Interleaved polling with adaptive cycle time
Encyclopedia
Interleaved Polling with Adaptive Cycle Time (IPACT) is an algorithm
designed by Glen Kramer, Biswanath Mukherjee and Gerry Pesavento
Advanced Technology Lab.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 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
grant messages to succeeding ONUs while receiving transmission
s from previously granted ONUs. It accomplishes this by calculating the time at which a transmission grant allocated to a previous ONU ends.
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
designed by Glen Kramer, Biswanath Mukherjee and Gerry Pesavento
Advanced Technology Lab.at the University of California, Davis
University of California, Davis
The University of California, Davis is a public teaching and research university established in 1905 and located in Davis, California, USA. Spanning over , the campus is the largest within the University of California system and third largest by enrollment...
. IPACT is a dynamic bandwidth allocation
Bandwidth allocation
Bandwidth allocation refers to how radio frequencies are assigned to different applications. The radio spectrum is a finite resource creating the need for an effective allocation process. In the United States, the Federal Communications Commission or FCC has the responsibility allocating the...
algorithm for use in Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
passive optical network
Passive optical network
A passive optical network is a point-to-multipoint, fiber to the premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises, typically 16-128. A PON consists of an optical line terminal at the service provider's central...
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 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
Downstream (computer science)
In a telecommunications network or computer network, downstream refers to data sent from a network service provider to a customer.Although the best voiceband modems are called 56 kbit/s modems, downstream speeds can be limited to a few tens of kilobits per second with even lower upstream speeds...
grant messages to succeeding ONUs while receiving transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
s from previously granted ONUs. It accomplishes this by calculating the time at which a transmission grant allocated to a previous ONU ends.