To provide a communication network and a transmission control method for avoiding generation of a waiting state for a useless packet and reduction of throughput even when congestion control is performed.

Each node has a buffer for temporarily storing the received packets by every one of a plurality of transmission lines for connecting nodes. When congestion is detected by a congestion detection means which monitors the number of packets stored in the buffer, the congestion detection means informs a node at the previous stage of a transmission channel number in which the congestion is generated. The node which has received congestion information suppresses or stops transmission of the packet to be transmitted to nodes at the next stage and subsequent stages via the node at the next stage to the informed transmission channel.