Patent ID: 6999416

Claim:
A data network node switching Protocol Data Units (PDUs) between a plurality of data ports, each PDU having a header storing header information and a payload storing at least a portion of data to be conveyed, the data network node comprising: a. a processor switching PDUs; and b. a shared memory buffer comprising: i. a reserved temporary memory storage portion for holding, while pending a preliminary inspection of the header information prior to queuing, PDUs received via an input port of the plurality of data ports; and ii. a PDU queuing memory storage portion for holding PDUs pending processing in determining at least an output port from the plurality of data ports to switch the PDU to, the PDU queuing memory storage portion further comprising a Classes-of-Service (CoS) PDU queuing portion including a plurality of reserved CoS processing Queues, each CoS processing queue holding, while pending processing. PDUs associated with a one of a plurality of classes-of service supported at the data network node in providing support for Quality-of-Service guarantees ensuring the availability of minimum memory storage resources for data flows at the data network node, whereby the arrangement reduces PDU discard instances at the data network node by enabling the discrimination of PDIJs associated with well-behaved data flows from PDUs associated with misbehaving data flows prior to queuing thereof.