US Patent 7693169 Transmission apparatus and frame transmission method

A line unit holds in its active table data a number that indicates which flooding setting table is to be made active. An input frame forwarding unit embeds the number in an internal frame header of a frame that is to be output. As the number is embedded before the frame is forwarded to each line unit via a backboard, the output destination for the same frame is determined by a common active flooding setting table. Thus, frame destruction or duplication is prevented.