A dual fiber system uses two separate fibers: one for transmitting (Tx) and one for receiving (Rx) signals. In DWDM implementations, each direction of communication occupies a dedicated fiber, improving the stability of the transmission. They are easier to set up and give steady communication. TX is the. Choosing between a 100G single-fiber (BiDi) and a dual-fiber optical module is a critical decision in network design, directly impacting cost, fiber resource utilization, and application suitability. So, it is bidirectional and often called BIDI.