aki uso 2 link com discador ficam assim:

/ip route
add comment="Rota Link1" disabled=no distance=1 dst-address=0.0.0.0/0 \
gateway=link1 routing-mark=LINK1-ROUTE scope=30 target-scope=10
add comment="Rota Link2" disabled=no distance=1 dst-address=0.0.0.0/0 \
gateway=LINK2 routing-mark=LINK2-ROUTE scope=30 target-scope=10
add disabled=no distance=2 dst-address=0.0.0.0/0 gateway=LINK1 scope=30 \
target-scope=10
add comment="Rota Link2" disabled=no distance=3 dst-address=0.0.0.0/0 \
gateway=LINK2 scope=30 target-scope=10