Tsarin EPON ya ƙunshi rukunin cibiyar sadarwa na gani da yawa (ONUTerminal layin gani (Terminal)OLT), da ɗaya ko fiye da cibiyoyin sadarwa na gani (duba Hoto 1). A cikin hanyar tsawo, siginar da aka aiko taOLTana watsawa ga kowaONU. 8h Gyara tsarin firam, sake fasalta ɓangaren gaba, kuma ƙara lokaci da ganewar ma'ana (LLID)). LLID tana gano kowaneONUa cikin tsarin PON, kuma an ƙayyade LLID yayin aikin ganowa.
(1) Ragewa
A cikin tsarin EPON, nisa ta jiki tsakanin kowaneONUda kumaOLTa cikin hanyar watsa bayanai na sama ba daidai ba ne. Tsarin EPON na gabaɗaya ya ƙayyade cewa mafi tsayin tazara tsakaninONUkumaOLTkilomita 20 ne, kuma mafi guntu nisa shine 0km. Wannan bambancin nisa zai sa jinkirin ya bambanta tsakanin mu 0 zuwa 200. Idan babu isasshen keɓewa, sigina daga daban-dabanONUna iya kaiwa ga ƙarshen karɓarOLTa lokaci guda, wanda zai haifar da rikice-rikice na sigina na sama. Rikicin zai haifar da ɗimbin kurakurai da asarar aiki tare, da sauransu, haifar da tsarin ya kasa yin aiki akai-akai. Yin amfani da hanyar jeri, da farko auna nisan jiki, sannan daidaita dukONUzuwa nisa mai ma'ana iri ɗaya daOLT, sa'an nan kuma yi hanyar TDMA don cimma nisantar rikici. A halin yanzu, kewayon hanyoyin da ake amfani da su sun haɗa da kewayon yaɗa-bakan, jeri na waje da jeri na buɗe taga. Misali, ana amfani da hanyar jeri alamar lokaci don fara auna lokacin jinkirin sigina daga kowaneONUzuwa gaOLT, sa'an nan kuma saka takamaiman jinkirin daidaita darajar Td ga kowaneONU, sabõda haka, madauki jinkirta lokaci na dukaONUbayan shigar da Td (wanda ake kira daidaita madauki darajar jinkirin Tequ) daidai suke, sakamakon yayi kama da kowaneONUan matsar da shi zuwa nisa mai ma'ana guda ɗaya daOLT, sa'an nan kuma za a iya aika firam daidai bisa ga fasahar TDMA ba tare da rikici ba. .
(2) Tsarin ganowa
TheOLTgano cewaONUa cikin tsarin PON yana aika saƙonnin Ƙofar MPCP lokaci-lokaci. Bayan samun saƙon Ƙofar, waɗanda ba a yi rajista baONUzai jira bazuwar lokaci (don guje wa rajista na lokaci ɗaya na maharaONU), sa'an nan kuma aika saƙon Rajista zuwa gaOLT. Bayan nasarar rajista, daOLTya ba da LLID gaONU.
(3) Ethernet OAM
Bayan daONUya yi rajista tare daOLT, Ethernet OAM akanONUfara aikin ganowa kuma ya kafa haɗi tare daOLT. Ana amfani da Ethernet OAM akanONU/OLThanyoyin haɗin yanar gizo don nemo kurakurai masu nisa, haifar da loopbacks na nesa, da gano ingancin hanyar haɗin gwiwa. Koyaya, Ethernet OAM yana ba da tallafi ga OAM PDUs na musamman, raka'o'in bayanai da rahotannin lokaci. Da yawaONU/OLTmasana'antun suna amfani da kari na OAM don saita ayyuka na musamman naONU. Aikace-aikace na yau da kullun shine sarrafa bandwidth na masu amfani da ƙarshen tare da ƙirar bandwidth na daidaitawa wanda aka faɗaɗa a cikinONU. Wannan aikace-aikacen da ba daidai ba shine mabuɗin gwajin kuma ya zama cikas ga hulɗar tsakaninONUkumaOLT.
(4) Magudanar ruwa
Lokacin daOLTyana da zirga-zirga don aika daONU, zai ɗauki bayanan LLID na wurin da aka nufaONUa cikin zirga-zirga. Saboda halayen watsa shirye-shiryen PON, bayanan da aka aikoOLTza a watsa ga kowa da kowaONU. Dole ne mu yi la'akari da yanayin musamman inda zirga-zirgar ababen hawa ke watsa rafukan sabis na bidiyo. Saboda yanayin watsa shirye-shirye na tsarin EPON, lokacin da mai amfani ya tsara shirin bidiyo, za a watsa shi ga duk masu amfani, wanda ke cinye bandwidth na ƙasa sosai.OLTyawanci yana goyan bayan IGMP Snooping. Yana iya snoop IGMP Join Request saƙonnin da aika multicast bayanai ga masu amfani da alaka da wannan rukuni maimakon watsa shirye-shirye ga duk masu amfani, rage zirga-zirga ta wannan hanya.
(5) Ruwan sama
Kai kadaiONUzai iya aika zirga-zirga a wani takamaiman lokaci. TheONUyana da layukan fifiko da yawa (kowane jerin gwano yayi daidai da matakin QoS. TheONUyana aika saƙon rahoto zuwa gaOLTdon neman damar aikawa, dalla-dalla yanayin kowane jerin gwano. TheOLTya aika da sakon Gate a matsayin martani gaONU, gayawaONUlokacin farawa na gaba watsa TheOLTdole ne ya iya sarrafa buƙatun bandwidth don kowaONU, kuma dole ne a ba da fifikon izinin watsawa. Dangane da fifikon jerin gwano da daidaita buƙatun da yawaONU, daOLTdole ne ya iya sarrafa buƙatun bandwidth don kowaONU. Rarraba mai ƙarfi na bandwidth na sama (watau DBA algorithm).
2.2 Dangane da halayen fasaha na tsarin EPON, ƙalubalen gwajin da tsarin EPON ya fuskanta.
(1) Yin la'akari da sikelin tsarin EPON
Ko da yake IEEE802.3ah bai ayyana matsakaicin lamba a cikin tsarin EPON ba, matsakaicin adadin da tsarin EPON ke goyan bayan shine daga 16 zuwa 128. KowanneONUshiga tsarin EPON yana buƙatar zaman MPCP da zaman OAM. Yayin da ƙarin shafuka ke shiga EPON, haɗarin kurakuran tsarin zai ƙaru. Misali, kowanneONUyana buƙatar sake gano tsari, tsarin shiga da fara zaman OAM. Sabili da haka, lokacin dawo da tsarin duka zai karu tare da adadinONU.
(2) Matsalar sadarwa ta kayan aiki
Abubuwan da ke gaba ana la'akari da su musamman don hulɗar kayan aiki:
● Ƙwararren bandwidth mai ƙarfi (DBA) wanda masana'antun daban-daban ke bayarwa ya bambanta.
●Wasu masana'antun suna amfani da OAM's “OrganizaTion Specific Elements” don saita takamaiman halaye.
●Ko cigaban tsarin MPCP ya kasance daidai.
●Ko hanyoyin auna nisa da masana'antun daban-daban suka yi daidai da sarrafa agogo.
(3) Hatsari na ɓoye a cikin watsa ayyukan wasa sau uku a cikin tsarin EPON
Saboda halayen watsawa na EPON, za a gabatar da wasu ɓoyayyun hatsarori yayin watsa ayyukan wasa sau uku:
● Ƙarƙashin ƙasa yana ɓata yawancin bandwidth: tsarin EPON yana amfani da yanayin watsa shirye-shiryen watsa shirye-shirye a cikin ƙasa: kowaneONUzai sami adadin yawan zirga-zirgar da aka aika zuwa wasuONU, ɓata yawancin bandwidth na ƙasa.
● Jinkirin da ke sama yana da girma sosai: Lokacin daONUaika bayanai zuwa gaOLT, dole ne ya jira damar watsawa da aka ware taOLT. Saboda haka, daONUdole ne ya tanadi babban adadin zirga-zirgar ababen hawa, wanda zai haifar da jinkiri, jitter, da asarar fakiti.
3 fasahar gwajin EPON
Gwajin EPON ya ƙunshi abubuwa da yawa kamar gwajin aiki tare, gwajin yarjejeniya, gwajin aikin watsa tsarin, sabis da tabbatar da aiki. An nuna ma'auni na gwajin gwajin gwaji a cikin Hoto 2. Abubuwan IxN2X na IXIA suna ba da katin gwajin EPON mai sadaukarwa, gwajin gwajin EPON, zai iya kamawa da nazarin ka'idojin MPCP da OAM, na iya aika zirga-zirgar EPON, samar da shirin gwajin atomatik, kuma zai iya taimakawa masu amfani su gwada gwajin. DBA algorithms.
