Cообразил сам, но начались зверские тормоза....
как избавиться от этих тормозов?
kldload ng_one2many
ngctl mkpeer em1: one2many lower one
ngctl name em1:lower multi_link
ngctl mkpeer multi_link: ksocket many0 inet/dgram/udp
ngctl name multi_link:many0 link0
ngctl msg link0: bind inet/192.168.0.5:2515
ngctl msg link0: connect inet/172.16.0.4:2515
ngctl mkpeer multi_link: ksocket many1 inet/dgram/udp
ngctl name multi_link:many1 link1
ngctl msg link1: bind inet/192.168.11.55:2516
ngctl msg link1: connect inet/172.16.0.4:2516
ngctl msg multi_link: setconfig { xmitAlg=1 failAlg=1 enabledLinks=[ 1 1 ] }
ifconfig em1 up
ngctl msg em1: setpromisc 1
ngctl msg em1: setautosrc 0