How to enable flow control on LACP interface?

[Dmitry Nevozhay]

Hi,
i stream video from my FreeNAS server to mediaplayer,
and it's recommended to enable flow control on server and switch to get rid off the freezes (short video judders during playback)...
My serv is on E3C226D2I mobo with dual gigabit ethernet, configured as LACP lagg interface.
My switch is CISCO SG200-08, and i had enabled flow control on both ports configured as LACP group.

The question is how to enable the flow control on my lagg0 interface???
I tried to add the "mediaopt flowcontrol" string in Options field (lagg0 interface settings).
But "ifconfig lagg0 " command does not show any occurencies of "flow control" :(

UPDATE: i discovered that intel i210's flow control is managed by sysctl tunables...
and by default the flow control is fully enabled (stored at /etc/sysctl.conf):
dev.igb.0.fc=3 #enable tx and rx pause frames (default)
dev.igb.0.fc=2 #enable tx (transmit) pause frames
dev.igb.0.fc=1 #enable rx (receive) pause frames
dev.igb.0.fc=0 #disable flowcontrol

I found brief review of how the flow control works:
http://virtualthreads.blogspot.ru/2006/02/beware-ethernet-flow-control.html