Uhlelo lwe-EPON luqukethe amayunithi enethiwekhi ye-multiple optical (ONU), itheminali yomugqa optical (OLT), kanye nenethiwekhi eyodwa noma amaningi optical (bona Umfanekiso 1).Esiqondisweni sesandiso, isignali ethunyelwe i-OLT isakazwa kuwo wonke ama-ONU.8h Lungisa ifomethi yozimele, chaza kabusha ingxenye engaphambili, bese wengeza isikhathi nokuhlonza okunengqondo (LLID)).I-LLID ikhomba i-ONU ngayinye ohlelweni lwe-PON, futhi i-LLID icaciswa phakathi nenqubo yokutholwa.
(1) Ukuhamba
Kusistimu ye-EPON, ibanga elibonakalayo phakathi kwe-ONU ngayinye ne-OLT endaweni yokudlulisela ulwazi phezulu nomfula alilingani.Uhlelo olujwayelekile lwe-EPON lubeka ukuthi ibanga elide phakathi kwe-ONU ne-OLT ngu-20km, futhi ibanga elifushane ngu-0km.Lo mehluko webanga uzodala ukubambezeleka kwehluke phakathi kuka-0 no-200 us.Uma lingekho igebe elanele lokuzihlukanisa, amasiginali avela kuma-ONU ahlukene angase afinyelele ekugcineni kokwamukela kwe-OLT ngesikhathi esifanayo, okuzodala ukungqubuzana kwamasignali akhuphuka nomfula.Ukungqubuzana kuzodala inani elikhulu lamaphutha nokulahlekelwa kokuvumelanisa, njll., okubangela isistimu ukuthi ihluleke ukusebenza ngendlela evamile.Usebenzisa indlela yokuhlukanisa, qala ngokukala ibanga elibonakalayo, bese ulungisa wonke ama-ONU ebangeni elinengqondo elifanayo njenge-OLT, bese wenza indlela ye-TDMA ukuze uzuze ukugwema ukungqubuzana.Njengamanje, izindlela ezihlukene ezisetshenziswayo zifaka ukuhlukahluka kwe-spectrum, ukuphuma ngaphandle kwebhendi kanye nokuvulwa kwamafasitela okungaphakathi kwebhendi.Isibonelo, indlela yokulinganisa ithegi yesikhathi isetshenziselwa ukulinganisa kuqala isikhathi sokulibaziseka kweluphu yesiginali ukusuka ku-ONU ngayinye kuya ku-OLT, bese ufaka inani elithile le-Td lokulibaziseka kokulinganisa ku-ONU ngayinye, ukuze isikhathi sokulibaziseka kweluphu yawo wonke ama-ONU ngemva kokufaka i-Td. ( Okubizwa nge-equalization loop delay value Tequ) ziyalingana, umphumela uyafana nokuthi i-ONU ngayinye ihanjiswa ebangeni elinengqondo elifanayo ne-OLT, bese uhlaka lungathunyelwa ngendlela efanele ngokobuchwepheshe be-TDMA ngaphandle kokungqubuzana..
(2) Inqubo yokuthola
I-OLT ithola ukuthi i-ONU ohlelweni lwe-PON ithumela imilayezo ye-Gate MPCP ngezikhathi ezithile.Lapho ithola umlayezo weSango, i-ONU engabhalisiwe izolinda isikhathi esingahleliwe (ukugwema ukubhaliswa ngesikhathi esisodwa kwama-ONU amaningi), bese ithumela umlayezo Wokubhalisa ku-OLT.Ngemva kokubhalisa ngempumelelo, i-OLT yabela i-LLID ku-ONU.
(3) I-Ethernet OAM
Ngemuva kokuthi i-ONU isibhalise ne-OLT, i-Ethernet OAM ku-ONU iqala inqubo yokutholwa bese isungula ukuxhumana ne-OLT.I-Ethernet OAM isetshenziswa kuzixhumanisi ze-ONU/OLT ukuze kutholwe amaphutha esilawuli kude, kuqalise ama-loopback akude, futhi kutholwe ikhwalithi yesixhumanisi.Nokho, i-Ethernet OAM inikeza ukwesekwa kwama-OAM PDU enziwe ngokwezifiso, 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 ngemodeli yomkhawulokudonsa yokumisa enwetshwe ku-ONU.Lolu hlelo lokusebenza olungajwayelekile luwukhiye wokuhlolwa futhi luba isithiyo ekuxhumaneni phakathi kwe-ONU ne-OLT.
(4) Ukugeleza komfula
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.Kufanele sicabangele ikakhulukazi isimo lapho ithrafikhi engaphansi komfula isakaza ukusakazwa kwesevisi yevidiyo.Ngenxa yemvelo yokusakaza yohlelo lwe-EPON, uma umsebenzisi enza ngendlela oyifisayo uhlelo lwevidiyo, luzosakazwa kubo bonke abasebenzisi, olusebenzisa umkhawulokudonsa ongezansi kakhulu.I-OLT ivamise ukusekela i-IGMP Snooping.Ingakwazi ukuhlola imilayezo ye-IGMP Joyina Yesicelo futhi ithumele idatha yokusakaza okuningi kubasebenzisi abahlobene naleli qembu esikhundleni sokusakaza kubo bonke abasebenzisi, inciphise ithrafikhi ngale ndlela.
(5) Ukugeleza komfula
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 ukuphendula i-ONU, itshela I-ONU isikhathi sokuqala kokudlulisela okulandelayo I-OLT kufanele ikwazi ukuphatha izidingo zomkhawulokudonsa wawo wonke ama-ONU, futhi kufanele ibeke phambili imvume yokudlulisela.Ngokokubaluleka komugqa futhi ibhalansise izicelo zama-ONU amaningi, i-OLT kufanele ikwazi ukuphatha izidingo zomkhawulokudonsa wawo wonke ama-ONU Ukwabiwa okunamandla komkhawulokudonsa okhuphuka nomfula (okungukuthi i-DBA algorithm).
2.2 Ngokwezici zobuchwepheshe zohlelo lwe-EPON, izinselele zokuhlola ezibhekene nohlelo lwe-EPON
(1) Kucatshangelwa isikali sohlelo lwe-EPON
Nakuba i-IEEE802.3ah ingachazi inombolo enkulu kusistimu ye-EPON, inombolo enkulu esekelwa uhlelo lwe-EPON isuka ku-16 ukuya ku-128. I-ONU ngayinye ejoyina uhlelo lwe-EPON idinga iseshini ye-MPCP kanye neseshini ye-OAM.Njengoba amasayithi amaningi ajoyina i-EPON, ingozi yamaphutha esistimu izokhula.Isibonelo, i-ONU ngayinye idinga ukuthola kabusha inqubo, inqubo yokungena ngemvume futhi iqale iseshini ye-OAM.Ngakho-ke, isikhathi sokutakula salo lonke uhlelo sizokhula ngenani lama-ONU.
(2) Inkinga yokuxhumana kwemishini
Izici ezilandelayo zicatshangelwa kakhulu ekuxhumaneni kwemishini:
●I-algorithm ye-dynamic bandwidth (DBA) ehlinzekwa abakhiqizi abahlukene ihlukile.
●Abanye abakhiqizi basebenzisa “Izinto Eziqondile Zenhlangano” ye-OAM ukuze bamise ukuziphatha okuthile.
●Ukuthi ukuthuthukiswa kwephrothokholi ye-MPCP kuyahambisana ngokuphelele yini.
● Ukuthi izindlela zokulinganisa ibanga ezithuthukiswe abakhiqizi abahlukene ziyahambisana yini nokucutshungulwa kwewashi.
(3) Izingozi ezifihliwe ekudlulisweni kwezinsizakalo zokudlala kathathu ohlelweni lwe-EPON
Ngenxa yezimpawu zokudlulisela ze-EPON, ezinye izingozi ezifihliwe zizokwethulwa lapho kuthunyelwa izinsizakalo zokudlala kathathu:
● I-downstream imosha umkhawulokudonsa omningi: Uhlelo lwe-EPON lisebenzisa imodi yokusakaza yokusakaza ezansi nomfula: i-ONU ngayinye izothola inani elikhulu lethrafikhi elithunyelwa kwamanye ama-ONU, limosha umkhawulokudonsa omningi oya phansi.
●Ukubambezeleka komfula kukhulu uma kuqhathaniswa: Uma i-ONU ithumela idatha ku-OLT, kufanele ilinde ithuba lokudlulisela elinikezwe i-OLT.Ngakho-ke, i-ONU kufanele ivikele inani elikhulu lethrafikhi ekhuphuka nomfula, okuzobangela ukubambezeleka, i-jitter, nokulahlekelwa kwephakethe.
3 Ubuchwepheshe bokuhlola be-EPON
Ukuhlolwa kwe-EPON ikakhulukazi kufaka phakathi izici ezimbalwa ezifana nokuhlola ukusebenzisana, ukuhlolwa kwephrothokholi, ukuhlolwa kokusebenza kokudluliswa kwesistimu, isevisi nokuqinisekiswa komsebenzi.I-topology yokuhlola evamile iboniswa kuMfanekiso 2. Imikhiqizo ye-IXIA ye-IxN2X inikeza ikhadi lokuhlola le-EPON elizinikele, isixhumi esibonakalayo sokuhlola se-EPON, singathwebula futhi sihlaziye izivumelwano ze-MPCP ne-OAM, ingathumela ithrafikhi ye-EPON, inikeze uhlelo lokuhlola oluzenzakalelayo, futhi ingasiza abasebenzisi ukuhlola. I-DBA algorithms.
