Mi`nh ddang pha?i thie^'t ke^' ma.ng truye^`n so^' lie^.u co' ye^u ca^u su+? du.ng cho ba da.ng sau : lease line, frame delay va` X25 theo ca'c ba.n thi` thie^'t bi. cu?a ha~ng na`o la` to^'t nha^'t ? Hie^.n ta.i co' 3 nha`tha^`u go^`m : ASCOM, NEWBRIDGE va` NET mi`nh kho^ng ro~ ha~ng na`o chie^'m thi. pha^`n tre^n the^' nhie^`u ? Co' ai co' tho^ng tin gi` thi` cho bie^'t nhe' .