This article contains information about configuring the SureConnect feature of the NetScaler appliance to compensate the inadequate capacity of the backend server.

Background

You can use the SureConnect feature of the NetScaler appliance to service all incoming connections with either the requested content or a custom web page that displays information about delay in the request being serviced.

When servers are overloaded with the requests, the servers might either respond slowly or not at all. The SureConnect feature enables the NetScaler appliance to detect and compensate such conditions by ensuring that every client request gets serviced in some way, such as either a custom web page or actual content is sent to the client.

Instructions

Configure SureConnect

To configure the SureConnect feature of the NetScaler appliance to compensate the inadequate capacity of the backend server, complete the following procedure:

Note: In the following procedure, it is assumed that you already have configured the required Load Balancing VServer and services and want to enable the SureConnect functionality. Additionally, the sample custom web page for SureConnect in the procedure has the minimal content provided on the NetScaler appliance.

1. Run the following command to verify that the ​SureConnect feature is licensed on the NetScaler appliance:
   > show license

2. Run the following command to verify that the feature is enabled:
   > show feature

3. If not enabled, then run the following command to enable the feature:
   > enable feature sc

4. Run the following command to enable SureConnect on the required VServer:
   > set lb vserver <SureConnect_VServer> -sc ON

5. Run the following command to configure a SureConnect policy:
   > add sc policy SureConnect_Policy -rule ns_true -delay 10000

   The built-in expression ns_true ensures that the policy is always evaluated as true and SureConnect is triggered for a request for which the delay exceeds the threshold of 10,000 microseconds.

6. Run the following command to bind the SureConnect policy to the VServer:
   bind lb vserver <SureConnect_VServer> -policyName SureConnect_Policy

Test SureConnect Configuration

To verify the preceding configuration, you need to consider the following conditions:

• You must simulate the delay specified in with the –delay parameter of the policy.

• SureConnect is triggered for the second connection after the delay condition exists.

• You must have a connection to the monitor that determines the delay from the server.

The following is one of the easy procedures to test the SureConnect configuration you have made:

1. From a web browser, access the IP address of the VServer.

2. On the backend server, stop the HTTP daemon.

3. To ensure that a new socket is used, close and reopen the web browser.

4. Access the IP address of the VServer.
   The requests you send to the VServer trigger the SureConnect feature and display the customer web page you have created for this purpose.

5. On the backend server, restart the HTTP daemon. The server starts serving the requested web page.

Note: You must configure monitoring to ensure that the HTTP daemon can fail but monitoring still passes. If the status of the service is marked as DOWN, the SureConnect feature is not triggered.

Citrix Documentation - SureConnect