffic caused by issues such as NAT port exhaustion.

Required IAM Policy

To monitor resources, you must be granted the required type of access in a policy  written by an administrator, whether you're using the Console or the REST API with an SDK, CLI, or other tool. The policy must give you access to both the monitoring services and the resources being monitored. If you try to perform an action and get a message that you don't have permission or are unauthorized, contact the administrator to find out what type of access you were granted and which compartment  you need to work in. For more information about user authorizations for monitoring, see IAM Policies.

Available Metrics: oci_nat_gateway

The metrics listed in the following table are automatically available for each NAT gateway that you create. You don't need to enable monitoring to get these metrics.

You also can use the Monitoring service to create custom queries. See Building Metric Queries.

Each metric includes one or more of the following dimensions:

  • RESOURCEID: The OCID  of the NAT gateway.
  • DROPTYPE: The type of packet drop:
    • noPorts: Packets dropped because of NAT port exhaustion.
    • throttle: Packets dropped because of throttling at NAT gateway.
    • other: Packets invalid for one of the following reasons:
      • Packet TCP data indicates a TCP connection that's already closed.
      • Packet TCP data indicates the connection wasn't established before.
      • Packet size exceeds MTU.
      • Packet destination is unreachable.
Metric Metric Display Name Unit Description Dimensions
BytesToNATgw Bytes from OCI resources to NAT gateway. Bytes Number of bytes sent from Oracle Cloud Infrastructure (OCI) resources to NAT gateway. resourceId
BytesFromNATgw Bytes from NAT gateway to OCI resources. Bytes Number of bytes sent from NAT gateway to OCI resources.
PacketsToNATgw Packets from OCI resources to NAT gateway. Packets Number of packets sent from OCI resources to NAT gateway.
PacketsFromNATgw Packets from NAT gateway to OCI resources. Packets Number of packets sent from NAT gateway to OCI resources.
highPortUsageWatermark High Port Usage for SNAT on NAT gateway. N/A

A binary metrics to report thresh-hold-based high-watermark-usage of SNAT ports among different destinations.

The threshold is set to 80%.

The metrics has a value of 0 when the highest SNAT port usage is under the threshold and switches to 1 when it crosses the threshold.
DropsToNATgw Packet Drops from OCI resource to NAT gateway. Packets Number of packets from OCI resources to NAT Gateway that were dropped by NAT Gateway. resourceId

dropType

ConnectionsEstablished Connections established through NAT gateway. Number Number of connections established through NAT gateway.
ConnectionsClosed Connections through NAT gateway that were closed by far ends. Number Number of connections through NAT gateway that were closed by the internet host.
ConnectionsTimedOut Connections closed by NAT gateway because of idle timeout. Number Number of connections closed by NAT gateway because of idle timeout.

Using the Console

To view default metric charts for all NAT gateways in a compartment

  1. Open the navigation menu  and select Observability & Management. Under Monitoring, select Service Metrics.
  2. Select the compartment you're interested in.
  3. Select oci_nat_gateway for the metric's Namespace.

The Service Metrics page dynamically updates the page to show charts for each metric emitted by the selected metric namespace. By default, the charts show a separate line for each resource in the compartment.