/interface bridge port print
Flags: X - disabled, I - inactive, D - dynamic, H - hw-offload
# INTERFACE BRIDGE HW PVID PRIORITY PATH-COST INTERNAL-PATH-COST HORIZON
0 H ether1 bridge1 yes 1 0x80 10 10 none
1 H ether3 bridge1 yes 1 0x80 10 10 none
2 H ether4 bridge1 yes 1 0x80 10 10 none
3 H ether2 bridge1 yes 1 0x80 10 10 none
/interface bridge port export
# apr/25/2018 23:32:06 by RouterOS 6.42.1
# software id = <software ID>
#
# model = RouterBOARD 750G r3
# serial number = <serial number>
/interface bridge port
add bridge=bridge1 interface=ether1
add bridge=bridge1 interface=ether3
add bridge=bridge1 interface=ether4
add bridge=bridge1 interface=ether2