Menene PON?Fasahar hanyar sadarwa ta wayar tarho na karuwa, kuma ana son zama fagen fama da hayaki ba zai taba bacewa ba.A halin yanzu, al'adar cikin gida har yanzu fasahar ADSL ce, amma ƙarin masana'antun kayan aiki da masu aiki sun mai da hankalinsu ga fasahar samun hanyar sadarwa ta gani.
Farashin Copper yana ci gaba da hauhawa, farashin kebul na ci gaba da raguwa, kuma karuwar bukatar IPTV da sabis na wasan bidiyo yana haifar da haɓakar FTTH.Kyakkyawar tsammanin maye gurbin kebul na jan karfe da kebul na coaxial mai waya ta hanyar kebul na gani, tarho, TV na USB, da kuma bayanan watsa labarai sau uku wasan ya bayyana.
Hoto 1: PON topology
PON (Passive Optical Network) cibiyar sadarwa na gani mai wucewa shine babban fasaha don gane FTTH fiber zuwa gida, yana ba da damar samun damar fiber-to-multipoint, kamar yadda aka nuna a cikin Hoto 1, shine OLT (tashar layin gani) da gefen mai amfani na gefen ofis.The ONU (Optical Network Unit) da ODN (Optical Distribution Network) an haɗa su. Gabaɗaya, hanyar haɗin yanar gizon tana ɗaukar yanayin watsa shirye-shiryen TDM kuma mai haɓakawa yana ɗaukar yanayin TDMA (Time Division Multiple Access) yanayin don samar da yanayin itace-zuwa-multipoint. .Babban haskaka PON a matsayin fasahar samun damar gani shine "m".ODN bai ƙunshi kowane na'urorin lantarki masu aiki da kayan wutar lantarki ba.Dukkanin su sun ƙunshi abubuwan da ba a iya amfani da su ba kamar masu rarrabawa, waɗanda ke da ƙarancin gudanarwa da farashin aiki.
Tarihin Ci gaban PON
Binciken fasaha na PON ya samo asali ne a cikin 1995. A cikin Oktoba 1998, ITU ta amince da tsarin fasahar PON na tushen ATM, G, wanda kungiyar FSAN (cikakken hanyar sadarwa ta hanyar sadarwa).983. Kuma aka sani da BPON (BroadbandPON).Matsakaicin shine 155Mbps kuma yana iya goyan bayan 622Mbps zaɓi.
EFMA (Ethernetin the First Mile Alliance) ya gabatar da ra'ayi na Ethernet-PON (EPON) a ƙarshen 2000 tare da adadin watsawa na 1 Gbps da haɗin haɗin haɗin gwiwa dangane da ƙaddamarwar Ethernet mai sauƙi.
Kungiyar FSAN ce ta gabatar da GPON (Gigabit-CapablePON) a watan Satumbar 2002, kuma ITU ta amince da G a cikin Maris 2003. 984. 1 da G. 984. 2 yarjejeniya.G. 984.1 An ƙayyadadden halayen tsarin shiga GPON gabaɗaya.G.984. 2 yana ƙayyadad da rarrabawar jiki mai alaƙa sublayer na ODN (Optical Distribution Network) na GPON. A watan Yuni 2004, ITU ta sake wucewa G.984. 3, wanda ke ƙayyade abubuwan da ake buƙata don Layer Convergence (TC).
Kwatanta samfuran EPON da GPON
EPON da GPON su ne manyan mambobi biyu na hanyar sadarwa ta hanyar sadarwa, kowannensu yana da nasa cancantar, yana fafatawa da juna, masu dacewa da juna da kuma koyi da juna.Wadannan suna kwatanta su ta fuskoki daban-daban:
Rate
EPON yana ba da ƙayyadaddun haɓakawa da saukar da 1.25Gbps, ta amfani da lambar layin 8b/10b, kuma ainihin ƙimar shine 1Gbps.
GPON yana goyan bayan matakan gudu da yawa kuma yana iya tallafawa haɓakawa da saukar da saurin asymmetric, 2.5Gbps ko 1.25Gbps na ƙasa, da 1.25Gbps ko 622Mbps sama.Dangane da ainihin buƙatar, an ƙaddara ƙimar haɓakawa da haɓaka ƙasa, kuma an zaɓi na'urorin gani masu dacewa don ƙara ƙimar saurin farashin na'urar gani.
Wannan ƙarshe: GPON ya fi EPON kyau.
Raba rabo
Rarraba rabo shine nawa ONUs (masu amfani) ke ɗaukar ta tashar OLT ɗaya (ofis).
Ma'auni na EPON yana bayyana rabon rabo na 1:32.
Ma'auni na GPON yana bayyana rabon rabo zuwa 1:32 mai zuwa;1:64;1:128
A gaskiya ma, fasaha na EPON tsarin zai iya cimma mafi girma rabo rabo, kamar 1:64, 1:128, EPON kula da yarjejeniya iya goyi bayan mafi ONUs.The hanya rabo ne yafi iyakance da yi bayani dalla-dalla na na gani module, da kuma babban tsaga. rabo zai sa farashin kayan aikin gani ya tashi sosai.Bugu da ƙari, asarar shigar da PON shine 15 zuwa 18 dB, kuma babban rabon rabo yana rage nisan watsawa.Yawan bandwidth raba mai amfani kuma shine farashin babban rabon rabo.
Wannan ƙarshe: GPON yana ba da zaɓi mai yawa, amma la'akarin farashi ba a bayyane yake ba.Matsakaicin nisan jiki wanda tsarin GPON zai iya tallafawa.Lokacin da rabon tsagawar gani shine 1:16, ya kamata a tallafawa matsakaicin nisan jiki na 20km.Lokacin da rabon tsagawar gani shine 1:32, ya kamata a tallafawa matsakaicin nisa ta jiki na 10km.EPON daya ne,wannan ƙarshe: daidai.
QOS(Ingantacciyar Sabis)
EPON yana ƙara MPCP 64-byte (ka'idar sarrafa ma'auni mai yawa) zuwa madaidaicin adireshin MAC na Ethernet.MPCP yana sarrafa damar zuwa P2MP point-to-multipoint topology ta hanyar saƙonni, na'urorin jihohi, da masu ƙidayar lokaci don aiwatar da rarraba bandwidth mai ƙarfi na DBA. MPCP ya haɗa da kasafi na ONU watsa lokacin ramummuka, gano atomatik da shiga ONUs, da kuma bayar da rahoton cunkoso zuwa mafi girma yadudduka don dynamically kasafta bandwidth.MPCP samar da asali goyon baya ga P2MP topology.Koyaya, ƙa'idar ba ta rarraba abubuwan fifikon sabis ba.Duk sabis ɗin suna gasa don saurin bandwidth.GPON yana da ƙarin cikakken DBA da ingantaccen damar sabis na QoS.
GPON yana raba hanyar rarraba bandwidth sabis zuwa nau'i hudu.Mafi girman fifiko shine ƙayyadaddun (Kafaffen), Tabbatarwa, Ba a Tabbace ba, da Mafi Kyawun Ƙofi.DBA ta ƙara fayyace kwantena na zirga-zirga (T-CONT) azaman sashin tsara zirga-zirgar ababen hawa, kuma kowace T-CONT ana gano ta Alloc-ID.Kowace T-CONT na iya ƙunsar ɗaya ko fiye GEMPart-IDs.T-CONT an kasu kashi biyar na ayyuka.Nau'o'in T-CONT daban-daban suna da nau'ikan rarraba bandwidth daban-daban, waɗanda zasu iya saduwa da buƙatun QoS daban-daban na gudanawar sabis daban-daban don jinkiri, jitter, da asarar fakiti.T-CONT Nau'in 1 yana da ƙayyadaddun ƙayyadaddun lokaci mai ƙayyadaddun bandwidth, daidai da ƙayyadaddun ƙayyadaddun bandwidth (Kafaffen), wanda ya dace da sabis na jinkiri, kamar sabis na murya.Nau'in 2 yana da ƙayyadaddun bandwidth amma ramin lokaci mara iyaka.Madaidaicin ingantaccen bandwidth (Assured) rabo ya dace da tsayayyen sabis na bandwidth wanda baya buƙatar babban jitter, kamar bidiyo akan ayyukan buƙatu.Nau'in 3 yana da mafi ƙarancin garantin bandwidth da raba ra'ayi mai ƙarfi na bandwidth mara amfani, kuma yana da ƙayyadaddun matsakaicin matsakaicin bandwidth, daidai da ƙayyadaddun bandwidth mara tabbacin (Ba a Tabbace ba), dacewa da sabis tare da buƙatun garantin sabis da babban fashe zirga-zirga.Irin su zazzage kasuwanci.Nau'in 4 yana da alaƙa da BestEffort, babu garantin bandwidth, dace da sabis tare da ƙarancin latency da buƙatun jitter, kamar sabis na binciken WEB.Nau'in 5 shine nau'in haɗin gwiwa, bayan rarraba garanti da bandwidth mara garanti, ƙarin Buƙatun bandwidth ana keɓance mafi kyau gwargwadon yiwuwa.
Kammalawa: GPON ya fi EPON kyau
Yi aiki da kula da OAM
EPON ba shi da la'akari da yawa ga OAM, amma kawai yana bayyana alamun kuskure na ONT, madauki da saka idanu, kuma tallafi ne na zaɓi.
GPON ya bayyana PLOAM (PhysicalLayerOAM) a Layer na jiki, kuma OMCI (ONTMmanagementandControlInterface) an bayyana shi a saman Layer don gudanar da OAM a matakai da yawa. Ana amfani da PLOAM don aiwatar da ɓoye bayanan, gano matsayi, da kuma kula da kuskure.Ana amfani da ka'idar tashar ta OMCI don gudanar da ayyukan da babban Layer ya ayyana, gami da saitin sigar aiki na ONU, nau'i da yawa na sabis na T-CONT, sigogin QoS, bayanin daidaitawar buƙatun da ƙididdigar ayyuka, da sanar da abubuwan da ke gudana ta atomatik don aiwatar da daidaitawar OLT zuwa ONT.Gudanar da gano kuskure, aiki da aminci.
Kammalawa: GPON ya fi EPON kyau
Ƙwaƙwalwar Layer na haɗin gwiwa da tallafin sabis da yawa
Kamar yadda aka nuna a cikin Hoto 2, EPON yana biye da tsarin bayanan Ethernet mai sauƙi, amma yana ƙara 64-byte MPCP yarjejeniya-zuwa-multipoint control yarjejeniya zuwa Ethernet header don aiwatar da rarraba bandwidth, bandwidth zagaye-robin, da kuma gano atomatik a cikin tsarin EPON.Ragewa da sauran aiki.Babu bincike da yawa akan tallafin sabis banda sabis ɗin bayanai (kamar ayyukan aiki tare na TDM).Yawancin masu siyar da EPON sun haɓaka wasu samfuran da ba daidai ba don magance wannan matsalar, amma ba su da kyau kuma yana da wahala a cika buƙatun QoS masu ɗaukar kaya.
Hoto 2: Kwatanta GPON da EPON ɗimbin ka'idoji
GPON ya dogara ne akan sabon tsarin haɗin kai na gaba ɗaya (TC), wanda zai iya kammala daidaitawa na manyan ayyuka daban-daban.Kamar yadda aka nuna a cikin Hoto 2, yana ma'anar rufewar ATM da kuma GFP encapsulation (General Framing Protocol).Kuna iya zaɓar duka biyun.Daya shine don encapsulation na kasuwanci.Dangane da shaharar aikace-aikacen ATM na yanzu, GPON wanda ke goyan bayan rufewar GFP kawai yana samuwa.Na'urar Lite ta samo asali, tana cire ATM daga tarin yarjejeniya don rage farashi.
GFP wata hanya ce ta hanyar haɗin kai don ayyuka da yawa, wanda ITU ta bayyana a matsayin G. 7041. An yi ƙananan gyare-gyare zuwa GFP a GPON, kuma an gabatar da PortID a shugaban GFP frame don tallafawa multi-porting multiplexing.Hakanan ana gabatar da nunin ɓangaren juzu'i (Fragment) don haɓaka ingantaccen bandwidth na tsarin.Kuma kawai yana goyan bayan yanayin sarrafa bayanai don bayanan tsawon tsayi kuma baya goyan bayan yanayin sarrafa bayanai na bayanan tubalan.GPON yana da ƙarfin ɗaukar ayyuka da yawa.GPON's TC Layer yana aiki tare da gaske, yana amfani da daidaitaccen 8 kHz (125μm) firam masu tsayi masu tsayi, waɗanda ke ba GPON damar goyan bayan ƙarshen-zuwa-ƙarshen lokaci da sauran sabis na daidaitawa, musamman don tallafawa ayyukan TDM kai tsaye, abin da ake kira NativeTDM.GPON yana da "na halitta" goyon bayan sabis na TDM.
Wannan ƙarshe: Layer na TC da ke tallafawa GPON don ayyuka da yawa ya fi MPCP na EPON ƙarfi.
Kammalawa
EPON da GPON suna da nasu amfani.GPON ya fi EPON kyau dangane da alamun aiki.Koyaya, EPON yana da fa'idar lokaci da farashi.GPON yana kamawa.Sa ido ga kasuwar samun damar buɗaɗɗen faɗaɗa a nan gaba maiyuwa ba zai zama maye gurbinsa ba, ya kamata ya zama mai dacewa.Don bandwidth, sabis da yawa, babban QoS da bukatun tsaro, da fasahar ATM a matsayin abokin ciniki na kashin baya, GPON zai fi dacewa.Ga abokan ciniki masu ƙarancin farashi, QoS da buƙatun tsaro, EPON ya zama babban abu.