User side Network side PSTN E1:2M,E2:8M, TDM-based 64kb/s (digital telephone) E3:34M,E4:140M (PDH rates only for European 2 Mbps,8 Mbps,FE(100M STM-N#,N=1,4,16, broadband Ethernet),GE(Gigabit Enet) 64,256{SDH155M, network STM-0(51.84Mbps,aka OC-1 622M,2.5G,10G,40G} means Optical carrier at level xGE,X=1,10,100,200 one in SONET),STM-1 1/10/100/200GE (155.52Mbps) Comments: √ PDH(Pleisochronous Digital Hierarchy,准同步数字系列/体系) was widely used in 1980's.It has three systems with the transmission rates up to 140Mbps.Its E1 has some applications,especially in PSTN. √ SDH#(Synchronous Digital Hierarchy)and Ethernet#have been used widely in various networks from access,metropolitan to core.SDH's transmission rates are abbreviated as STM-N#,meaning SynchronousUser side Network side PSTN TDM-based 64kb/s (digital telephone) E1: 2M, E2: 8M, E3: 34M, E4: 140M (PDH rates only for European ) broadband network 2 Mbps，8 Mbps，FE(100M Ethernet), GE( Gigabit Enet) STM-0 (51.84Mbps, aka OC-1 means Optical carrier at level one in SONET ), STM-1 (155.52Mbps) STM-N# , N=1, 4, 16, 64,256 {SDH 155M, 622M, 2.5G,10G,40G} xGE, x=1,10,100,200 1/10/100/200 GE Comments:  PDH (Pleisochronous Digital Hierarchy，准同步数字系列/体系) was widely used in 1980’s. It has three systems with the transmission rates up to 140Mbps. Its E1 has some applications, especially in PSTN.  SDH#(Synchronous Digital Hierarchy) and Ethernet# have been used widely in various networks from access, metropolitan to core. SDH’s transmission rates are abbreviated as STM-N#, meaning Synchronous Transfer Module at N level, while the later can be denoted as xGE#