isolating rb750 ports in bridge mode

Dear sir

i have a rb750 and it is in bridge mode.i want that port 2-5 communicate with the port 1 and port 1 can access port 2-5 .but port 2-5 cant communicate with each other.Please give me the solution .

In the bridge ports menu, configure ports 2 - 5 to use horizon=1
Either set no horizon value, or some different horizon value for port 1.