Filtering Database
To translate between two segments types, a bridge reads a frame’s destination MAC address and decides to either forward or filter. If the bridge determines that the destination node is on another segment on the network, it forwards it (retransmits)the packet to that segment. If the destination address belongs to the same segment as the source address, the bridge filters (discards) the frame. As nodes transmit data through the bridge, the bridge establishes a filtering database (also known as a forwarding table) of known MAC addresses and their locations on the network. The bridge uses its filtering database to determine whether a packet should be forwarded or filtered.