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(Passive Optical Network) An optical point-to-multipoint access network. There are no optical repeaters or other active devices in a PON, hence the name "passive." PONs are designed for local loop transmission rather than long distance and serve to bring fiber closer to the customer in order to obtain higher speed. PONs began in 1995 when a group of telecom providers organized the Full Service Access Network group (see FSAN).

An optical line terminal (OLT) device resides in the telco central office or cable company head end. It generates or passes on SONET and DWDM signals via fiber to an optical network unit (ONU) in the field. The ONU provides the optical to electrical (O-E) and electrical to optical (E-O) conversion between the fiber and the copper wires that reach homes and offices in a "fiber to the curb" (FTTC) or "fiber to the neighborhood" (FTTN) scenario. When the optical line goes directly into the building for "fiber to the home" (FTTH), an optical network terminal (ONT) is used to terminate the fiber. Fiber to the home is also called "fiber to the premises" (FTTP).

APON (ATM PON) was the first passive optical network and uses ATM for transport. BPON (Broadband PON) includes APON, Ethernet and video transports. GPON (Gigabit PON), which uses the SONET GPF frame, is designed to be efficient for packets as well as TDM. BPON and GPON are the ITU-T G.983 and G.984 standards respectively. EPON is the IEEE Ethernet standard for PONs.

Passive Optical Networks
PONs provide a way to bring high-speed fiber networks closer to the customer in the local loop.

BPON     GPON     EPONITU-T    ITU-T    IEEEG.983    G.984    802.3(Mbps)            (Gbps)ClassesSupported    B,C      A,B,C   PX10/PX20**

 Downstream   155    1.25 Gbps    1.25
 Speeds       622    2.5  Gbps

 Upstream     155     155 Mbps    1.25
 Speeds       622     622 Mbps
                     1.25 Gbps
                     2.5  Gbps

   Maximum Number of ONTsBased on Class and DistanceODN CLASS    7 km    10 km    20 km

   Class A       16      13       6
   Class B       40      32      15
   Class C      101      81      39

  ** PX10 & PX20 are similar to B and C
References in periodicals archive ?
Los ejemplares fueron obtenidos en su totalidad en zonas submareales, asociados a fondos blandos, lo cual concuerda con lo reportado por otros autores que incluso relacionan estos organismos con macrofitas (Talbot & Ward 1987, Thompson 2004), lo cual en parte se confirma con los individuos encontrados en la desembocadura del Rio Apon que estuvieron en su totalidad asociados a P.
Las subcuencas de los rios que drenan al Lago de Maracaibo son: Limon (drena a la bahia El Tablazo), Apon, Palmar, Santa Ana, Catatumbo, Escalante, Chama, Motatan, Misoa, Machango, Pueblo Viejo, entre otros.
And though Macca chose his words carefully, it is believed Beckham was told that the Real players frown apon such superstar behaviour.
He reported simply that "[t]he Duke of Somerset had his head cut of apon Towre hill betwene eight and nine a cloke in the morning" (38) and neglected to mention that the people dipped their handkerchiefs in the "good Duke's" blood as souvenirs of his martyrdom.
30) Syr, he has made howyr wyth Lombardys to Brogys apon [v.
Item Spent Apon Pallme Sondays for flowres & kaakes and Nayles and Settyng vp of the pageanttes Summa xx d
Contayning the late nues last com from Malta, wyth the horrible & pytiful affaures made by the Turks apon the sayd fortressis, and the fayer victori, wuch the Christians had before saynt Elmo, the xv.
Thwaites 14 Stendnera Araceae Bishkochu virosa Prain 15 Calotropis Asclepiadaceae Apon gigantea (L.
Los aportes sedimentarios provienen principalmente del piedemonte terciario y cuaternario constituido por las formaciones Betijoque, Isnotu y Palmar, y las terrazas y conos del Pleistoceno; asi como de las diversas formaciones que atraviesa el rio Motatan, entre las que destacan: Sierra Nevada, los Torres, Mucuchachi, Cogollo, Apon, la Luna, Isnotu, Betijoque y Aluviones Cuaternarios.
Embassy in Dhaka provided a grant of $52,000 to APON for a new rehabilitation center for female drug addicts, which opened in November 2009.
The goal of this research is to define the geometries of structural elements that show evidence of positive tectonic inversion within the Maraca and Apon formations (Lower-Middle Cretaceus) in block "VIII", central part of the Maracaibo basin, Venezuela, in order to clarify the geologic architecture of the substratum.