Dense Wavelength Division Multiplexing (DWDM) is a transmission technology that enables greater fiber capacity, longer transmission distances, and higher data rates by multiplexing multiple wavelengths into a single fiber
DWDM is used in telecom networks, data centers, as well as in enterprise networks, providing a scalable solution to meet growing data rate demands.
This test case was developed to verify reliable PTP operation over coherent ZR/ZR+ DWDM optics installed in the Telecom Boundary Clocks, ensuring that transport solutions meet scalability and performance requirements.
At this year's testing event, we had more vendors, five in total, supporting PTP over DWDM-enabled tunable ZR/ZR+ optics compared to last year’s testing event.

For all the tests, the setup consisted of a Telecom Grandmaster (T-GM), two cascaded Telecom Boundary Clocks (T-BCs), and a frequency/phase analyzer.
For some test cases, an emulated T-GM was used: either the Calnex Paragon neo, Calnex Paragon neo-A, or the Keysight Time Sync Analyzer. In those tests, the same device that served as the emulated T-GM also served as the frequency/phase analyzer. For other tests, a real T-GM, the Microchip TimeProvider® 4500, was used in combination with either the Calnex Paragon neo or Calnex Paragon neo-A. These tests were run with either a 100 or 400 Gigabit Ethernet (GbE) tunable ZR/ZR+ DWDM optic between the two T-BCs, with the links between the T-GM and T-BC-1 and T-BC-2, and the frequency/phase being standard grey optics.
All combinations tested met the limits for Class C media converter pairs, as per ITU-T G.8273.2, Appendix V, table V.1, with some combinations even meeting the max|TE_L| limit of 10 ns for two Class D T-BCs.
These results show that modern T-BCs and coherent pluggable optics do not cause compliance issues with high-accuracy time synchronization. The findings suggest that T-BCs, synchronized via coherent ZR/ZR+ DWDM optics, can meet the stringent phase and time synchronization requirements common in modern networks, proving that high-capacity optical transport and precise time synchronization can coexist without sacrificing performance.

Table 68: PTP over 100GbE DWDM link

Table 69: PTP over 400GbE DWDM link