Inethiwekhi ye-EPON isebenzisa indlela ye-FTTB ukuze yakhe inethiwekhi, futhi iyunithi eyisisekelo yenethiwekhi i-OLT ne-ONU. I-OLT ihlinzeka ngamachweba amaningi we-PON wemishini yehhovisi elimaphakathi ukuxhuma imishini ye-ONU; I-ONU imishini yomsebenzisi ehlinzeka ngedatha ehambisanayo nezixhumi zezwi ukuze uthole ukufinyelela kwesevisi yomsebenzisi. Ukuze kusetshenziswe ukufinyelela kwezinsizakalo ezahlukene, abasebenzisi abahlukene kanye nezinsizakalo ezihlukene zimakwa ngamathegi ahlukene e-VLAN ukuze adluliselwe ngokusobala kuseva yokufinyelela yesevisi ehambisanayo, futhi amathegi e-VLAN ahambisanayo ayahluthulwa futhi athunyelwe kunethiwekhi yenkampani ye-IP ukuze idluliselwe.
1. Isingeniso senethiwekhi ye-EPON
I-EPON (i-Ethernet Passive Optical Network) ubuchwepheshe benethiwekhi obuvelayo bokufinyelela i-fiber. Isebenzisa isakhiwo se-point-to-multipoint, imodi yokudlulisa i-fiber optical passive, esekelwe ku-high-speed Ethernet yesikhulumi kanye ne-TDM yesigaba sesikhathi se-MAC (Media Access Control) imodi yokulawula ukufinyelela kwemidiya. , Ubuchwepheshe bokufinyelela ku-Broadband obuhlinzeka ngezinsizakalo ezihlukahlukene ezihlanganisiwe. Okubizwa ngokuthi “i-passive” kusho ukuthi i-ODN ayinazo izisetshenziswa zikagesi ezisebenzayo namandla, futhi yakhiwe ngamathuluzi asetshenziswayo anjengama-optical splitters (Splitter). Yamukela ubuchwepheshe be-PON ongqimbeni olubonakalayo, isebenzisa iphrothokholi ye-Ethernet kungqimba yesixhumanisi, futhi ibona ukufinyelela kwe-Ethernet ngokusebenzisa ukwakheka kwe-topology ye-PON. Ngakho-ke, ihlanganisa izinzuzo zobuchwepheshe be-PON nobuchwepheshe be-Ethernet: izindleko eziphansi, umkhawulokudonsa ophezulu, ukuqina okuqinile, ukuhlelwa kabusha kwesevisi okuguquguqukayo nokushesha, ukuhambisana ne-Ethernet ekhona, ukuphathwa okulula nokunye.
I-EPON ingabona ukuhlanganiswa kwezwi, idatha, ividiyo nezinsizakalo zeselula. Uhlelo lwe-EPON ikakhulukazi lwakhiwe i-OLT (itheminali yomugqa wokukhanya), i-ONU (iyunithi yenethiwekhi yokubona), i-ONT (itheminali yenethiwekhi yokubona) kanye ne-ODN (inethiwekhi yokusabalalisa okubonakalayo). ngena.
Imishini yenethiwekhi esebenzayo ihlanganisa imishini yokubeka emaphakathi yehhovisi (OLT) kanye neyunithi yenethiwekhi ye-optical (ONU). I-Optical Network Units (ONUs) ihlinzeka abasebenzisi ngesixhumi esibonakalayo phakathi kwedatha, ividiyo namanethiwekhi ocingo kanye ne-PON. Umsebenzi wasekuqaleni we-ONU ukuthola isignali yendlela yokubona bese uyiguqula ibe yifomethi edingwa ngumsebenzisi (i-Ethernet, ukusakaza kwe-IP, ucingo, i-T1/E1, njll.). Imishini ye-OLT ixhunywe kunethiwekhi eyinhloko ye-IP ngokusebenzisa imicu yokubona. Ukwethulwa kwenethiwekhi yokufinyelela optical, ukumbozwa kwayo kufinyelela ku-20km, kuqinisekisa ukuthi i-OLT ingathuthukiswa ibe yi-node yendabuko ye-metro convergence node kusukela esigabeni sokuqala sokwakhiwa kwenethiwekhi yokufinyelela optical, ngaleyo ndlela kube lula ukwakheka kwenethiwekhi yesendlalelo sokuhlangana kwenethiwekhi nokulondoloza. amandla. inani lamahhovisi okuphela. Ukwengeza, izici zomthamo omkhulu, umkhawulokudonsa ophezulu wokufinyelela, ukwethembeka okuphezulu, kanye nekhono lokusekelwa kwezinga le-QoS lezinsizakalo eziningi zenethiwekhi yokufinyelela optical nakho kwenza ukuvela kwenethiwekhi yokufinyelela ibe yinkundla yokuthwala ehlangene, ehlanganisiwe, nephumelelayo.
2. Umgomo oyisisekelo wenethiwekhi ye-EPON
Isistimu ye-EPON isebenzisa ubuchwepheshe be-WDM ukuze ibone ukudluliswa kwe-bidirectional ye-fiber eyodwa, isebenzisa i-uplink 1310nm kanye ne-downlink 1490nm wavelengths ukuze idlulise idatha nezwi, kuyilapho izinsizakalo ze-CATV zisebenzisa ubude beza beza obungu-1550nm ukuze buthwale. I-OLT ibekwe ekugcineni kwehhovisi elimaphakathi ukuze isabalalise futhi ilawule ukuxhunywa kwesiteshi, futhi inomsebenzi wesikhathi sangempela wokuqapha, wokuphatha nokunakekela. I-ONU ibekwe ohlangothini lomsebenzisi, futhi i-OLT ne-ONU zixhunywe ngemodi engu-1:16/1:32 ngenethiwekhi yokusabalalisa ebonakalayo.
Ukuze kuhlukaniswe amasignali okuya nokubuya kubasebenzisi abaningi ku-fiber efanayo, izindlela ezimbili ezilandelayo zokuphindaphinda zingasetshenziswa.
1) I-downlink data stream isebenzisa ubuchwepheshe bokusakaza. Ku-EPON, inqubo yokudluliswa kwedatha ezansi komfula isuka ku-OLT iye kuma-ONU amaningi ithunyelwa ngokusakazwa kwedatha. Idatha isakazwa phansi komfula isuka ku-OLT iye kuma-ONU amaningi ngendlela yamaphakethe anobude obuguquguqukayo. Iphakethe ngalinye lolwazi linesihloko se-EPON, esikhomba ngokukhethekile ukuthi ingabe iphakethe lolwazi lithunyelwa ku-ONU-1, ONU-2 noma ku-ONU-3. Ingase futhi ikhonjwe njengephakethe lokusakaza kuwo wonke ama-ONU noma eqenjini elithile le-ONU (amaphakethe okusakaza okuningi). Lapho idatha ifika ku-ONU, i-ONU ithola futhi ibone amaphakethe olwazi athunyelwe kuyo ngokufaniswa kwekheli, futhi ilahla amaphakethe olwazi athunyelwe kwamanye ama-ONU. Ngemva kokuba i-ONU ibhalisiwe njengesebenzayo, i-LLID ehlukile inikezwa; lapho i-OLT ithola idatha, iqhathanisa uhlu lokubhalisa lwe-LLID. Uma i-ONU ithola idatha, ithola kuphela ozimele noma ozimele abasakazayo abafana ne-LLID yayo.
2) Ukusakazwa kwedatha okukhuphukayo kusebenzisa ubuchwepheshe be-TDMA. I-OLT iqhathanisa uhlu lokubhalisa lwe-LLID ngaphambi kokuthola idatha; I-ONU ngayinye ithumela amafreyimu edatha esikhaleni sesikhathi esinikezwe ngokufana impahla yehhovisi elimaphakathi OLT; isikhathi esabiwe (ngokusebenzisa ubuchwepheshe obuhlukahlukene) sinxephezela umehluko webanga phakathi kwe-ONU ngayinye futhi sigwema ukungqubuzana ngakunye kwe-ONU phakathi.
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