The Filtered Frames are the number of frames that are processed by soft path (CPU) and are not
forwarded back onto the physical network. One example when this happens is when a frame is filtered from a port, if the destination MAC is learned on a different port in the SAT.
The frames filtered is normal for an Ethernet switch because filtering is part of a switches functionality. Another function of the switch is address learning and
those address are learned on the source port of a switch ( and build the Source Address Table (SAT). Once the MAC is associated with a port in the SAT then the switch will send traffic destined to the MAC, only to the port on which that MAC is learned and filter the frame from the other ports.