Packet switched communication system

Claim 2

A packet switched communication system as claimed in Claim 1, wherein said provision for resolving scheduling conflicts comprises a relatively high priority calendar queue and a relatively low priority calendar queue; packets of said high emission rate flows are scheduled on said high priority calendar queue; and packets of said low emission rate flows are scheduled on said low priority calendar queue; whereby said scheduling conflicts are resolved by deferring to the high priority queue.

Claim 3

A packet switched communication system including a traffic shaper for granting packets of multiple flows time multiplexed, serial access during successive time slots to a shared resource of said system in substantial compliance with individual network traffic contracts for the respective flows; said traffic contracts establishing respective nominal rates and associated tolerances of specified strictness for said flows; said traffic shaper comprising a queuing mechanism (28) for organizing pending packets of active flows in respective queues, with each of said queues having an oldest pending packet at head of queue order; a scheduling mechanism (62, 63) coupled to said queuing mechanism for scheduling the oldest pending packets of the respective flows for service at times which are selected in accordance with the respective network traffic contracts for such flows; said scheduling mechanism including a relatively high priority calendar queue and a relatively low priority calendar queue; where packets of flows having relatively strict tolerances on their contractually established nominal rates are scheduled on said high priority calendar queue, and packets of flows having relatively loose tolerances on their contractually established nominal rates are scheduled on said low priority calendar queue, whereby any scheduling conflicts are resolved by deferring to said high priority queue to enforce a serialized service schedule on the packets of said active flows, while distributing delay caused by such conflict resolution to flows having relatively loose tolerances; said high priority calendar queue having a relatively fine resolution to accommodate the scheduling of packets of flows having relatively tight tolerances to a precision which is on the order of a single one of said time slots; and said low priority calendar queue having a coarser resolution to accommodate a less precise scheduling of packets of flows having a relatively loose tolerance. a transmit mechanism (65) coupled to said queuing mechanism (28) and to said scheduling mechanism (62, 63) for transferring packets of said active flows to said shared resource in accordance with said serialized service schedule, said packets being logically transformed for subsequent operation of said traffic shaper from a pending state to a serviced state upon being transferred to said shared resource.

Claim 4

A packet switched communication system as claimed in any of Claims 1 to 3, wherein said scheduling mechanism includes a virtual time stamp mechanism for scheduling said packets for service on said calendar queues.

Claim 5

A packet switched communication system as claimed in any of claims 1 to 4, wherein said packets have a uniform fixed bit length.

Claim 6

A packet switched communication system as claimed in claim 5, wherein said packets are fixed constant byte length cells for asynchronous transfer mode communications.