Hi Сергей Борщ,
Your answer helped me!
There are still some points that are still unclear.
First point, when to pause the case for some time to let LwIP send out some data,
and when to continue the case after the pause succeeds?
Second point, I just send UDP data by calling the function udp_send(),
and I thought the LwIP would drop the extra data inside itself.
But the test result is when data coming in to the LwIP is faster than LwIP send them out,
LwIP will be stuck. It just seems that the LwIP won't drop the extra data.
So I need to drop the extra data on the application layer, but the question is how can I know which data is the extra data?