In reply to dave_59:
Thanks Dave.
All my clock generators have same functionality. They can be started/stopped at any point of time and can be frequency changed. Sometimes based on an event I have to start/stop in between the simulation. The above solution works good if it was an agent. But all my clocks are residing inside a module. It was not built in an agent as Iam restricted from doing that for clock generation. In this case, How would I approach?