Diagnostic Tool

This diagnostic tool is used to generate test traffic which allows you to troubleshoot network issues that may results in:

  • Frequent change in path state from Good to Bad.
  • Poor application performance.
  • Higher packet loss

Most often, these problems arise due to rate limiting configured on firewall / router, incorrect bandwidth settings, low link speed, priority queue set by network provider and so on. The diagnostic tool allows you to identify the root cause of such issues and troubleshoot it.

The diagnostic tool removes the dependency on third party tools such as iPerf which has to be manually installed on the Data Center and Branch hosts. It provides more control over the type of diagnostic traffic sent, the direction in which the diagnostic traffic flows, and the path on which the diagnostic traffic flows.

The diagnostic tool allows to generate the following two types of traffic:

  • Control: Generates traffic with no QOS/scheduling applied to the packets. As a result, the packets are sent over the path selected in the UI, even if the path is not the best at the time. This traffic is used to test specific paths and helps to identify ISP related issues. You can also use this to determine the bandwidth of the selected path.
  • Data: Simulates the traffic generated from the host with SD-WAN traffic processing. Since QoS/scheduling is applied to the packets, the packets are sent over the best path available then. Traffic is sent over multiple paths if load balancing is enabled. This traffic is used to troubleshoot QoS/scheduler related issues.


To run a diagnostic test on a path, you have to start the test on the appliances at both ends of the path. Start the diagnostic test as a server on one appliance and as a client on the other appliance.

To use diagnostics tool:

  1. On both the appliances, click Configuration > System Maintenance > Diagnostics > Diagnostics Tool.

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  2. In the Tool Mode field, select Server on one appliance and select Client on the other appliance.

  3. In the Traffic Type field, select the type of diagnostic traffic, either Control or Data. Select the same traffic type on both the appliances.

  4. In the Port field, specify the TCP / UDP port number on which the diagnostic traffic is sent. Specify the same port number on both the appliances.

  5. In the Iperf field, specify IPERF command line options, if any.


    You need not specify the following IPERF command line options:

    • -c: Client mode option is added by the diagnostic tool.
    • -s: Server mode option is added by the diagnostic tool.
    • -B: Binding IPERF to specific IP/interface is done by the diagnostic tool depending on the path selected.
    • -p: Port number is provided in the diagnostics tool.
  6. Select the WAN to LAN paths on which you want to send the diagnostic traffic. Select the same path on both the appliances.

  7. Click Start on both the appliances.

Diagnostic Tool