Congestion avoidance in high-speed network carrying bursty traffic

A communications network having multiple nodes, comprising:

• (a) a transmitter sending from a first of said nodes to a first intermediate one of said nodes a request for an allocation of bandwidth for a data transmission from said first node to a second one of said nodes via said first intermediate node and a second intermediate node;
• (b) means for comparing said request in said first intermediate node with capacity at said first intermediate node to meet said request, and for generating a modified request to reduce said allocation if necessary, said modified request being sent from said first intermediate node to said second intermediate node;
• (c) means for comparing said modified request in said second intermediate node with capacity at said second intermediate node to meed said modified request, and for generating a second modified request to reduce said allocation if necessary, said second modified request being sent back to said first node;
• (d) said transmitter sending data from said first node to said second node using the bandwidth specified in said second modified request.

A method of transmitting a quantity of digital information from a first node in a network to a destination, comprising the steps of:

• (a) transmitting from said first node a control cell containing a request for a bandwidth allocation needed for said quantity of information, a bandwidth quote equal to said bandwidth allocation, and a duration for the requested bandwidth;
• (b) receiving said control cell at an intermediate node in said network and marking down said bandwidth quote in said control cell at said intermediate node in response to the capacity of said intermediate node at a time when said quantity of information is to be transmitted, then transmitting said control cell toward said destination;
• (c) subsequently receiving at said first node a return of said control cell in which said bandwidth quote is modified downward in accordance with capacity of other nodes in said network;
• (d) transmitting from said first node to said destination said quantity of information at a bandwidth corresponding to said modified bandwidth quote.

Apparatus for transmitting a quantity of digital information from a first node in a network to a destination, comprising:

• (a) means for transmitting from said first node a control cell containing (1) a request for a bandwidth allocation needed for said quantity of information, (2) a bandwidth quote equal to said bandwidth allocation, and (3) a duration for the requested bandwidth;
• (b) means for receiving said control cell at an intermediate node in said network and modifying downward said bandwidth quote in said control cell in response to the capacity of said intermediate node at a time when said quantity of information is to be transmitted;
• (c) means for transmitting said control cell including said modified downward bandwidth quote from said intermediate node toward said destination;
• (d) means in said first node for subsequently receiving at said node a return of said control cell in which said bandwidth quote is modified downward in accordance with capacity of other nodes in said network;
• (c) and means in said first node for transmitting from said first node to said destination said quantity of information at a bandwidth corresponding to said modified downward bandwidth quote.