Flexible threshold based buffering system for use in digital communication devices

A buffering system for use at a queueing point in a digital communications device, said system comprising:

• a memory for storing messages;
• a controller connected to the memory for determining whether to store or discard messages based on predetermined discard criteria, and including means for storing messages in the memory,
• said memory being logically partitioned into plural reserved buffer spaces allocated to groups of traffic flows and a shared buffer space, wherein each said traffic group is associated with a bound on the utilization of the shared space access restriction,
• said traffic groups being further logically subdivided into one or more sub-groups, each sub-group being provisioned with a size threshold for the number of messages that the sub-group may store in the memory,
• wherein said discard criteria in respect of a given message includes the corresponding sub-group size threshold being reached and the corresponding traffic group shared space utilization bound being reached, and
• wherein the sub-group size thresholds of a given traffic group define in aggregate a logical space larger than the buffer space of the given traffic group.

A method of buffering digital messages at a queueing point in a digital communications device employing a connection-orientated protocol, the method comprising:

• logically partitioning a memory into plural reserved buffer spaces allocated to predetermined groups of traffic flows and a shared buffer space, said traffic groups being groups of virtual connections, each virtual connection group being associated with a single class of communications traffic, and each virtual connection comprising a stream of messages;
• determining whether to store or discard a given message based on predetermined discard criteria;
• and
• logically filling the reserved buffer spaces of predetermined size to a predetermined state of congestion before logically storing messages in the shared buffer space provided the given message is not discarded;
• and
• wherein connections are provisioned with a maximum connection queue depth limit and wherein said discard criteria includes the event of a given connection reaching an amount of stored messages equal to the corresponding maximum connection queue depth limit.