Managing flow control buffer

Abstract

A count of data segments is maintained. The count includes data segments in a queue and data segments in transit between a data source and the queue. A flow of data segments from the data source is controlled, based on a value of the count.

What is claimed is: 
     
         1 . A network node for a packet data network, comprising:
 a plurality of communication network interfaces configured to receive data packets from the packet data network and to transmit data packets on the packet data network;   a traffic management system coupled to the plurality of communication network interfaces, the traffic management system having a plurality of data paths, each data path comprising:   a respective first buffer;   a respective second buffer in communication with a respective processor and storing a respective queue;   at least one respective communication line in communication with the respective first buffer; and   a respective traffic management element configured:
 to maintain a respective count of data segments, the respective count including data segments in the respective queue and data segments in transit between a respective one of the plurality of communication network interfaces and the respective queue; and 
 to control a flow of data segments from the respective one of the plurality of communication network interfaces based on a value of the respective count; and 
 a switch fabric in communication with the second buffers of the traffic management system, the switch fabric being configured to selectively couple a data packets between data paths of the traffic management system. 
   
     
     
         2 . The network node of  claim 1 , wherein each data path of the plurality of data paths comprises a respective data pipeline between a respective first queue and a respective second queue; and
 the data segments in transit comprise data segments in the respective data pipeline.   
     
     
         3 . The network node of  claim 1 , wherein the respective traffic management element is configured to maintain the respective count of data segments by:
 incrementing the respective count of data segments when a data segment leaves the respective communication network interface; and   decrementing the respective count of data segments when a data segment leaves the respective queue.   
     
     
         4 . The network node of  claim 1 , wherein the respective queue has at least as many elements as a maximum number of data segments in transit. 
     
     
         5 . The network node of  claim 1 , wherein the respective queue has fewer elements than twice a maximum number of data segments in transit. 
     
     
         6 . The network node of  claim 1 , wherein each one of the plurality of communication network interfaces comprises a respective transceiver. 
     
     
         7 . The network node of  claim 6 , wherein each one of the plurality of communication network interfaces comprises a respective physical access module coupled to the respective transceiver. 
     
     
         8 . The network node of  claim 1 , wherein the traffic management element comprises a respective traffic manager module and a respective fabric access module. 
     
     
         9 . The network node of  claim 8 , wherein:
 the respective traffic manager module comprises a respective one of the first buffers, a respective one of the traffic management elements; and   the respective fabric access module comprises a respective one of the second buffers.   
     
     
         10 . The network node of  claim 8 , wherein:
 the respective traffic manager module comprises a respective one of the first buffers; and   the respective fabric access module comprises a respective one of the traffic management elements and a respective one of the second buffers.   
     
     
         11 . The network node of  claim 1 , wherein the network node comprises a router. 
     
     
         12 . The network node of  claim 1 , wherein the network node comprises a data switch. 
     
     
         13 . A network node for a packet data network, comprising:
 a plurality of communication network interfaces configured to receive data packets from the packet data network and to transmit data packets on the packet data network;   a traffic management system coupled to the plurality of communication network interfaces, the traffic management system having a plurality of data paths, each data path comprising:
 a respective first buffer; 
 a respective second buffer in communication with a respective processor and storing a respective queue; 
 at least one respective communication line in communication with the respective first buffer; and 
 a respective traffic management element configured:
 to maintain a respective count of data segments, the respective count including data segments in the respective queue and data segments in transit between a respective one of the plurality of communication network interfaces and the queue; and 
 to control a flow of data segments from the respective one of the plurality of communication network interfaces based on a value of the respective count; and 
 a framer in communication with the respective second buffer of the traffic management system. 
 
   
     
     
         14 . The network node of  claim 13 , wherein each data path of the plurality of data paths comprises a respective data pipeline between a respective first queue and a respective second queue, and the data segments in transit comprise data segments in the respective data pipeline. 
     
     
         15 . The network node of  claim 13 , wherein the respective traffic management element is configured to maintain the respective count of data segments by:
 incrementing the respective count of data segments when a data segment leaves the respective communication network interface; and   decrementing the respective count of data segments when a data segment leaves the respective queue.   
     
     
         16 . The network node of  claim 13 , wherein the respective queue has at least as many elements as a maximum number of data segments in transit. 
     
     
         17 . The network node of  claim 13 , wherein the respective queue has fewer elements than twice a maximum number of data segments in transit. 
     
     
         18 . The network node of  claim 13 , wherein each one of the plurality of communication network interfaces comprises a respective transceiver. 
     
     
         19 . The network node of  claim 18 , wherein each one of the plurality of communication network interfaces comprises a respective physical access module coupled to the respective transceiver. 
     
     
         20 . The network node of  claim 13 , wherein the respective traffic management element comprises a respective traffic manager module and a respective fabric access module. 
     
     
         21 . The network node of  claim 20 , wherein:
 the respective traffic manager module comprises a respective one of the first buffers, a respective one of the traffic management elements; and   the respective fabric access module comprises a respective one of the second buffers.   
     
     
         22 . The network node of  claim 20 , wherein:
 the respective traffic manager module comprises a respective one of the first buffers; and   the respective fabric access module comprises a respective one of the traffic management elements and a respective one of the second buffers.