In some cases, a single broadcast domain is formed by combining two or more interfaces. Two ports on your pfSense router act as if they are on the same switch, except that the firewall rules are used to control the traffic between the interfaces. This can be achieved using bridging, but you need to be careful to avoid loops when employing bridging as mentioned earlier, the primary means of preventing looping on bridges is to use the STP, which is employed by managed switches and routers (including pfSense).

It should be noted that in the current version of pfSense, bridged interfaces are treated no differently than non-bridged interfaces. Therefore, firewall rules are applied to each interface that is a member of the bridge on an inbound basis. Older versions of pfSense had filtering turned off on bridges by default, and it had to be enabled to work. In the current version...