Ndi chitukuko cha kuyankhulana, chidziwitso chofunikira kuti chifalitsidwe sichimangokhala mawu, komanso malemba, deta, zithunzi, ndi mavidiyo.Kugwirizana ndi chitukuko cha kulankhulana kwa digito ndi luso lamakono la makompyuta, m'ma 1970 ndi 1980, T1 (DS1) / E1 makina onyamula (1.544 / 2.048Mbps), X.25 frame relay, ISDN (Integrated Services Digital Network) ndi FDDI ( Optical fiber kugawa mawonekedwe a data) ndi matekinoloje ena amtaneti.Kubwera kwa gulu lachidziwitso, anthu akuyembekeza kuti maukonde amakono otumizira zidziwitso atha kupereka mabwalo ndi mautumiki osiyanasiyana mwachangu, mwachuma, komanso moyenera.Komabe, chifukwa cha monotonicity ya mautumiki awo, zovuta zowonjezera, ndi kuchepa kwa bandwidth, zomwe tatchula pamwambapa matekinoloje amangokhala m'makonzedwe oyambirira a Zosintha kapena kusintha mkati mwa chimango sikuthandizanso.Zithunzi za SDHidapangidwa pansi pa maziko awa.Pakati pa matekinoloje osiyanasiyana a Broadband optical fiber access network, njira yolumikizira netiweki yogwiritsa ntchito ukadaulo wa SDH ndiyomwe imagwiritsidwa ntchito kwambiri.Kubadwa kwa SDH kumathetsa vuto la kulephera kupitiriza ndi chitukuko cha makina a msana ndi zofunikira za utumiki wa ogwiritsira ntchito chifukwa cha kuchepa kwa bandwidth kwa mauthenga olowera mkati, ndi vuto la kupeza "bottleneck" pakati pa wogwiritsa ntchito ndi core network. , ndipo panthawi imodzimodziyo, yawonjezera kuchuluka kwa bandwidth pa intaneti yotumizira.Mtengo wogwiritsa ntchito.Kuyambira kukhazikitsidwa kwaukadaulo wa SDH m'zaka za m'ma 1990, yakhala ukadaulo wokhwima komanso wokhazikika.Amagwiritsidwa ntchito kwambiri pama network am'mbuyo ndipo mtengo ukucheperachepera.Kugwiritsa ntchito ukadaulo wa SDH mu netiweki yofikira kumatha kuchepetsa bandwidth yayikulu pamaneti oyambira.Ubwino ndi luso luso amabweretsedwa m'munda wa maukonde mwayi, kugwiritsa ntchito mokwanira SDH synchronous multiplexing, standardized kuwala mawonekedwe, mphamvu maukonde kasamalidwe luso, kusintha maukonde topology luso ndi kudalirika mkulu kubweretsa phindu, ndi phindu kwa nthawi yaitali mu zomangamanga ndi kukulitsa ma network ofikira.