Patent ID: 6850522

Claim:
A packet buffer device comprising: a coupled packet queue prepared for each flow, the coupled packet queue having a plurality of leaf queues individually formed for individual copy destinations belonging to a common flow to accumulate packets as elements and sequentially transfer elements sent out from one of the leaf queues located upstream to one of the leaf queues located downstream such that packets are sequentially sent out from the copy destinations belonging to the common flow; a coupling management table having a plurality of leaf tables individually associated with and prepared for the individual leaf queues to manage elements accumulated in the coupled packet queue; and a detector configured to cause the leaf table, which is associated with the leaf queue located next to the leaf queue to be deleted toward the upstream direction to detect that the leaf queue to be deleted next toward the downstream direction is under delete operation, when the leaf queue to be deleted is performing a deleting process, wherein the detector includes delete operation identifiers for the leaf queues, respectively, the delete operation identifiers indicating that the leaf queues are under the delete operation.