He aha ka PON?Ke piʻi nei ka ʻenehana komo broadband, a ua lilo ia i kahua kaua kahi e pau ʻole ai ka uahi.I kēia manawa, ʻo ka ʻenehana ADSL ka mea nui o ka home, akā ʻoi aku ka nui o nā mea hana a me nā mea hana i huli i kā lākou nānā i ka ʻenehana ʻike ʻenehana.
Ke piʻi mau nei nā kumukūʻai keleawe, ke emi nei nā kumukūʻai kelepona, a ʻo ka piʻi nui ʻana o ka noi no IPTV a me nā lawelawe pāʻani wikiō ke alakaʻi nei i ka ulu ʻana o FTTH.ʻO ka manaʻo nani o ka hoʻololi ʻana i ke kaula keleawe a me ke kaula coaxial uea e ka uwea optical, ke kelepona, ke kelepona TV, a me ka pāʻani triple data broadband.
Kiʻi 1: Topology PON
ʻO ka PON (Passive Optical Network) kaʻenehanaʻenehana nui eʻike ai i ka fiber FTTH i ka home, e hāʻawi ana i ka fiber point-to-multipoint fiber, e like me ka mea i hōʻikeʻia ma ka Figure 1,ʻo ia ka OLT (ka laina laina laina) a me kaʻaoʻao mea hoʻohana o ka ʻaoʻao ʻoihana.Hoʻokumu ʻia ka ONU (Optical Network Unit) a me ka ODN (Optical Distribution Network). ʻO ka maʻamau, hoʻohana ka downlink i ka mode broadcast TDM a hoʻohana ka uplink i ke ʻano TDMA (Time Division Multiple Access) e hana i kahi topology lāʻau point-to-multipoint. .ʻO ka mea koʻikoʻi nui loa o ka PON ma ke ʻano he ʻenehana komo optical he "passive".ʻAʻole loaʻa i ka ODN kekahi mau mea uila a me nā lako uila uila.Hoʻokumu ʻia lākou āpau i nā ʻāpana passive e like me nā splitters, he haʻahaʻa haʻahaʻa a me nā kumukūʻai hana.
Moʻolelo Hoʻomohala PON
Ua hoʻomaka ka noiʻi ʻenehana PON i ka makahiki 1995. Ma ʻOkakopa 1998, ua ʻae ka ITU i ka maʻamau ʻenehana PON e pili ana i ka ATM, G, i kākoʻo ʻia e ka hui FSAN (full service access network).983. ʻIke pū ʻia ʻo BPON (BroadbandPON).ʻO 155Mbps ka helu a hiki ke kākoʻo i ka 622Mbps.
Ua hoʻolauna ʻo EFMA (Ethernetin the First Mile Alliance) i ka manaʻo o Ethernet-PON (EPON) i ka hopena o 2000 me ka wikiwiki o ka hoʻouna ʻana o 1 Gbps a me kahi papa loulou e pili ana i kahi encapsulation Ethernet maʻalahi.
Ua noi ʻia ʻo GPON (Gigabit-CapablePON) e ka hui FSAN i Kepakemapa 2002, a ua ʻae ka ITU iā G i Malaki 2003. 984. 1 a me G. 984. 2 ʻaelike.G. 984.1 Ua kuhikuhi ʻia nā hiʻohiʻona holoʻokoʻa o ka ʻōnaehana komo GPON.G.984. 2 kiko'ī i ka mahele kino pili sublayer o ka ODN (Optical Distribution Network) o GPON.I Iune 2004, ka ITU hala G hou.984. 3, e hoakaka ana i na koi no ka papa Transmission Convergence (TC).
Hoʻohālikelike i nā huahana EPON a me GPON
ʻO EPON a me GPON nā lālā nui ʻelua o ka ʻike pūnaewele optical, kēlā me kēia me kona pono ponoʻī, e hoʻokūkū ana kekahi i kekahi, e hoʻokō ana kekahi i kekahi a me ke aʻo ʻana mai kekahi i kekahi.Hoʻohālikelike kēia mau mea iā lākou ma nā ʻano like ʻole:
Laki
Hāʻawi ʻo EPON i ka uplink paʻa a me ka downlink o 1.25Gbps, me ka hoʻohana ʻana i ka laina laina 8b/10b, a ʻo ka helu maoli ʻo 1Gbps.
Kākoʻo ʻo GPON i nā māka wikiwiki a hiki ke kākoʻo i ka uplink a me ka downlink asymmetric speeds, 2.5Gbps a i ʻole 1.25Gbps i lalo, a me 1.25Gbps a i ʻole 622Mbps uplink.E like me ka koi maoli, ua hoʻoholo ʻia ka uplink a me ka downlink rate, a ua koho ʻia nā modula optical kūpono e hoʻonui i ka lākiō kumukūʻai wikiwiki.
ʻO kēia hopena: ʻoi aku ka maikaʻi o GPON ma mua o EPON.
Lakiō māhele
ʻO ka ratio māhele ʻo ia ka nui o nā ONU (mea hoʻohana) i lawe ʻia e hoʻokahi awa OLT (keʻena).
Hōʻike ka maʻamau EPON i ka māhele māhele o 1:32.
ʻO ka maʻamau GPON ka wehewehe ʻana i ka māhele māhele i kēia 1:32;1:64;1:128
ʻO ka ʻoiaʻiʻo, hiki i nā ʻōnaehana EPON ʻenehana ke hoʻokō i nā lakio māhele kiʻekiʻe, e like me 1:64, 1:128, hiki ke kākoʻo i ka protocol control EPON i nā ONU. e piʻi nui ke kumukūʻai o ka module optical.Eia kekahi, ʻo ka PON insertion loss he 15 a 18 dB, a ʻo ka māhele māhele nui e hōʻemi i ka mamao o ka lawe ʻana.ʻO ka nui o nā mea hoʻohana kaʻana like ʻana i ka bandwidth ʻo ia hoʻi ke kumukūʻai o ka lakio māhele nui.
ʻO kēia hopena: Hāʻawi ʻo GPON i nā koho he nui, akā ʻaʻole maopopo ke kumukūʻai.ʻO ka mamao kino kiʻekiʻe loa i hiki i ka ʻōnaehana GPON ke kākoʻo.Inā ʻo 1:16 ka lākiō hoʻokaʻawale optical, pono e kākoʻo ʻia ka mamao kino kiʻekiʻe o 20km.Inā he 1:32 ka lakene opipika, pono ke kāko'o 'ia ka mamao kino o 10km.Ua like ka EPON,keia hopena: like.
QOS (Ka maikaʻi o ka lawelawe)
Hoʻohui ʻo EPON i kahi MPCP 64-byte (multi point control protocol) i ke poʻo MAC poʻomanaʻo Ethernet poʻomanaʻo. Mālama ʻo MPCP i ke komo ʻana i ka topology P2MP point-to-multipoint ma o nā memo, nā mīkini mokuʻāina, a me nā manawa e hoʻokō i ka DBA dynamic bandwidth allocation. ka hoʻokaʻawale ʻana i nā kau manawa hoʻouna ONU, ʻike ʻakomi a me ka hui ʻana o nā ONU, a me ka hōʻike ʻana i ka ʻāʻī i nā papa kiʻekiʻe e hoʻokaʻawale i ka bandwidth.MPCP ke kākoʻo kumu no ka topology P2MP.Eia naʻe, ʻaʻole hoʻokaʻawale ka protocol i nā mea nui o ka lawelawe.ʻO nā lawelawe āpau e hoʻokūkū maʻamau no ka bandwidth.Loaʻa iā GPON kahi DBA piha a me nā mana lawelawe QoS maikaʻi loa.
Hoʻokaʻawale ʻo GPON i ke ala hoʻokaʻawale bandwidth lawelawe i ʻehā ʻano.Hoʻopaʻa ʻia ka mea kiʻekiʻe loa (Fixed), Assured, Non-Assured, a me BestEffort.Ho'ākāka hou ka DBA i kahi pahu kaʻa (T-CONT) ma ke ʻano he uplink traffic scheduling unit, a ʻike ʻia kēlā me kēia T-CONT e kahi Alloc-ID.Hiki i kēlā me kēia T-CONT ke komo i hoʻokahi a ʻoi aku paha GEMPort-IDs. Ua māhele ʻia ʻo T-CONT i ʻelima ʻano lawelawe.Loaʻa nā ʻano like ʻole o T-CONT i nā ʻano hoʻokaʻawale bandwidth, hiki ke hoʻokō i nā koi QoS like ʻole o nā kahe lawelawe ʻokoʻa no ka lohi, jitter, a me ka helu o ka packet loss. kahi hoʻokaʻawale paʻa-bandwidth (Paʻa), kūpono no nā lawelawe hoʻopaneʻe, e like me nā lawelawe leo.Hōʻike ʻia ka ʻano 2 e kahi bandwidth paʻa akā he manawa manawa paʻa ʻole.ʻO ka hāʻawi ʻana i ka bandwidth i hōʻoia ʻia (Assured) kūpono no nā lawelawe bandwidth paʻa ʻaʻole koi i ka jitter kiʻekiʻe, e like me ka wikiō ma nā lawelawe koi.Hōʻike ʻia ʻo Type 3 e ka hōʻoia ʻana o ka bandwidth liʻiliʻi a me ka hoʻokaʻawale ʻana i ka bandwidth redundant, a loaʻa iā ia ka palena o ka bandwidth kiʻekiʻe, e pili ana i ka hāʻawi ʻana i ka bandwidth non-assured (Non-Assured), kūpono no nā lawelawe me nā koi hōʻoia lawelawe a me nā kaʻa pahū nui.E like me ka hoʻoiho ʻana i ka ʻoihana. Hōʻike ʻia ke ʻano 4 e BestEffort, ʻaʻohe hōʻoia bandwidth, kūpono no nā lawelawe me ka haʻahaʻa haʻahaʻa a me nā koi jitter, e like me ka WEB browsing service.ʻO keʻano 5 heʻano hui pū, ma hope o ka hoʻokaʻawaleʻana i ka bandwidth i hōʻoiaʻiʻoʻia a me kaʻole i hōʻoiaʻiʻoʻia, hoʻonui Hoʻokaʻawaleʻia nā koi bandwidth e like me ka mea hiki.
Ka hopena: ʻoi aku ka maikaʻi o GPON ma mua o EPON
E hana a mālama i ka OAM
ʻAʻole noʻonoʻo nui ʻo EPON no OAM, akā wehewehe wale ʻo ONT i ka hōʻike hewa mamao, loopback a me ka nānā ʻana i ka loulou, a he kākoʻo koho.
Hōʻike ka GPON i ka PLOAM (PhysicalLayerOAM) ma ka papa kino, a ua wehewehe ʻia ʻo OMCI (ONTManagementandControlInterface) ma ka papa luna e hana i ka hoʻokele OAM ma nā pae he nui.Hoʻohana ʻia ka protocol channel OMCI e hoʻokele i nā lawelawe i wehewehe ʻia e ka papa luna, me ka hoʻonohonoho ʻana o ka hana o ka ONU, ke ʻano a me ka nui o ka lawelawe T-CONT, nā ʻāpana QoS, ka ʻike hoʻonohonoho noi a me nā helu hana, a hoʻolaha 'akomi i nā hanana holo o ka ʻōnaehana e hoʻokō i ka hoʻonohonoho o ka OLT i ka ONT.Ka mālama ʻana i ka ʻike hewa, ka hana a me ka palekana.
Ka hopena: ʻoi aku ka maikaʻi o GPON ma mua o EPON
Link layer encapsulation a me ke kākoʻo lawelawe lehulehu
E like me ka mea i hōʻike ʻia ma ka Figure 2, EPON ka hahai ʻana i kahi ʻikepili Ethernet maʻalahi, akā hoʻohui i kahi 64-byte MPCP point-to-multipoint control protocol i ka poʻomanaʻo Ethernet e hoʻokō i ka hoʻokaʻawale ʻana i ka bandwidth, bandwidth round-robin, a me ka ʻike ʻakomi ma ka ʻōnaehana EPON.ʻO ka hana a me nā hana ʻē aʻe.ʻAʻole nui ka noiʻi e pili ana i ke kākoʻo o nā lawelawe ʻē aʻe ma mua o nā lawelawe ʻikepili (e like me nā lawelawe synchronization TDM).Nui nā mea kūʻai EPON i hoʻomohala i kekahi mau huahana maʻamau ʻole e hoʻoponopono i kēia pilikia, akā ʻaʻole kūpono lākou a paʻakikī ke hoʻokō i nā koi QoS papa lawe.
Kiʻi 2: Hoʻohālikelike i nā pūʻulu protocol GPON a me EPON
Hoʻokumu ʻia ʻo GPON ma luna o ka ʻāpana transport convergence (TC) hou loa, hiki ke hoʻopau i ka hoʻololi ʻana o nā lawelawe like ʻole kiʻekiʻe.E like me ka mea i hōʻike ʻia ma ka Figure 2, wehewehe ia i ka encapsulation ATM a me ka encapsulation GFP (general framing protocol).Hiki iā ʻoe ke koho ʻelua.ʻO kekahi no ka encapsulation ʻoihana.I ka ʻike ʻana i ka kaulana o nā noi ATM i kēia manawa, loaʻa kahi GPON e kākoʻo wale ana i ka encapsulation GFP.Ua hoʻokumu ʻia ka hāmeʻa liʻiliʻi, e wehe ana i ka ATM mai ka waihona protocol e hōʻemi i nā kumukūʻai.
ʻO ka GFP kahi kaʻina hana papa loulou maʻamau no nā lawelawe he nui, i wehewehe ʻia e ka ITU e like me G. 7041. Ua hana ʻia kahi helu liʻiliʻi o nā hoʻololi i GFP ma GPON, a ua hoʻokomo ʻia ʻo PortID ma ke poʻo o ka frame GFP e kākoʻo i ka multi-port multiplexing.Hoʻokomo pū ʻia kahi hōʻailona māhele Frag (Fragment) e hoʻonui i ka bandwidth kūpono o ka ʻōnaehana.A kākoʻo wale ia i ke ʻano hoʻoili ʻikepili no ka ʻikepili lōʻihi ʻokoʻa a ʻaʻole kākoʻo i ke ʻano hana hoʻoili ʻikepili no nā poloka ʻikepili.Loaʻa i ka GPON ka mana lawe nui lawelawe.ʻO ka papa TC o GPON ka mea like me ka synchronous, me ka hoʻohana ʻana i ka 8 kHz maʻamau (125μm) nā papa lōʻihi paʻa, e hiki ai iā GPON ke kākoʻo i ka manawa hopena a me nā lawelawe quasi-synchronous ʻē aʻe, ʻoi aku hoʻi no ke kākoʻo pololei ʻana i nā lawelawe TDM, ka mea i kapa ʻia ʻo NativeTDM.Loaʻa iā GPON ke kākoʻo "kūlohelohe" no nā lawelawe TDM.
ʻO kēia hopena: ʻO ka papa TC e kākoʻo ana i ka GPON no nā lawelawe lehulehu ʻoi aku ka ikaika ma mua o ka MPCP o EPON.
Ka hopena
Loaʻa iā EPON a me GPON kā lākou pono ponoʻī.ʻOi aku ka maikaʻi o GPON ma mua o EPON ma ke ʻano o nā hōʻailona hana.Eia nō naʻe, loaʻa iā EPON ka maikaʻi o ka manawa a me ke kumukūʻai.Ke hopu nei ʻo GPON.ʻO ka nānā ʻana i mua i ka mākeke komo broadband e hiki mai ana ʻaʻole ia he pani, pono ia e hoʻokō.No ka bandwidth, multi-service, QoS kiʻekiʻe a me nā koi palekana, a me ka ʻenehana ATM ma ke ʻano he mea kūʻai hope, ʻoi aku ka maikaʻi o GPON.No nā mea kūʻai me ka haʻahaʻa kumu kūʻai, QoS a me nā koi palekana, ua lilo ʻo EPON i mea nui.