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An Architecture Supporting Quality-of-Service in Virtual-Output-Queued Switches
IEICE TRANSACTIONS on Communications
Publication Date: 2000/02/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (IEICE/IEEE Joint Special Issue on Recent Progress in ATM Technologies)
Category: ATM Switch and System Development
ATM, VOQ, arbitration, allocation, scheduling,
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Input buffered switches most efficiently use memory and switch bandwidth. With Virtual Output Queueing (VOQ), head-of-line blocking can be avoided, thus breaking the throughput barrier of 58.6%. In this paper a switch architecture based on VOQ is proposed, which offers deterministic and stochastic delay bounds for prioritized traffic. This is achieved by a hybrid static and dynamic arbitration scheme, which matches ports both by a precalculated schedule and realtime calculations. By using weighted dynamic arbitration algorithms 100% throughput with lowest delays under all admissible traffic can be achieved. An integrated global priority scheme allows the multiplexing of realtime and data traffic. Following the arbitration decision, a cell scheduler decides locally in the input ports upon the next connection from which a cell is forwarded. Cell scheduling based on earliest-deadline-first (EDF) is shown to perform similar to its behaviour in an output-queued switch.