Hi HoangTV,

If you decide to change the factory default values for the parameters like <sendbuf> and <MSS> then their tuning should be the result of intense tests in your typical scenario.

In any case, I expect that the value of <sendbuf> is always kept higher than that of <MSS> (even slightly, in your case i can speculate 12000).
But, please let me to repeat that you should thoroughly test the choices taken.