:original_name: cce_10_0602.html

.. _cce_10_0602:

Cluster Overload Control
========================

Scenario
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If overload control is enabled, concurrent requests are dynamically controlled based on the resource pressure of master nodes to keep them and the cluster available.

Notes and Constraints
---------------------

The cluster version must be 1.23 or later.

Enabling Overload Control
-------------------------

**Method 1: Enabling it when creating a cluster**

When creating a cluster of v1.23 or later, you can enable overload control during the cluster creation.

**Method 2: Enabling it in an existing cluster**

#. Log in to the CCE console and go to an existing cluster whose version is v1.23 or later.
#. On the cluster information page, view the master node information. If overload control is not enabled, a message is displayed. You can click **Start Now** to enable the function.

Overload Monitoring
-------------------

**Method 1: Using the CCE console**

#. Log in to the CCE console and go to an existing cluster whose version is v1.23 or later.

#. On the cluster information page, view the master node information. The overload level metric is displayed.

   The overload levels are as follows:

   -  Circuit breaking: Rejects all external traffic.
   -  Severe overload: Rejects 75% external traffic.
   -  Moderate overload: Rejects 50% external traffic.
   -  Slight overload: Rejects 25% external traffic.
   -  Normal: Does not reject external traffic.

**Method 2: Using the AOM concole**

You can log in to the AOM console, create a dashboard, and add the metric named **vein_overload_level**.

The meanings of the monitoring metrics are as follows:

-  0: Circuit breaking: Rejects all external traffic.
-  1: Severe overload: Rejects 75% external traffic.
-  2: Moderate overload: Rejects 50% external traffic.
-  3: Slight overload: Rejects 25% external traffic.
-  4: Normal: Does not reject external traffic.