Okokuqala, yeyiphi ingxaki esetyenziselwa ukusombulula i-PON?
● Ngokuvela kweenkonzo ze-bandwidth ephezulu ezifana nevidiyo efunwayo, imidlalo ye-intanethi kunye ne-IPTV, abasebenzisi bakwimfuno engxamisekileyo yokwandisa i-bandwidth yokufikelela.Iindlela ezikhoyo zokufikelela kwi-Broadband esekelwe kwi-ADSL ziya zisiba nzima ukuhlangabezana neemfuno zabasebenzisi bobubanzi obuphezulu, ezimbini- indlela yokudlulisela amandla, kunye nokhuseleko.
● Ngenxa yokuhanjiswa komgama omde, amandla anamandla okuchasana kunye nomthamo omkhulu, i-fiber optical isetyenziswe ngokubanzi kwi-backbone network.Kwiminyaka yakutshanje, ngokuhla kweendleko zesixhobo se-optical, i-fiber optical ngokuthe ngcembe ibe yinto yokuqala yokukhetha kwi-transmission medium yenethiwekhi yokufikelela.
● I-Passive Optical Network (i-PON) yindleko ephantsi kwimo yokufikelela kwifayibha kwaye inokuphuculwa kakuhle.Iya ithandwa ngakumbi ngabaqhubi be-telecom kwaye ithathwa njengesisombululo esifanelekileyo sokusombulula ingxaki "yemayile yokugqibela".
Okwesibini, ukubunjwa kwePON
I-PON inamacandelo amathathu: i-optical line termination (OLT), i-optical network unit (ONU), kunye ne-passive optical splitter (POS).
I-PON yi-asymmetric, i-point-to-multipoint (P2MP) isakhiwo.Iindima ezidlalwa yi-OLT kunye ne-ONU zahlukile.I-OLT ilingana nendima yeNkosi, kwaye i-ONU ilingana nendima yekhoboka.
Okwesithathu, iingenelo zePON:
● Ukugcina
I-P2P - Akukho micu ye-optical;I-2N i-transceiver ebonakalayo
I-P2PCurb - i-fiber e-1;I-2N+2 i-transceiver ebonakalayo;ifuna unikezelo lwamandla lwasekhaya;igcina ifayibha eninzi
I-P2MP (PON) - i-fiber ye-1;i-N+1 i-transceiver ebonakalayo;inani elikhulu lemicu ye-optical egciniweyo;inani elikhulu le-transceivers optical
● Uthembekile
Umqondiso awudluli kwisixhobo sombane esisebenzayo ngexesha lenkqubo yokuhanjiswa kwePON, ukunciphisa kakhulu indawo enokuthi ingaphumeleli;
Ukusetyenziswa kwezixhobo ze-passive zenza lula ubuchwephesha benethiwekhi, kunye nesakhiwo sothungelwano esicaba kulula ukusigcina nokulawula.
● Umgama omde
Umgama wokuhanjiswa kwe-PON yi-10 ukuya kwi-20km, eyoyisa ngokupheleleyo umda womgama phakathi kwe-Ethernet kunye neendlela zokufikelela kwi-xDSL, kwaye iphakamisa kakhulu ukuguquguquka kokuthunyelwa kweofisi yomqhubi.
● I-bandwidth ephezulu
Xa kuthelekiswa ne-xDSL, i-PON ine-bandwidth ephezulu kwaye ihlangabezana ngokupheleleyo neemfuno zeenkonzo zokusasaza kwi-intanethi ye-HDTV yexesha elizayo.
● Ukuba bhetyebhetye
Imodeli yothungelwano lwePON ayikhawulelwanga, kwaye uthungelwano lomthi kunye neenkwenkwezi zeenkwenkwezi zinokwakhiwa ngokuguquguqukayo.
I-PON ifaneleka ngokukodwa kwiimeko apho iindawo zolwazi zokufikelela kumsebenzisi zihlakazekile, kwaye i-trunk optical fiber inokwanelisa ukufikelela kwabo bonke abasebenzisi ukufikelela kumanqaku olwazi.
Okwesine, umgangatho ophambili wePON
● I-GPON - i-GigabitPON, umgangatho weprotocol we-ITUG.984, ukuphuculwa kunye nokwandiswa kwe-APON, usebenzisa ifomathi yesakhelo esiqhelekileyo ukubonelela ngenkxaso kwiinkonzo ezahlukeneyo.Umlinganiselo ophezulu yi-2.5Gbps.I-GPON ineenzuzo kwisantya esiphezulu kunye nenkxaso yeenkonzo ezininzi, kodwa iteknoloji iyinkimbinkimbi, ixabiso liphezulu, kwaye ukuvuthwa kwemveliso akuphezulu.
● EPON——Ethernetover PON, IEEE802.3ah standard protocol, ehambisa iipakethi zefomathi ye-Ethernet kwinethiwekhi ye-PON kwaye inokuxhasa i-1.25Gbps ye-symmetric rate.I-EPON isekelwe kwiteknoloji ye-Ethernet kwaye iprotocol ilula kwaye iyasebenza.Xa kuthelekiswa ne-APON, i-GPON ineenzuzo ezicacileyo ngokweendleko.
Okwesihlanu, iiteknoloji eziphambili zeEPON
● Ukuphindaphinda kwesitishi
Inkqubo ye-EPON ithatha iteknoloji ye-WDM ukuqonda ukuhanjiswa kwe-fiber enye ye-bidirectional;
Ireyithi yeshaneli yi-1.25 Gbps phezulu nasezantsi.
● Imowudi yosasazo ye-EPON ezantsi – imo yosasazo
● Imowudi yothumelo lwe-EPON uplink – imo yeTDMA
● INkqubo yoLawulo lweeNqanawa ezininzi – MPCP
Ngokungafaniyo noyilo lwe-Ethernet P2P, i-PON luyilo lweP2MP.I-ONU ikhuphisana nemithombo yetshaneli ye-uplink, kwaye indlela yokubambisana iyafuneka ukuze kugwenywe ukungqubana kwedatha ye-uplink kunye nokwaba ngokufanelekileyo izibonelelo zetshaneli.Iprotocol ye-802.3ah ichaza iprotocol yokulawula ehambelanayo, i-Multi-point MAC Control Protocol (MPCP);
I-lMPCP ichaza ubukhulu becala i-Multi-point MAC Control sublayer yokwandisa kwaye ithathe indawo ye-MAC Control sublayer echazwe yi-802.3 protocol.Isakhelo solawulo lweprotocol yeMPCP inokubaluleka okuphezulu kunesakhelo sedatha ye-MACClient.
● Imbuyekezo yokulinganisa nokulibaziseka
Ugqithiso lwe-EPON uplink lwamkela imo ye-TDMA.I-OLT imisela ixesha lokuba i-ONU ithumele idatha.Ekubeni i-ONU nganye yahlukile kwi-OLT, kuya kubakho umahluko wokulibaziseka.Ukuba akukho ndlela isebenzayo yembuyekezo yokulibaziseka, ingxabano yokuhanjiswa kwedatha ye-uplink iseza kwenzeka.
Uluhlu lwe-EPON kunye nokulibaziseka kwembuyekezo zezona teknoloji ziphambili kwi-uplink channel multiplexing.Ø Kwinkqubo yeDiscoveryProcessing, iOLT ibala ixabiso le-RTT (RoundTrip Time) ye-ONU nganye ngokulinganisa i-ONU esanda kubhaliswa.
I-OLT isebenzisa i-RTT ukulungisa ixesha logunyaziso lwe-ONU nganye.
I-OLT inokuqalisa ukusuka xa ifumana iMPCP PDU.
Ubalo lwe-RTT:
Isakhelo se-GATE siqulethe indawo ethi "timestamp" esetyenziswa yi-ONU ukuhlaziya irejista yexesha lendawo.I-OLT ingabala i-RTT ngesakhelo se-REPORT efunyenweyo ukwenza imbuyekezo yovavanyo.
● Ukwabiwa kweBhandwidth eDynamic (DBA)
Ukuthelekiswa kwexesha elimiselweyo kunye neendawo zokubeka ixesha eliguqukayo:
