1 Isingeniso
Ngokuthuthuka okusheshayo kobuchwepheshe bokufinyelela ku-broadband, ubuchwepheshe obuhlukahlukene obuvelayo bokufinyelela be-broadband buvele ngemva kwemvula.Ngemva kobuchwepheshe be-PON ubuchwepheshe be-DSL kanye nobuchwepheshe bekhebula, enye inkundla yokufinyelela ekahle, i-PON ingahlinzeka ngokuqondile ngezinsizakalo zokubona noma izinsizakalo ze-FTTH.I-EPON iwuhlobo olusha lobuchwepheshe benethiwekhi yokufinyelela ifayibha, kusetshenziswa amaphuzu esakhiweni samaphuzu amaningi, ukudlulisa ukukhanya okungenamthombo, ukuhlinzeka ngezinsizakalo ezihlukahlukene ze-Ethernet.Isebenzisa ama-topology e-PON ukuze isebenzise ukufinyelela kwe-Ethernet, futhi ubuchwepheshe be-PON busetshenziswa kusendlalelo esibonakalayo kungqimba olubonakalayo.Ngakho-ke, ihlanganisa izinzuzo zobuchwepheshe be-PON nobuchwepheshe be-Ethernet: izindleko eziphansi;umkhawulokudonsa ophezulu;ukuqina okunamandla, ukuhlelwa kabusha kwesevisi okuvumelana nezimo nokushesha;ukuhambisana ne-Ethernet ekhona;ukuphathwa okulula, njll. Ukuhlolwa kwe-EPON kuhluke kakhulu kumishini ye-Ethernet evamile.Lesi sihloko sigxile kubuchwepheshe bokuhlola be-EPON.
2 Isingeniso sobuchwepheshe be-EPON kanye nenselelo yokuhlola
II-EPONuhlelo luqukethe ubuningi bamayunithi enethiwekhi ye-optical, itheminali yokukhanya (OLT), kanye ne-spectra eyodwa noma ngaphezulu (bona Umfanekiso 1).Esiqondisweni se-downlink, isignali ethunyelwe i-OLT isakazwa kuwo wonke ama-ONU.Esiqondisweni se-uplink, kusetshenziswa amasu e-TDMA eziteshi eziningi, futhi ulwazi lwe-uplink lwama-ONU amaningi lwenza ulwazi lwe-TDM ku-OLT.802.3AH Lungisa ifomethi yozimele we-Ethernet, chaza kabusha ingxenye eyandulelayo, engeza izitembu zesikhathi nezihlonzi zesixhumanisi esinengqondo (LLID).I-LLID ikhomba i-ONU ngayinye yesistimu ye-PON futhi icacisa i-LLID phakathi nenqubo yokutholwa.
3 Ubuchwepheshe obubalulekile ohlelweni lwe-PON
Kusistimu ye-EPON, ibanga elibonakalayo phakathi kwe-ONU ngayinye ne-OLT endaweni yokudlulisela ulwazi ekhuphukayo alilingani.Ngokuvamile, uhlelo lwe-EPON lubeka ukuthi ibanga elide ukusuka ku-ONU ukuya ku-OLT ngu-20km, futhi ibanga elifushane kakhulu ngu-0km.Lo mehluko ebangeni udala ukubambezeleka kwehluke phakathi kuka-0 no-200 us.Uma lingekho igebe elanele lokuzihlukanisa, amasiginali asuka kuma-ONU ahlukahlukene angase afinyelele ekugcineni kokwamukela kwe-OLT ngesikhathi esifanayo, okubangele ukungqubuzana kwamasignali akhuphuka nomfula.Ukungqubuzana kungabangela inani elikhulu lamaphutha nokulahlekelwa kokuvumelanisa, njll., okuholela ekutheni isistimu ingasebenzi kahle.Usebenzisa indlela yokuhlukanisa, qala ngokukala ibanga elibonakalayo, bese ulungisa wonke ama-ONU ebangeni elinengqondo elifanayo njenge-OLT, bese usebenzisa indlela ye-TDMA ukuze ugweme ukungqubuzana.Izindlela ezihlukene ezisetshenziswayo njengamanje zifaka phakathi ukuhlukahluka kwe-spectrum, ukuphuma kwebhendi kanye nokuvulwa kwamawindi okungaphakathi kwebhendi.Isibonelo, usebenzisa indlela yokulinganisa isikali sesikhathi, qala ngokukala isikhathi sokulibaziseka kweluphu yesiginali ukusuka ku-ONU ngayinye ukuya ku-OLT, bese ufaka ukubambezeleka okukhethekile kokulinganisa kwe-Td ye-ONU ngayinye, ukuze ukubambezeleka kweluphu yawo wonke ama-ONU ngemva kokufaka i-Td ingakwazi. ukutholwa Isikhathi (okubhekiselwa kuso njengevelu yokulibaziseka kweluphu ye-equalization Tequ) siyalingana, futhi umphumela ufana nokuhambisa i-ONU ngayinye ebangeni elinengqondo elifanayo njenge-OLT, bese ithumela ifremu ngendlela efanele ngokobuchwepheshe be-TDMA ngaphandle kokungqubuzana.
I-OLT ithola ukuthi i-ONU ohlelweni lwe-PON ngezikhathi ezithile ithumela imilayezo yeSango MPCP.Ngemva kokuba i-ONU engabhalisiwe ithola umlayezo weSango, izolinda isikhathi esingahleliwe (ukugwema ukubhaliswa kanyekanye kwama-ONU amaningi), bese ithumela umlayezo Wokubhalisa ku-OLT.Ngemva kokubhalisa ngempumelelo, i-OLT yabela i-LLID ku-ONU.
Ngemva kokubhaliswa kwe-ONU ne-OLT, i-Ethernet OAM ku-ONU iqala inqubo yokutholwa bese isungula ukuxhumana ne-OLT.I-Ethernet OAM isetshenziselwa ukuthola amaphutha akude kusixhumanisi se-ONU/OLT, icuphe i-loopback yesilawuli kude, futhi ithole ikhwalithi yesixhumanisi.Nokho, i-Ethernet OAM ihlinzeka ngosekelo lwama-OAM PDU angokwezifiso, amayunithi olwazi, nemibiko yesikhathi.Abakhiqizi abaningi be-ONU/OLT basebenzisa izandiso ze-OAM ukusetha imisebenzi ekhethekile yama-ONU.Uhlelo lokusebenza olujwayelekile ukulawula umkhawulokudonsa wabasebenzisi bokugcina ngokusebenzisa imodeli yomkhawulokudonsa enwetshiwe ku-ONU.Lolu hlelo lokusebenza olungajwayelekile luwukhiye wokuhlolwa futhi luba isithiyo ekuxhumaneni phakathi kwe-ONU ne-OLT.
Uma i-OLT inethrafikhi yokuthumela i-ONU, izophatha imininingwane ye-LLID yendawo okuyiwa kuyo i-ONU kuthrafikhi.Ngenxa yezici zokusakaza ze-PON, idatha ethunyelwe yi-OLT izosakazwa kuwo wonke ama-ONU.Ikakhulukazi, isimo lapho ithrafikhi engezansi idlulisela ukusakazwa kwesevisi yevidiyo kufanele kucatshangelwe.Ngenxa yezici zokusakaza zohlelo lwe-EPON, uma umsebenzisi enza ngendlela oyifisayo uhlelo lwevidiyo, luzosakazwa kubo bonke abasebenzisi, olusebenzisa umkhawulokudonsa ongezansi womfula.I-OLT ivamise ukusekela i-IGMP Snooping.Ingakwazi ukuqapha imilayezo ye-IGMP Joyina Yesicelo futhi ithumele idatha yokusakaza okuningi kubasebenzisi abahlobene neqembu esikhundleni sokusakaza kubo bonke abasebenzisi, ngaleyo ndlela yehlise ithrafikhi.
I-ONU eyodwa kuphela engathumela ithrafikhi ngesikhathi esithile.I-ONU inolayini abaningi ababalulekile (umugqa ngamunye uhambisana nezinga le-QoS. I-ONU ithumela umlayezo Wombiko ku-OLT ukuze icele ithuba lokuthumela, echaza isimo somugqa ngamunye. I-OLT ithumela umlayezo weSango ku-ONU ukutshela i-ONU isikhathi sokuqala kokudluliswa okulandelayo ku-OLT Kumele ikwazi ukuphatha izidingo zomkhawulokudonsa wawo wonke ama-ONU, futhi kufanele inikeze kuqala igunya lokudlulisela.Ngokokubaluleka komugqa, bhalansisa izicelo zama-ONU amaningi.I-OLT kumele ibe ikwazi ukuphatha izidingo zomkhawulokudonsa wawo wonke ama-ONU futhi yabele umkhawulokudonsa okhuphukayo okhuphukayo (okungukuthi i-algorithm ye-DBA).