Congestion control method for a packet-switched network

A method for controlling congestion in a packet-switched network, comprising traffic sources, traffic destinations and network nodes, said method comprising:

• determining a packet queue length in a network node;
• transmitting a congestion notification back towards the source address of an incoming data packet received at said network node, if the detected packet queue length exceeds a predetermined threshold;
• and
• performing congestion control at a predetermined intermediate network node in response to receipt of said congestion notification,
• wherein said congestion notification is indicated by setting a predetermined bit in a header of said incoming data packet, and another predetermined bit of the header of said incoming data packet is used to indicate that the queue length has dropped below said predetermined threshold,
• wherein said congestion control is performed by controlling the rate of acknowledgements routed through said intermediate network node,
• wherein a window size prediction is performed in said intermediate network node, and wherein the rate of acknowledgement is controlled based on said window size prediction, and
• wherein a new acknowledgement rate is calculated at said intermediate network node based on a respective one of the following conditional relationships:
• Pnew=Pold*R1/(1+1/w)(R1<1), if said congestion indication has been received, or
• Pnew=Pold+R2*(1+1/w)*Pmax(R2<1), if a congestion relieve indication has been received;
• wherein Pmin<Pnew<Pmax, and wherein Pold denotes the acknowledgement rate before the change, Pnew denotes the acknowledgement rate after the change, Pmin denotes a minimum acknowledgement rate not larger than a round-trip time, Pmax denotes a maximum rate equal to an access link speed, and R1 and R2 denote predefined parameters and w denotes the predicted window size.

A packet-switched telecommunication network comprising:

• network nodes interconnected by transmission lines;
• user terminals acting as traffic sources which transmit data packets and as traffic destinations which receive data packets;
• congestion notification unit configured to determine a packet queue length in a network node, and to generate a congestion notification and transmitting transmit said congestion notification back towards a source address of an incoming data packet received at said network node, if the detected packet queue length exceeds a predetermined threshold;
• and
• congestion control unit configured to perform congestion control at a predetermined intermediate network node in response to the receipt of said congestion notification;
• wherein in said congestion notification unit is configured to set congestion notification in an incoming data packet generated at the network node, and is configured to set a predetermined bit in the header of said generated data packet in response to the queue length dropping below said predetermined threshold,
• wherein said congestion control unit is configured to perform congestion control by controlling the rate of acknowledgements routed through said intermediate network node, and
• wherein said congestion control unit is configured to calculate a new acknowledgement rate is at said intermediate network node based on a respective one of the following conditional relationships:
• Pnew=Pold*R1(R1<1), if said congestion indication has been received, or
• Pnew=Pold+R2*Pmax(R2<1), if a congestion relieve indication has been received;
• wherein Pmin<Pnew<Pmax, and wherein Pold denotes the acknowledgement rate before the change, Pnew denotes the acknowledgement rate after the change, Pmin denotes a minimum acknowledgement rate not larger than a round-trip time, Pmax denotes a maximum rate equal to an access link speed, and R1 and R2 denote predefined parameters.

A packet-switched telecommunication network, comprising:

• network nodes interconnected by transmission lines;
• user terminals acting as traffic sources which transmit data packets and as traffic destinations which receive data packets;
• congestion notification unit configured to determine a packet queue length in a network node, and to generate a congestion notification and to transmit said congestion notification back towards the source address of an incoming data packet received at said network node, if the detected packet queue length exceeds a predetermined threshold;
• and
• congestion control unit configured to perform congestion control at a predetermined intermediate network node in response to the receipt of said congestion notification,
• wherein said congestion control unit is configured to perform congestion control by controlling the rate of acknowledgements routed through said intermediate network node, perform a window size prediction and, control the rate of acknowledgement on based on said window size prediction and calculate a new acknowledgement rate based on a respective one of the following conditional relationships:
• Pnew=Pold*R1/(1+1/w)(R1<1), if said congestion indication has been received, or
• Pnew=Pold+R2*(1+1/w)*Pmax(R2<1), if a congestion relieve indication has been received;
• wherein Pmin<Pnew<Pmax, and wherein Pold denotes the acknowledgement rate before the change, Pnew denotes the acknowledgement rate after the change, Pmin denotes a minimum acknowledgement rate not larger than a round-trip time, Pmax denotes a maximum rate equal to an access link speed, R1 and R2 denote predefined parameters, and w denotes the predicted window size.

A method for controlling congestion in a packet-switched network, comprising traffic sources, traffic destinations and network nodes, said method comprising:

• determining a packet queue length in a network node;
• transmitting a congestion notification back towards the source address of an incoming data packet received at said network node, if the detected packet queue length exceeds a predetermined threshold;
• and
• performing congestion control at a predetermined intermediate network node in response to receipt of said congestion notification;
• wherein said congestion notification is indicated by setting a predetermined bit in a header of said incoming data packet, and another predetermined bit of the header of said incoming data packet is used to indicate that the queue length has dropped below said predetermined threshold,
• wherein said congestion control is performed by controlling the rate of acknowledgements routed through said intermediate network node,
• wherein a delay time or acceleration time of said acknowledgements is calculated at said intermediate network node in response to each arrival of said congestion notification, and
• wherein a new acknowledgement rate is calculated at said intermediate network node based on a respective one of the following conditional relationships:
• Pnew=Pold*R1(R1<1), if said congestion indication has been received, or
• Pnew=Pold+R2*Pmax(R2<1), if a congestion relieve indication has been received;
• wherein Pmin<Pnew<Pmax, and wherein Pold denotes the acknowledgement rate before the change, Pnew denotes the acknowledgement rate after the change, Pmin denotes a minimum acknowledgement rate not larger than a round-trip time, Pmax denotes a maximum rate equal to an access link speed, and R1 and R2 denote predefined parameters.

A packet-switched telecommunication network comprising:

• network nodes interconnected by transmission lines;
• user terminals acting as traffic sources which transmit data packets and as traffic destinations which receive data packets;
• congestion notification unit configured to determine a packet queue length in a network node, and to generate a congestion notification and transmit said congestion notification back towards a source address of an incoming data packet received at said network node, if the detected packet queue length exceeds a predetermined threshold;
• and
• congestion control unit configured to perform congestion control at a predetermined intermediate network node in response to the receipt of said congestion notification;
• wherein said congestion notification unit is configured to set said congestion notification in the incoming data packet generated at said network node, and is configured to set a predetermined bit in the header of said generated data packet in response to the queue length dropping below said predetermined threshold,
• wherein said congestion control unit is configured to perform congestion control by controlling the rate of acknowledgements routed through said intermediate network node,
• wherein said congestion control unit is configured to calculate a delay time or acceleration time of said acknowledgements at said intermediate network node in response to each arrival of said congestion notification, and
• wherein said congestion control unit is configured to calculate a new acknowledgement rate is at said intermediate network node based on a respective one of the following conditional relationships:
• Pnew=Pold*R1(R1<1), if said congestion indication has been received, or
• Pnew=Pold+R2*Pmax(R2<1), if a congestion relieve indication has been received;
• wherein Pmin<Pnew<Pmax, and wherein Pold denotes the acknowledgement rate before the change, Pnew denotes the acknowledgement rate after the change, Pmin denotes a minimum acknowledgement rate not larger than a round-trip time, Pmax denotes a maximum rate equal to an access link speed, and R1 and R2 denote predefined parameters.

A method for controlling congestion in a packet-switched network, comprising traffic sources, traffic destinations and network nodes, said method comprising:

• determining a packet queue length in a network node;
• transmitting a congestion notification back towards a source address of an incoming data packet received at said network node, if the detected packet queue length exceeds a predetermined threshold;
• and
• controlling a rate of acknowledgements routed through a predetermined intermediate network node to perform congestion control at the predetermined intermediate network node in response to the receipt of said congestion notification, a window size prediction being performed in said predetermined intermediate network node, and the rate of acknowledgement is controlled based on said window size prediction;
• wherein a new acknowledgement rate is calculated at said intermediate network node based on a respective one of the following conditional relationships:
• Pnew=Pold*R1/(1+1/w)(R1<1), if said congestion indication has been received, or
• Pnew=Pold+R2*(1+1/w)*Pmax(R2<1), if a congestion relieve indication has been received;
• wherein Pmin<Pnew<Pmax, and wherein Pold denotes the acknowledgement rate before the change, Pnew denotes the acknowledgement rate after the change, Pmin denotes a minimum acknowledgement rate not larger than a round-trip time, Pmax denotes a maximum rate equal to an access link speed, R1 and R2 denote predefined parameters and w denotes the predicted window size.