Method and apparatus for reactive congestion control in an asynchronous transfer mode (ATM) network

A wide-area communication system having local reactive congestion control comprising,

• a plurality of local communication systems, each local communication system including,
• a plurality of local sources, each local source including a local modifiable issue rate unit which transmits forward information signals at different transmission rates, said issue rate unit decreasing the transmission rate in response to the presence of congestion signals and increasing the transmission rate in response to the absence of congestion signals,
• a plurality of local destinations,
• one or more local nodes forming an asynchronous transfer mode (ATM) local network connecting the sources to the destinations, each local node including,
• a forward path for transfer of information at different selectable transmission rates in a forward direction toward a destination through the network,
• a return path for returning congestion signals in a reverse direction through the network toward a source,
• congestion signal generating means for generating congestion signals in response to congestion in the local node,
• said network having a plurality of virtual channels where, for each virtual channel,
• one of said plurality of local sources is linked to one of said plurality of local destinations through said local network by linking forward paths from one or more local nodes, and wherein said issue rate unit transmits forward information signals at different transmission rates in response to congestion signals over the virtual channel,
• said one of said plurality of local destinations is linked to said one of said plurality of local sources through said network by linking return paths from said one or more nodes,
• the congestion signal generating means in one of said local nodes generates said congestion signals for the virtual channel in response to congestion in said one of said local nodes and transmits said congestion signals over said return paths, in the reverse direction without need for propagation to said one of said plurality of destinations, to said local modifiable issue rate unit in said source,
• one or more wide-area sources connected to one of said local networks,
• one or more wide-area destinations connected to another one of said local networks,
• a plurality of local network links interconnecting two or more local networks to form a wide-area network, said wide-area network having a plurality of virtual channels where, for each virtual channel, one of said plurality of wide-area sources is linked to one of said plurality of wide-area destinations through a plurality of said local networks over said local networks and said local network links.

A communication system of one or more virtual channels having reactive congestion control comprising,

• a plurality of sources, each source including a modifiable issue rate unit which transmits forward information signals at different transmission rates in response to congestion signals, said issue rate unit transmitting, for each of one or more channels, at a maximum-channel-peak-cell-rate in the absence of congestion and at a rate below the maximum-channel-peak-cell-rate for each channel experiencing congestion,
• a plurality of destinations,
• one or more nodes forming an asynchronous transfer mode (ATM) network connecting sources to destinations, each node including,
• a forward path for transfer of information in a forward direction toward a destination through the network,
• a return path for returning congestion signals in a reverse direction through the network toward a source,
• congestion signal generating means for generating congestion signals in response to congestion in the node,
• for each of one or more virtual channels in the network,
• one of said plurality of sources is linked to one of said plurality of destinations through said network by linking forward paths from one nodes, and wherein said issue rate unit transmits forward information signals at different transmission rates in response to congestion signals over the virtual channel,
• said one of said plurality of destinations is linked to said one of said plurality of sources through said network by linking return paths from said one or more nodes,
• the congestion signal generating means in one of said nodes generates said congestion signals for the virtual channel in response to congestion in said one of said nodes and transmits said congestion signals over said return paths, in the reverse direction without need for propagation to said one of said plurality of destinations, to said modifiable issue rate unit in said source.

A multiple issue rate source for use in a communication system of one or more virtual channels having reactive control where said system includes,

• one or more of said multiple issue rate sources,
• a plurality of destinations,
• one or more nodes forming an asynchronous transfer mode (ATM) network connecting sources to destinations, each node including,
• a forward path for transfer of information in a forward direction toward a destination through the network,
• a return path for returning control signals in a reverse direction through the network toward a source,
• control signal generating means for generating control signals in response to congestion in the node,
• for each of one or more virtual channels in the network,
• one of said plurality of sources is linked to one of said plurality of destinations through said network by linking forward paths from one or more nodes,
• said one of said plurality of destinations is linked to said one of said plurality of sources through said network by linking return paths from said one or more nodes,
• the control signal generating means in one of said nodes generates said control signals for the virtual channel in response to congestion in said one of said nodes and transmits said congestion signals over said return paths to said modifiable issue rate unit in said source,
• said multiple issue rate source comprising,
• a modifiable issue rate unit having means to transmit forward information signals at different transmission rates in response to said control signals, said issue rate unit having an output for transmitting, for each of one or more virtual channels, at a maximum-channel-peak-cell-rate in the absence of a control signal and at a rate below the maximum-channel-peak-cell-rate for each channel providing a control signal.