A network system comprising a first sub-network system (Sa) and a second sub-network system (Sb) respectively including a plurality of nodes connected one another in a cascade style or in a loop style to constitute a sub-network conveying a plurality of audio signals among said plurality of nodes, a first connecting node in said first sub-network system (Sa) and a second connecting node in said second sub-network system (Sb) are connected each other to constitute a connecting network (Sc) conveying a plurality of audio signals, using a plurality of transmission channels, among said first connecting node and said second connecting node, said network system further comprising: a first controller that controls transmission of the audio signals in said first sub-network system (Sa); and a second controller that controls transmission of the audio signals in said second sub-network system (Sb), wherein said network system initiates a forwarding operation of an audio signal conveyed by said sub-network in said first sub-network system (Sa) to said sub-network in said second sub-network system (Sb) through following steps a) to d): a) said first controller selects one or more audio signals among audio signals which said first connecting node can receive via said sub-network in said first sub-network system (Sa) and sets, to said first connecting node, one or more signal names identifying the selected audio signals; b) based on the signal names set to said first connecting node in said step a), said first connecting node reserves one or more transmission channels among said plurality of transmission channels of said connecting network (Sc), sends the audio signals identified by the signal names via said connecting network (Sc) using the reserved transmission channels, and notifies, to said second connecting node and said second controller, the signal names related with the reserved transmission channels; c) said second controller selects an audio signal among the audio signals identified by the signal names, notified by said first connecting node in said step b), and sets, to said second connecting node, the signal name identifying the selected audio signal; and d) based on the signal name set to said second connecting node in said step c), said second connecting node receives the audio signal in the transmission channel related with the signal name via said connecting network (Sc), and sends the received audio signal via said sub-network in said second sub-network system (Sb). a first controller that controls transmission of the audio signals in said first sub-network system (Sa); and a second controller that controls transmission of the audio signals in said second sub-network system (Sb), wherein said network system initiates a forwarding operation of an audio signal conveyed by said sub-network in said first sub-network system (Sa) to said sub-network in said second sub-network system (Sb) through following steps a) to d): a) said first controller selects one or more audio signals among audio signals which said first connecting node can receive via said sub-network in said first sub-network system (Sa) and sets, to said first connecting node, one or more signal names identifying the selected audio signals; b) based on the signal names set to said first connecting node in said step a), said first connecting node reserves one or more transmission channels among said plurality of transmission channels of said connecting network (Sc), sends the audio signals identified by the signal names via said connecting network (Sc) using the reserved transmission channels, and notifies, to said second connecting node and said second controller, the signal names related with the reserved transmission channels; c) said second controller selects an audio signal among the audio signals identified by the signal names, notified by said first connecting node in said step b), and sets, to said second connecting node, the signal name identifying the selected audio signal; and d) based on the signal name set to said second connecting node in said step c), said second connecting node receives the audio signal in the transmission channel related with the signal name via said connecting network (Sc), and sends the received audio signal via said sub-network in said second sub-network system (Sb). a) said first controller selects one or more audio signals among audio signals which said first connecting node can receive via said sub-network in said first sub-network system (Sa) and sets, to said first connecting node, one or more signal names identifying the selected audio signals; b) based on the signal names set to said first connecting node in said step a), said first connecting node reserves one or more transmission channels among said plurality of transmission channels of said connecting network (Sc), sends the audio signals identified by the signal names via said connecting network (Sc) using the reserved transmission channels, and notifies, to said second connecting node and said second controller, the signal names related with the reserved transmission channels; c) said second controller selects an audio signal among the audio signals identified by the signal names, notified by said first connecting node in said step b), and sets, to said second connecting node, the signal name identifying the selected audio signal; and d) based on the signal name set to said second connecting node in said step c), said second connecting node receives the audio signal in the transmission channel related with the signal name via said connecting network (Sc), and sends the received audio signal via said sub-network in said second sub-network system (Sb).