Spirent TestCenter GUI and API
The apply function sends a test configuration to the connected chassis.
When you make changes to a BLL configuration, the changes are only written to the local memory.
Use the apply command to transmit the configuration changes to the chassis firmware. Any changes that were made since the last apply command will be submitted.
If you are running your test by executing individual test steps, then you must apply your test configuration before you execute any test steps (such as starting router communication or starting traffic).
If you call apply when your test is executing, Spirent TestCenter applies the configuration immediately, which will affect the running test in real-time.
For small incremental changes, the apply will take an insignificant amount of time; if there are many changes, the apply takes longer.
There are cases in which the framework handles the apply implicitly. In such cases, everything seems to work, even if you made changes to configuration, but you did not add the apply command to the script.
For example, some commands will automatically trigger an apply. Starting the command sequencer will also trigger an apply.
In cases where an implicit apply is performed after an explicit apply, there is little to no performance penalty (depending on how much was changed in between the applies), and you should not be concerned.
In spite of any implicit apply commands, it is important to remember, when modifying a configuration, to always call apply to submit the changes.