I was trying to get more information on the Wiki about bridge admin mac address , it’s function and pro’s and con’s of using this setting!
Any interface, used for L3 communications (i.e. IP connections) needs MAC address in PtMP environment. Bridge in ROS is an interface as well, so it needs a MAC address. If it’s not set, then bridge interface assumes MAC address of first member port (in SOHO default that’s ether2). Which works fine in simple setups. But, in case there are some topology changes, bridge’s MAC might be forced to change, disturbing connections. To overcome such problems, it’s possible to manually set bridge’s MAC address.
The only con of setting MAC by hand is the possibility to set it to MAC which is already present in the network.