for Upgrade Figure 5-9 Coupler or Spare Wavelength Basic DWDM multiplexing method. Wavelengths Amplifier Wavelengths Expansion Port for Upgrade Coupler or Spare Wavelength DCM = Dispersion Compensation Module Figure 5-10 Pictorial view of WDM. Wavelength Wavelength DeMux 1 12 3 4 11 12 13 14 11 2 13 4 throughput, they currently suffer from technical, engineering, and cost drawbacks. Therefore, WDM methods have enjoyed significant market pen- etration in the long-haul segment in the United States and abroad. Figure 5-10 provides a pictorial view of WDM. Figure 5-11 depicts the progression of throughput in WDM systems over the past few years. The following list depicts the evolution of transponder technology in the recent past:12 Capacity OC-48 OC-192 OC-768 Spacing 400 GHz 200 GHz 100 GHz 50 GHz 25 GHz Bit rate transparent Issues-Jitter problem and performance monitoring SONET rate transponder Jitter compliant Issues-B1/JO monitoring, fault isolation, and misconnections Dense Wavelength Division Multiplexing (DWDM) Systems Figure 5-11 320 Gbps Bandwidth OC-192, 32 Wavelengths improvement for long-haul systems over time. 200 Gbps Hybrid OC-48/OC-192, 32 Wavelengths 160 Gbps OC-192, 16 Wavelengths 100 Gbps Hybrid OC-48/192, 16 Wavelengths 80 Gbps 50 Gbps OC-48, Hybrid 32 Wavelengths OC-48/192, or OC-192, 8 Wavelengths 8 Wavelengths 25 Gbps Hybrid OC-48/192, 40 Gbps 4 Wavelengths OC-48, 16 Wavelengths or OC-192, 4 Wavelengths 20 Gbps OC-48, 8 Wavelengths or OC-192, 2 Wavelengths 10 Gbps OC-48, 4 Wavelengths or OC-192, 1 Wavelength 5 Gbps OC-48, 2 Wavelengths 2.5 Gbps OC-48, 1 Wavelength Chapter 5 Section-terminating equipment (STE) transponder Full-compliant SONET STE Software configurable (B1/JO) Line-terminating equipment (LTE) transponder Muxing and add/drop OC-48 and OC-192 Path-terminating equipment (PTE) transponder Mapping new services (such as Gigabit Ethernet [GbE]) into SONET frames The proliferation of bandwidth-intensive applications has steadily dri- ven the demand for broadband connectivity and transpor