Dongosolo la EPON lili ndi mayunitsi angapo optical network (ONU), choyimira mzere wa kuwala (OLT), ndi maukonde amodzi kapena angapo (onani Chithunzi 1). Mu njira yowonjezera, chizindikiro chotumizidwa ndiOLTimawulutsidwa kwa onseONU. 8h Sinthani mawonekedwe a chimango, fotokozaninso gawo lakutsogolo, ndikuwonjezera nthawi ndi chizindikiritso chomveka (LLID)). LLID imazindikiritsa chilichonseONUmu dongosolo la PON, ndipo LLID imatchulidwa panthawi yotulukira.
(1) Kuthamanga
Mu dongosolo la EPON, mtunda wapakati pakati pa chilichonseONUndiOLTmu mtsinje uthenga kufala malangizo si wofanana. Dongosolo la EPON likunena kuti mtunda wautali kwambiri pakati pawoONUndiOLTndi 20km, ndipo mtunda waufupi kwambiri ndi 0km. Kusiyana kwa mtundaku kupangitsa kuchedwa kusiyanasiyana pakati pa 0 ndi 200 ife. Ngati palibe kusiyana kokwanira kudzipatula, zizindikiro kuchokera zosiyanasiyanaONUakhoza kufika kumapeto kwaOLTnthawi yomweyo, zomwe zingayambitse mikangano yamasigino akumtunda. Mkanganowu udzabweretsa zolakwika zambiri ndi kutayika kolumikizana, ndi zina zambiri, zomwe zimapangitsa kuti dongosololi lilephere kugwira ntchito moyenera. Pogwiritsa ntchito njira yoyambira, yesani kaye kutalika kwa mtunda, kenako sinthani zonseONUmpaka mtunda womveka womwewo mongaOLT, kenako chitani njira ya TDMA kuti mupewe mikangano. Pakalipano, njira zosiyanasiyana zomwe zimagwiritsidwa ntchito zikuphatikizapo kufalikira-kuyambira, kutuluka kunja kwa gulu ndi mu-band-kutsegula mawindo. Mwachitsanzo, njira yoyambira ma tag nthawi imagwiritsidwa ntchito kuyeza nthawi yochedwa lopu yazizindikiro kuchokera pa chilichonseONUku kuOLT, ndiyeno ikani mtengo wa Td wofananira wina uliwonseONU, kotero kuti kuchedwa kwa nthawi zonseONUmutatha kuyika Td (Kutchedwa equalization loop delay value Tequ) ndi ofanana, zotsatira zake zimakhala zofanana ndi zomwezoONUimasunthidwa kumtunda womveka womwewo mongaOLT, ndiyeno chimango chikhoza kutumizidwa molondola malinga ndi luso la TDMA popanda mkangano. .
(2) Njira yotulukira
TheOLTamapeza kutiONUmu dongosolo la PON limatumiza mauthenga a Gate MPCP nthawi ndi nthawi. Atalandira uthenga wa Gate, osalembetsaONUadzadikirira mwachisawawa (kupewa kulembetsa munthawi yomweyo angapoONU), ndiyeno tumizani uthenga wa Register kuOLT. Pambuyo kulembetsa bwino, ndiOLTamapereka LLID kwaONU.
(3) Efaneti OAM
Pambuyo paONUadalembetsa ndiOLT, Ethernet OAM paONUimayamba njira yopezera ndikukhazikitsa kulumikizana ndiOLT. Ethernet OAM imagwiritsidwa ntchito paONU/OLTmaulalo kuti mupeze zolakwika zakutali, yambitsani ma loopback akutali, ndikuwona ulalo wabwino. Komabe, Ethernet OAM imapereka chithandizo cha ma OAM PDUs, magawo azidziwitso ndi malipoti a nthawi. AmbiriONU/OLTopanga amagwiritsa ntchito zowonjezera za OAM kukhazikitsa ntchito zapadera zaONU. Ntchito yodziwika bwino ndikuwongolera bandwidth ya ogwiritsa ntchito kumapeto ndi mtundu wa bandwidth womwe ukukulitsidwa muONU. Izi sanali muyezo ntchito ndi chinsinsi mayeso ndi kukhala chopinga intercommunication pakatiONUndiOLT.
(4) Kutsika kwa mtsinje
Pamene aOLTali ndi traffic yoti atumizeONU, idzanyamula zambiri za LLID za komwe mukupitaONUmu traffic. Chifukwa cha mawonekedwe owulutsa a PON, zomwe zimatumizidwa ndi aOLTidzaulutsidwa kwa onseONU. Tiyenera kuganizira makamaka momwe magalimoto akutsikira pansi amatumizira mavidiyo. Chifukwa cha kuwulutsa kwa dongosolo la EPON, wogwiritsa ntchito akasintha makonda pulogalamu ya kanema, imawulutsidwa kwa ogwiritsa ntchito onse, omwe amadya bandwidth yotsika kwambiri.OLTnthawi zambiri imathandizira IGMP Snooping. Ikhoza kuyang'ana mauthenga a IGMP Lowani nawo ndikutumiza deta yambiri kwa ogwiritsa ntchito okhudzana ndi gululi m'malo mofalitsa kwa ogwiritsa ntchito onse, kuchepetsa kuchuluka kwa magalimoto motere.
(5) Kuthamanga kwa mtsinje
Chimodzi chokhaONUakhoza kutumiza magalimoto pa nthawi inayake. TheONUili ndi mizere yambiri yofunika kwambiri (mzere uliwonse umafanana ndi mulingo wa QoS. TheONUamatumiza Report message kwaOLTkupempha mwayi wotumiza, kufotokoza mwatsatanetsatane za mzere uliwonse. TheOLTamatumiza uthenga Gate poyankhaONU, kunena ndiONUnthawi yoyambira kufalitsa kotsatira TheOLTiyenera kuyang'anira zofunikira za bandwidth kwa onseONU, ndipo ayenera kuika patsogolo chilolezo chotumizira. Malinga ndi patsogolo pamzere ndi moyenera zopempha za angapoONU, ndiOLTiyenera kuyang'anira zofunikira za bandwidth kwa onseONU. Kugawa kwamphamvu kwa bandwidth kumtunda (ie DBA algorithm).
2.2 Malinga ndi luso la machitidwe a EPON, zovuta zoyesa zomwe EPON imakumana nazo
(1) Poganizira kukula kwa dongosolo la EPON
Ngakhale IEEE802.3ah simatanthawuza kuchuluka kwa chiwerengero mu dongosolo la EPON, chiwerengero chachikulu chothandizidwa ndi EPON chikuchokera 16 mpaka 128. IliyonseONUkujowina dongosolo la EPON kumafuna gawo la MPCP ndi gawo la OAM. Pamene masamba ambiri akulowa mu EPON, chiopsezo cha zolakwika zamakina chidzawonjezeka. Mwachitsanzo, aliyenseONUikuyenera kupezanso njira, njira yolowera ndikuyamba gawo la OAM. Choncho, nthawi yobwezeretsa dongosolo lonse idzawonjezeka ndi chiwerengero chaONU.
(2) Vuto la kulumikizana kwa zida
Zotsatirazi zimaganiziridwa makamaka pakulumikizana kwa zida:
● The dynamic bandwidth algorithm (DBA) yoperekedwa ndi opanga osiyanasiyana ndi yosiyana.
●Opanga ena amagwiritsa ntchito “Organization Specific Elements” ya OAM kuti akhazikitse makhalidwe enaake.
●Kaya kukhazikitsidwa kwa protocol ya MPCP sikungasinthe.
●Kaya njira zoyezera mtunda zopangidwa ndi opanga osiyanasiyana zimagwirizana ndi mawotchi.
(3) Zowopsa zobisika pakufalitsa ntchito zosewerera katatu mu dongosolo la EPON
Chifukwa cha mawonekedwe opatsirana a EPON, zoopsa zina zobisika zidzayambitsidwa potumiza masewero atatu:
● Kutsika kumawononga kwambiri bandwidth: Dongosolo la EPON limagwiritsa ntchito njira yotumizira mauthenga kumunsi: iliyonseONUadzalandira kuchuluka kwa magalimoto otumizidwa kwa enaONU, kuwononga bandwidth yotsika kwambiri.
●Kuchedwa kwa mtsinje ndikokulirapo: PameneONUamatumiza data kuOLT, iyenera kudikirira mwayi wotumizira womwe waperekedwa ndi aOLT. Chifukwa chake, aONUAyenera kuteteza kuchuluka kwa magalimoto akumtunda, zomwe zingayambitse kuchedwa, jitter, ndi kutayika kwa paketi.
3 ukadaulo woyeserera wa EPON
Kuyesa kwa EPON kumaphatikizapo zinthu zingapo monga kuyesa kugwirizanirana, kuyesa kwa protocol, kuyesa kachitidwe ka kachitidwe ka makina, ntchito ndi kutsimikizira ntchito. Mayeso amtundu wanthawi zonse akuwonetsedwa mu Chithunzi 2. Zogulitsa za IXIA za IxN2X zimapereka khadi loyesera la EPON, mawonekedwe oyesera a EPON, amatha kujambula ndi kusanthula ma protocol a MPCP ndi OAM, amatha kutumiza kuchuluka kwa magalimoto a EPON, kupereka pulogalamu yoyesera yokha, komanso imathandizira ogwiritsa ntchito kuyesa. Ma algorithms a DBA.
