This content summarizes all the SDH veneers, PDH veneers and data class veneers of OptiX OSN series products that support various types of loopbacks.The support capability of SDH veneers in OSN series products for loopbacks is shown in Table 1. "Y" indicates that the board supports the function, and "N" indicates that the board does not support the function.

OSN2500 transmission equipment PDH single board loopback description

Single Board	Inside Port Loopback	Port Outer Loopback
R1PL1	R1PL1	R1PL1
R1PD1	R1PD1	R1PL1 Y Y
R3PD1	R3PD1	R3PD1 Y
N1PQ1	N1PQ1	N1PQ1 Y
N1PQM	N1PQM	N1PQM
N2PQ3	N2PQ3	N1PQM Y
N1PD3	N1PD3	N1PD3 Y
N1PL3	N1PL3	Y
N2SPQ4	N2SPQ4	Y

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