Yini i-PON? Ubuchwepheshe bokufinyelela ku-Broadband buyadlondlobala, futhi bumiselwe ukuba inkundla yempi lapho intuthu ingasoze yashabalala. Njengamanje, umkhakha wasekhaya usewubuchwepheshe be-ADSL, kodwa abakhiqizi bemishini abaningi ngokwengeziwe kanye nabaqhubi baphendule ukunaka kwabo kubuchwepheshe bokufinyelela kwenethiwekhi ye-optical.
Izintengo zethusi ziyaqhubeka nokukhuphuka, amanani entengo ekhebula ayaqhubeka nokwehla, futhi isidingo esikhulayo se-IPTV nezinsizakalo zegeyimu yevidiyo kuqhuba ukukhula kwe-FTTH. Ithemba elihle lokushintsha intambo yethusi nentambo ye-coaxial enentambo ngentambo yokubona, ucingo, i-cable TV, kanye nokudlala kathathu kwedatha ye-broadband.
Umfanekiso 1: I-PON topology
Inethiwekhi ye-PON (Inethiwekhi ye-Passive Optical) iwubuchwepheshe obuyinhloko bokubona i-FTTH fiber ekhaya, ihlinzeka ngokufinyelela i-point-to-multipoint fiber, njengoba kukhonjisiwe kuMdwebo 1, iwukubaOLT(itheminali yomugqa wokubona) kanye nohlangothi lomsebenzisi ohlangothini lwehhovisi. II-ONU(Optical Network Unit) kanye ne-ODN (Optical Distribution Network) kwakhiwa.Ngokujwayelekile, i-downlink isebenzisa imodi yokusakaza ye-TDM futhi i-uplink isebenzisa imodi ye-TDMA (Time Division Multiple Access) ukuze kwakheke i-topology yesihlahla esikhomba-kuya-kumaphuzu amaningi. Okugqama kakhulu kwe-PON njengobuchwepheshe bokufinyelela obubonakalayo “buyize”. I-ODN ayinazo izisetshenziswa zikagesi ezisebenzayo kanye nempahla yamandla kagesi. Zonke zakhiwe izingxenye ze-passive ezifana nezihlukanisi, ezinezindleko eziphansi zokuphatha nokusebenza.
Umlando Wokuthuthukiswa Kwe-PON
Ucwaningo lobuchwepheshe be-PON lwaqala ngo-1995. Ngo-Okthoba 1998, i-ITU yamukela izinga lobuchwepheshe be-PON elisekelwe ku-ATM, G, eligqugquzelwa inhlangano ye-FSAN (inethiwekhi yokufinyelela isevisi egcwele). 983. Eyaziwa nangokuthi i-BPON (BroadbandPON). Izinga lingu-155Mbps futhi lingasekela ngokuzikhethela i-622Mbps.
I-EFMA (i-Ethernetin the First Mile Alliance) yethula umqondo we-Ethernet-PON (EPON) ekupheleni kuka-2000 ngezinga lokudlulisela elingu-1 Gbps kanye nesendlalelo sokuxhumanisa esisekelwe ku-Ethernet encapsulation elula.
I-GPON (Gigabit-CapablePON) yahlongozwa yinhlangano ye-FSAN ngoSepthemba 2002, futhi i-ITU yamukela i-G ngoMashi 2003. 984. 1 kanye ne-G. 984. 2 isivumelwano. G. 984.1 Izimpawu eziphelele zesistimu yokufinyelela ye-GPON zicacisiwe.G. 984. 2 icacisa isendlalelo esingaphansi esihlobene nokusatshalaliswa ngokomzimba kwe-ODN (Optical Distribution Network) ye-GPON.NgoJuni 2004, i-ITU yadlula ku-G futhi. 984. 3, ecacisa izidingo zesendlalelo se-Transmission Convergence (TC).
Ukuqhathaniswa kwemikhiqizo ye-EPON ne-GPON
I-EPON ne-GPON amalungu amabili ayinhloko okufinyelela kwenethiwekhi ye-optical, ngayinye inokufaneleka kwayo, ukuncintisana, ukuphelelisana nokufunda komunye nomunye. Okulandelayo kuziqhathanisa ezicini ezihlukahlukene:
Linganisa
I-EPON ihlinzeka ngokuxhumanisa okugxilile nokwehla kwe-1.25Gbps, isebenzisa umugqa wekhodi ongu-8b/10b, futhi izinga langempela ngu-1Gbps.
I-GPON isekela amamaki esivinini amaningi futhi ingasekela izivinini ze-asymmetric ezikhuphukayo neziphansi, 2.5Gbps noma 1.25Gbps ezansi nomfula, kanye ne-1.25Gbps noma 622Mbps uplink. Ngokwesidingo sangempela, amanani e-uplink ne-downlink ayanqunywa, futhi amamojula ahambisanayo optical akhethiwe ukuze kukhuliswe isilinganiso senani lentengo yedivayisi ebonakalayo.
Lesi siphetho: I-GPON ingcono kune-EPON.
Isilinganiso sokuhlukaniswa
Isilinganiso sokuhlukaniswa ukuthi bangakiAma-ONU(abasebenzisi) baphathwa ngomunyeOLTport (ihhovisi).
Izinga le-EPON lichaza isilinganiso sokuhlukaniswa esingu-1:32.
Izinga le-GPON lichaza isilinganiso sokuhlukaniswa kokulandelayo 1:32; 1:64; 1:128
Eqinisweni, izinhlelo ze-EPON zobuchwepheshe nazo zingafinyelela izilinganiso eziphakeme zokuhlukaniswa, ezifana no-1:64, 1:128, iphrothokholi yokulawula ye-EPON ingasekela okwengeziwe.Ama-ONU.Isilinganiso somgwaqo sinqunyelwe ngokuyinhloko ukucaciswa kokusebenza kwemojula ye-optical, futhi isilinganiso esikhulu sokuhlukaniswa sizobangela ukuthi izindleko zemojula ye-optical zikhuphuke kakhulu. Ngaphezu kwalokho, ukulahlekelwa kokufaka i-PON kungu-15 kuya ku-18 dB, futhi isilinganiso esikhulu sokuhlukaniswa sinciphisa ibanga lokudlulisela. Umkhawulokudonsa wokwabelana wabasebenzisi omningi kakhulu uyizindleko zesilinganiso esikhulu sokuhlukaniswa.
Lesi siphetho: I-GPON inikeza ukukhetha okuningi, kodwa ukucatshangelwa kwezindleko akubonakali. Ubukhulu bebanga lomzimba elingasekelwa uhlelo lwe-GPON. Uma isilinganiso sokuhlukaniswa kwe-optical singu-1:16, ibanga eliphezulu lomzimba elingu-20km kufanele lisekelwe. Uma isilinganiso sokuhlukaniswa kwe-optical singu-1:32, ibanga eliphezulu lomzimba elingu-10km kufanele lisekelwe. I-EPON iyefana,lesi siphetho: kuyalingana.
I-QOS(Ikhwalithi Yesevisi)
I-EPON yengeza i-MPCP engamabhayithi angu-64(iphrothokholi yokulawula amaphuzu amaningi) kusihloko se-Ethernet sikanhlokweni we-MAC. I-MPCP ilawula ukufinyelela ku-P2MP iphuzu kuya ku-multipoint topology ngemilayezo, imishini yesifunda, nezibali-sikhathi ukuze kusetshenziswe ukwabiwa komkhawulokudonsa oguqukayo we-DBA. I-MPCP ibandakanya ukwabiwa kweI-ONUizikhala zesikhathi sokudlulisa, ukutholwa okuzenzakalelayo kanye nokujoyinaAma-ONU, kanye nokubikwa kokuminyana ezendlalelo eziphakeme ukuze kwabiwe umkhawulokudonsa.MPCP inikeza ukusekelwa okuyisisekelo kwe-topology ye-P2MP. Kodwa-ke, umthetho olandelwayo awuzihlukanisi izinto ezibalulekile zesevisi. Zonke izinsiza ziqhudelana ngokungahleliwe kumkhawulokudonsa. I-GPON ine-DBA ephelele kanye nekhono elihle kakhulu lesevisi ye-QoS.
I-GPON ihlukanisa indlela yokwabiwa komkhawulokudonsa wesevisi ibe izinhlobo ezine. Okubalulekile okuphezulu kulungisiwe (Kulungisiwe), Kuqinisekisiwe, Okungaqinisekisiwe, kanye Nomzamo Ongcono Kakhulu. I-DBA iphinde ichaze isiqukathi sethrafikhi (T-CONT) njengeyunithi yokushejula i-uplink, futhi i-T-CONT ngayinye ikhonjwa nge-Alloc-ID. I-T-CONT ngayinye ingaba ne-GEMPort-ID eyodwa noma ngaphezulu.I-T-CONT ihlukaniswe yaba izinhlobo ezinhlanu zamasevisi. Izinhlobo ezahlukene ze-T-CONTs zinezinhlobo ezahlukene zokwabiwa komkhawulokudonsa, ezingahlangabezana nezidingo ezihlukene ze-QoS zokugeleza kwesevisi okuhlukile kokulibaziseka, i-jitter, kanye nezinga lokulahlekelwa kwephakethe.Uhlobo loku-1 lwe-T-CONT lubonakala ngesikhala sesikhathi esimisiwe somkhawulokudonsa, esihambisana isabelo se-fixed-bandwidth (Fixed), esilungele izinsizakalo ezizwelayo ukubambezeleka, njengezinsizakalo zezwi. Uhlobo 2 lubonakala ngomkhawulokudonsa ogxilile kodwa i-slot yesikhathi esinqunyiwe. Isabelo somkhawulokudonsa oqinisekisiwe (Oqinisekisiwe) ohambisanayo sifanele izinsizakalo zomkhawulokudonsa ogxilile ezingadingi i-jitter ephezulu, njengezinsizakalo zevidiyo lapho kudingeka khona. Uhlobo lwesi-3 lubonakala ngesiqinisekiso esincane somkhawulokudonsa kanye nokwabelana okuguquguqukayo komkhawulokudonsa omningi, futhi linomkhawulo womkhawulokudonsa omkhulu, ohambisana nesabelo somkhawulokudonsa ongaqinisekisiwe (Ongaqinisekisiwe), ofanele izinsizakalo ezinezidingo zokuqinisekisa isevisi kanye nethrafikhi yokuqhuma okukhulu. Okufana nokudawuniloda ibhizinisi.Uhlobo lwesi-4 lubonakala nge-BestEffort, akukho siqinisekiso somkhawulokudonsa, esilungele izinsizakalo ezinezimfuneko eziphansi ze-latency kanye ne-jitter, njengesevisi ye-WEB yokuphequlula. Uhlobo lwesi-5 wuhlobo oluyinhlanganisela, ngemva kokwaba umkhawulokudonsa oqinisekisiwe nongaqinisekisiwe, owengeziwe Izidingo zomkhawulokudonsa zabiwa kahle kakhulu ngangokunokwenzeka.
Isiphetho: I-GPON ingcono kune-EPON
Sebenzisa futhi ulondoloze i-OAM
I-EPON ayinakho ukucatshangelwa okuningi kwe-OAM, kodwa ivele ichaze inkomba yephutha yerimothi ye-ONT, i-loopback nokuqapha kwesixhumanisi, futhi iwukusekela kokuzithandela.
I-GPON ichaza i-PLOAM (PhysicalLayerOAM) kusendlalelo esibonakalayo, futhi i-OMCI (ONTManagementandControlInterface) ichazwa kusendlalelo esingaphezulu ukuze yenze ukuphatha kwe-OAM kumaleveli amaningi.I-PLOAM isetshenziselwa ukusebenzisa ukubethela kwedatha, ukutholwa kwesimo, nokuqapha amaphutha. Iphrothokholi yesiteshi se-OMCI isetshenziselwa ukuphatha izinsiza ezichazwe isendlalelo esingaphezulu, okuhlanganisa isethi yepharamitha yomsebenzi weI-ONU, uhlobo nenani lensizakalo ye-T-CONT, imingcele ye-QoS, imininingwane yokucushwa kwesicelo kanye nezibalo zokusebenza, futhi yazisa ngokuzenzakalelayo imicimbi esebenzayo yohlelo ukuze kuqaliswe ukucushwaOLTku-ONT. Ukuphathwa kokuxilongwa kwephutha, ukusebenza nokuphepha.
Isiphetho: I-GPON ingcono kune-EPON
Xhuma i-encapsulation yesendlalelo nokusekelwa kwezinsizakalo eziningi
Njengoba kuboniswe kuMfanekiso 2, i-EPON ilandela ifomethi yedatha ye-Ethernet elula, kodwa yengeza iphrothokholi yokulawula iphuzu le-MPCP engu-64-byte kusihloko se-Ethernet ukuze kusetshenziswe ukwabiwa komkhawulokudonsa, umkhawulokudonsa ojikelezayo, kanye nokutholakala okuzenzakalelayo ohlelweni lwe-EPON. Ukuhamba neminye imisebenzi. Alukho ucwaningo oluningi ekusekelweni kwezinsizakalo ngaphandle kwamasevisi edatha (njengamasevisi okuvumelanisa e-TDM). Abathengisi abaningi be-EPON benze imikhiqizo engeyona ejwayelekile ukuze baxazulule le nkinga, kodwa ayilungile futhi kunzima ukuhlangabezana nezidingo ze-QoS zenkampani yenethiwekhi.
Umfanekiso 2: Ukuqhathaniswa kwezitaki zephrothokholi ye-GPON ne-EPON
I-GPON isekelwe kungqimba olusha ngokuphelele lwe-transport convergence (TC), olungaqedela ukulungiswa kwezinsizakalo ezisezingeni eliphezulu. Njengoba kukhonjisiwe kuMfanekiso 2, ichaza i-ATM encapsulation kanye ne-GFP encapsulation (iphrothokholi yozimele evamile). Ungakhetha kokubili. Enye ngeyokuhlanganisa ibhizinisi. Ngokubuka ukuthandwa kwamanje kwezicelo ze-ATM, i-GPON esekela kuphela i-GFP encapsulation iyatholakala. Idivayisi e-lite ibe khona, isusa i-ATM kusitaki sephrothokholi ukuze kwehliswe izindleko.
I-GFP iyinqubo yesendlalelo sesixhumanisi esijwayelekile sezinsizakalo eziningi, echazwa yi-ITU njenge-G. 7041.Inani elincane lokuguqulwa lenziwe ku-GFP ku-GPON, futhi i-PortID yethulwa enhlokweni yohlaka lwe-GFP ukuze isekele ukuphindaphindeka kwamachweba amaningi. Inkomba yokuhlukanisa i-Frag (Fragment) nayo yethulwa ukuze kwandiswe umkhawulokudonsa osebenzayo wohlelo. Futhi isekela kuphela imodi yokucubungula idatha yedatha yobude obuhlukahlukene futhi ayisekeli imodi yokucubungula ebonisa ngale idatha yamabhulokhi wedatha. I-GPON inamandla okuthwala izinsiza eziningi. Isendlalelo se-TC ye-GPON siyavumelana, sisebenzisa u-8 kHz ojwayelekile (125μm) amafreyimu anobude obungaguquki, avumela i-GPON ukuthi isekele isikhathi sokuphela-kuya-ekupheleni nezinye izinsizakalo ezilinganayo, ikakhulukazi zokusekela ngokuqondile izinsizakalo ze-TDM, okuthiwa i-NativeTDM. I-GPON inosekelo "lwemvelo" lwezinsizakalo ze-TDM.
Lesi siphetho: Isendlalelo se-TC esisekela i-GPON yezinsizakalo eziningi sinamandla kune-MPCP ye-EPON.
Isiphetho
I-EPON ne-GPON banezinzuzo zabo siqu. I-GPON ingcono kune-EPON ngokwezinkomba zokusebenza. Nokho, i-EPON inenzuzo yesikhathi nezindleko. I-GPON iyabamba. Ukubheka phambili emakethe yokufinyelela ye-broadband yesikhathi esizayo kungase kungabi indawo, kufanele kuhambisane. Ukuze uthole umkhawulokudonsa, izinsizakalo eziningi, i-QoS ephezulu kanye nezidingo zokuphepha, kanye nobuchwepheshe be-ATM njengekhasimende eliwumgogodla, i-GPON izofaneleka kakhulu. Kumakhasimende anokuzwela kwezindleko eziphansi, i-QoS nezidingo zokuphepha, i-EPON isiphenduke into ehamba phambili.