Interleaved polling with adaptive cycle time: Difference between revisions

Revision as of 02:42, 24 July 2008

Revision as of 12:42, 27 January 2009

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'''Interleaved Polling with Adaptive Cycle Time''' (IPACT) is an [[algorithm]] designed by Glen Kramer and others at the [[University of California, Davis]]. IPACT is a dynamic [[bandwidth allocation]] algorithm for use in [[Ethernet]] [[passive optical network]]s (EPONs).

IPACT uses the Gate and Report messages provided by the EPON Multi-Point Control Protocol (MPCP) to allocate [[bandwidth]] to Optical Network Units (ONUs). If the [[Fiber to the x|Optical Line Terminal]] grants bandwidth to an ONU and waits until it has received that particular ONU's transmission before granting bandwidth to another ONU, then time equivalent to a whole messaging round-trip is wasted during which the upstream may remain idle. IPACT eliminates this idle time by sending [[downstream (computer science)|downstream]] grant messages to succeeding ONUs while receiving [[transmission (telecommunications)|transmission]]s from previously granted ONUs. It accomplishes this by calculating the time at which a transmission grant allocated to a previous ONU ends.