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Can sfp singlemode 1310nm and 1550nm be connected?

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From the previous article we already discussed about can we use sfp multimode on singlemode fiber.
Link :



There is one case in customer, where they needed transceiver 40G 80KM with different type. Interface A use transceiver type CFP 40G 1550nm 80KM and interface B use transceiver type QSFP 40G 1310nm 80KM. From this case there are wavelength differences, 1310nm with 1550nm, what is the impact on the network or traffic data ?

The impact is probably the link will be UP but the traffic data will be disturbed, its caused wavelength differences, data send with wavelength 1310nm can’t receive well with wavelength 1550nm and vice versa.

It was proved by BIDI transceiver (Bidirectional) concept, BIDI transceiver is working only with just one cable strand, BIDI transceiver has different wavelength for the transmit and receive, how they work is connecting two SFP that has opposite wavelength. For the example SFP BIDI A Tx1310nm/Rx1550nm must be connected with SFP BIDI B Tx1550nm/Rx1310nm.

From the transceiver BIDI concept, we can conclude that the traffic data was running on one cable strand will not meet each other because wavelength differences. Please refer to the image below.

Back to customer question above, when connecting tranceiver CFP 40G 1550nm 80KM with transceiver QSFP+ 40G 1310nm 80KM, data will not meet each other. So the concept cannot be use.

Conclusion :

  • We must use the correct SFP and cable type
  • We must use the correct wavelength.