How user request pass through PE, BYNET & AMP?

The PE checks the syntax of the query, check the user security rights
Then PE come up with the best optimized plan for the execution of the query
The PE passes this plan through BYNET to AMPs.
The AMPs follow the plan and retrieve the data from its DISK.
Then AMPs passes the data to PE through BYNET.
The PE then passes the data to the user.