To provide a communication unit and a network that can cancel the occurrence of a remote end echo in an ATM-PON(Asynchronous Transfer Mode-Passive Optical Network).

The communication unit of this invention having a remote end echo canceller is configured of a delay time measurement section that measures a transmission delay time required for a transmission signal going to and coming back from a 2nd communication unit placed between the communication unit and a destination terminal, a delay section that delays the transmission signal on the basis of the transmission delay time and provides an output of the delayed signal to the remote enc echo canceller, a network information acquisition section that acquires network information denoting whether the terminal permits or inhibits the remote end echo cancellation, and a remote end echo cancellation control section that disables the remote end echo cancellation when the network information indicates the inhibition of the remote end echo cancellation or enables the remote end echo cancellation when the network information indicates the permission of the remote end echo cancellation.