EPON network siv txoj hauv kev FTTB los tsim ib lub network, thiab nws cov chav sib txuas yooj yim yogOLTthiabONU. CovOLTmuab ntau PON chaw nres nkoj rau cov khoom siv hauv chaw ua haujlwm txuas mus rauONUkhoom siv;ONUyog cov neeg siv khoom siv los muab cov ntaub ntawv sib xws thiab lub suab sib cuam tshuam kom paub txog cov neeg siv kev pabcuam nkag.Qhov kev nkag mus rau cov kev pabcuam sib txawv yog siv cov cim VLAN sib txawv rau cov neeg siv sib txawv thiab cov kev pabcuam sib txawv kom pob tshab xa mus rau cov kev pabcuam nkag mus rau server, thiab xa cov coj VLAN cov cim npe rau IP tus neeg nqa khoom network rau kev sib kis.
1.Introduction to EPON Network
EPON (Ethernet Passive Optical Network) yog ib qho tshiab optical fiber nkag network technology, uas siv cov qauv point-to-multipoint, passive optical fiber kis tau tus mob, raws li high-ceev Ethernet platform thiab TDM sij hawm faib MAC (MediaAccessControl) media access control mode. , Muab cov cuab yeej siv dav dav siv rau ntau yam kev pabcuam kev sib koom ua ke.Qhov hu ua "passive" txhais tau tias ODN tsis muaj cov khoom siv hluav taws xob thiab cov khoom siv hluav taws xob, thiab tag nrho cov khoom siv passive xws li optical splitters (Splitter). Nws siv PON thev naus laus zis ntawm lub cev txheej, Ethernet raws tu qauv ntawm txheej txuas, thiab siv PON topology kom ua tiav Ethernet nkag. Yog li ntawd, nws muab cov txiaj ntsig zoo ntawm PON thev naus laus zis thiab Ethernet thev naus laus zis: tus nqi qis, siab bandwidth, muaj zog scalability, hloov tau yooj yim thiab ceev cov kev pab cuam reorganization, compatibility nrog Ethernet uas twb muaj lawm, yooj yim tswj, thiab hais txog.
EPON tuaj yeem paub txog kev sib koom ua ke ntawm lub suab, cov ntaub ntawv, video, thiab cov kev pabcuam txawb. EPON system feem ntau yog tsim los ntawmOLT(optical kab davhlau ya nyob twg),ONU(optical network unit), ONT (optical network davhlau ya nyob twg) thiab ODN (optical tis network), Nws yog nyob rau hauv kev nkag tau network theem ntawm lub network thiab yog tsim nyog rau optical fiber nkag rau broadband kev pab cuam.
Cov khoom siv hauv network muaj xws li cov khoom siv hauv chaw ua haujlwm hauv nruab nrab (OLT) thiab optical network unit (ONU). Optical network unit (ONU) muab cov neeg siv nrog kev sib txuas ntawm cov ntaub ntawv, video, thiab xov tooj sib txuas thiab PON. Thawj lub luag haujlwm ntawmONUyog kom tau txais cov teeb liab kho qhov muag thiab tom qab ntawd hloov nws mus rau hauv hom ntawv uas tus neeg siv xav tau (Ethernet, IP tshaj tawm, xov tooj, T1 / E1, thiab lwm yam).OLTcov cuab yeej txuas nrog IP core network los ntawm optical fiber. Kev taw qhia txog kev siv kho qhov muag network muaj thaj tsam li ntawm 20 km, uas ua kom ntseeg tau tias cov khoom siv kho qhov muag pom tau zoo.OLTtuaj yeem hloov kho mus rau lub nroog metropolitan convergence node los ntawm thawj theem ntawm kev tsim kho qhov muag pom kev siv network, yog li ua kom yooj yim cov qauv network ntawm cov txheej txheem nkag mus rau hauv network convergence thiab txuag cov chaw ua haujlwm kawg. Tsis tas li ntawd, cov yam ntxwv ntawm kev siv kho qhov muag network lub peev xwm loj, kev siv bandwidth siab, kev ntseeg siab, thiab ntau qhov kev pabcuam QoS qib kev txhawb nqa muaj peev xwm kuj tau ua rau kev hloov pauv ntawm kev nkag mus rau hauv kev sib koom ua ke, kev sib koom ua ke, thiab ua haujlwm tau zoo ntawm lub platform.
2.Basic Principles ntawm EPON Network
EPON system siv WDM thev naus laus zis kom ua tiav ib leeg-fiber bidirectional kis tau tus mob, siv 1310nm thiab downstream 1490nm wavelengths xa cov ntaub ntawv thiab lub suab, thiab CATV cov kev pabcuam siv 1550nm wavelength los nqa.OLTyog muab tso rau hauv lub hauv paus chaw ua hauj lwm los faib thiab tswj kev sib txuas ntawm cov channel, thiab muaj kev saib xyuas, kev tswj xyuas thiab kev saib xyuas lub sijhawm. CovONUyog muab tso rau ntawm tus neeg siv sab, thiab covOLTthiab covONUtau txuas nrog 1: 16 / 1: 32 los ntawm kev faib khoom siv kho qhov muag.
Txhawm rau cais cov teeb liab los ntawm ntau tus neeg siv ntawm tib lub fiber ntau, ob txoj kev sib txuas lus hauv qab no tuaj yeem siv.
1) Cov ntaub ntawv downstream kwj tau txais kev tshaj tawm tshuab.
Nyob rau hauv EPON, cov txheej txheem ntawm downstream cov ntaub ntawv kis tau tus mob los ntawmOLTmus rau ntau yamONUsyog xa los ntawm cov ntaub ntawv tshaj tawm. Cov ntaub ntawv yog tshaj tawm downstream los ntawm lubOLTmus rau ntau yamONUsnyob rau hauv daim ntawv ntawm kev sib txawv-ntev packets.Txhua cov ntaub ntawv pob ntawv muaj ib qhoEPONpob ntawv header, uas tshwj xeeb txheeb xyuas seb cov ntaub ntawv pob ntawv raug xa mus rauONU-1,ONU-2 lubONU-3. Nws tseem tuaj yeem raug txheeb xyuas tias yog pob ntawv tshaj tawm xa mus rau txhua tusONUslos yog rau ib qho tshwj xeebONUpawg (multicast pob ntawv). Thaum cov ntaub ntawv tuaj txog ntawm lubONU, covONUtau txais thiab txheeb xyuas cov ntaub ntawv pob ntawv xa mus rau nws los ntawm qhov chaw sib txuam, thiab muab pov tseg cov ntaub ntawv pob ntawv xa mus rau lwm tusONUs. Ib qho tshwj xeeb LLID raug faib tom qabONUtau sau npe; tusOLTpiv cov npe LLID thaum tau txais cov ntaub ntawv, thiab thaum twgONUtau txais cov ntaub ntawv, nws tsuas yog tau txais thav duab lossis tshaj tawm cov thav ntawv uas phim nws tus kheej LLID.
2) Upstream cov ntaub ntawv ntws siv TDMA thev naus laus zis.
CovOLTpiv cov npe LLID ua ntej tau txais cov ntaub ntawv; txhuaONUxa cov ntaub ntawv ncej nyob rau hauv lub sij hawm slot uniformly faib los ntawm lub hauv paus chaw ua hauj lwm cov khoomOLT; lub sijhawm teem sijhawm (los ntawm kev siv thev naus laus zis) them nyiaj rau qhov sib txawv ntawm txhua qhovONUthiab zam txhuaONUKev sib tsoo ntawm.