Niaj hnub no, SONET / SDH network yog ib qho kev sib txuas lus thoob ntiaj teb uas ua ke nrog WDM (wavelength division multiplexing) cov txheej txheem los xa ntau qhov teeb meem kho qhov muag hla ib qho fiber ntau. Hauv kev sib txuas lus yav tom ntej, kev sib kis ceev tsis muaj kev ntseeg siab ntawm kev tsiv teb tsaws chaw. Kev tshoov siab los ntawm SONET / SDH network, ITU-T (ITU Telecommunication Standardization Sector) tau txhais cov kev thauj khoom kho qhov muag (OTN) kom ua tiav qhov txiaj ntsig zoo tshaj plaws nrog kev pab ntawm WDM thev naus laus zis.
Feem ntau hais lus, OTN yog lub network interface raws tu qauv muab tso rau hauv ITU G.709. OTN ntxiv OAM (kev khiav haujlwm, kev tswj hwm thiab kev saib xyuas) ua haujlwm rau cov neeg nqa khoom kho qhov muag. Nws tso cai rau cov tswv lag luam sib txuas cov tes hauj lwm los ntawm kev thauj mus los ntawm ntau hom kev cai qub qub, thaum muab cov kev hloov pauv uas xav tau los txhawb cov neeg siv khoom yav tom ntej. Tsis zoo li yav dhau los SONET / SDH, OTN yog lub network pob tshab uas muab kev txhawb nqa rau kev sib tham kho qhov muag ntawm WDM. Txij li ntau cov ntaub ntawv thav ntawv tau muab qhwv ua ke rau hauv ib qho chaw hauv OTN, nws tseem hu ua "digital wrapper".
Txoj Cai Ua Haujlwm ntawm OTN
Tej zaum koj yuav xav tias OTN ua haujlwm li cas hauv kev xyaum. Qhov tseeb, nws cov qauv ua haujlwm thiab hom zoo ib yam li SONET / SDH network. Rau txheej muaj nyob rau hauv OTN network: OPU (optical payload unit), ODU (optical data unit), OTU (optical transport unit), OCh (optical channel), OMS (optical multiplex section) thiab OTS (optical transport section).
OPU, ODU thiab OTU yog peb qhov nyiaj siv ua haujlwm ntawm OTN ncej. OPU zoo ib yam li "txoj kev" txheej ntawm SONET / SDH, uas muab cov ntaub ntawv ntawm hom teeb liab mapped rau hauv lub payload thiab daim ntawv qhia qauv. ODU zoo ib yam li "kab nyiaj siv ua haujlwm" txheej ntawm SONET / SDH, uas ntxiv cov kab ke kho qhov muag-theem saib xyuas, ceeb toom cov cim qhia, tsis siv neeg tiv thaiv hloov pauv bytes thiab cov ntaub ntawv sib txuas lus. OTU zoo li "section overhead" hauv SONET / SDH, thiab nws sawv cev rau qhov chaw kho qhov muag lub cev uas ntxiv kev saib xyuas kev ua haujlwm thiab FEC (kev kho qhov yuam kev tom ntej). OCh yog rau kev hloov pauv ntawm cov teeb liab hluav taws xob mus rau qhov teeb meem kho qhov muag thiab hloov kho DWDM wavelength cab kuj. OMS multiplexes ob peb wavelengths hauv seem ntawm OADMs (optical add drop multiplexer). OTS tswj qhov ruaj khov DWDM wavelengths ntawm txhua qhov hauv-kab kho qhov muag amplifier units.
Qhov zoo ntawm OTN
Muaj ntau qhov zoo ntawm OTN. Ua ntej, nws cais lub network tiv thaiv cov kev pabcuam tsis meej los ntawm kev muab cov pob tshab ib txwm thauj ntawm cov teeb liab encapsulating tag nrho cov neeg siv kev tswj cov ntaub ntawv. Secondly, nws ua multiplexing rau optimum muaj peev xwm siv uas txhim khu kev network efficiency. Thirdly, nws txhim kho kev tu lub peev xwm rau cov teeb liab kis tau los ntawm ntau tus neeg ua haujlwm tes hauj lwm los ntawm kev muab ntau txheej kev saib xyuas kev ua haujlwm.
Kev tsiv teb tsaws chaw mus rau kev kub ceev OTN
Nrog rau kev hloov pauv sai ntawm kev sib tham, OTN tus qauv tuaj yeem ncav cuag qhov kev pabcuam nrawm dua. Nws multiplexing hierarchy tso cai rau ib qho kev hloov OTN thiab ib qho WDM platform rau hauv tshuab hluav taws xob thiab hloov cov kev pabcuam qis dua hauv 10 Gbps, 40 Gbps, lossis txawm tias 100 Gbps wavelengths. Qhov no tshem tawm qhov xav tau rau sab nraud wavelength demultiplexing thiab phau ntawv sib cuam tshuam. OTN network yog qhov kev daws teeb meem zoo tshaj plaws rau yav tom ntej kev kub ceev kev sib txuas hauv qhov ntev. Daim duab hauv qab no qhia txog OTN daim duab qhia kev rau kev sib kis ceev.
Xaus
Tau ntau xyoo, OTN tsis tau tso tseg kev txhim kho nws tus kheej. Tsav los ntawm kev xav tau rau kev sib kis ceev, OTN ua ke nrog WDM yog qhov kev xaiv zoo dua hauv kev sib tham. Nws yog ib txoj hauv kev zoo los tsim kom muaj kev thauj khoom kho qhov muag kom haum rau cov kev pabcuam broadband siab.
