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fperezromero
Beginner

Non tunables DWDM SFP+ reach

Reading the SFP + DWDM datasheet, it is not clear to me what is the reach of non-tunables SFP+ as DWDM-SFP10G-61.41=

 

I understand that the ditance is limited by the loss of optical fiber and chromatic dispersion but, what could be the distance in the best of cases? 40 kilometers?. 80 Km?

 

The same thing happens to me by reviewing the SFP DWDM's datasheet.:
https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/dwdm-transceiver-modules/product_data_sheet0900aecd80582763.html

It indicates: "When shorter distances of single-mode fiber are used, it might be necessary to insert an optical attenuator in the link". Shorter than how much?

Thanks in advance.

P.D: Sorry my poor english

1 ACCEPTED SOLUTION

Accepted Solutions

at 1m you will need an attenutator, but yes up to 80km and a tad bit longer if the fiber is good

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4 REPLIES 4
Joseph W. Doherty
Hall of Fame Expert

If I remember correct, up to 80 Km should be possible.

Search for attenuator recommendations in: https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-455693.pdf
Jafar Tavana
Beginner

you can use this SFP+ Maximum distance 80 Km, you can use it for 1 meter optical cable patch cord or 79.99 Km.

at 1m you will need an attenutator, but yes up to 80km and a tad bit longer if the fiber is good

View solution in original post

Tom Randstrom
Rising star

The same thing happens to me by reviewing the SFP DWDM's datasheet.:
https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/dwdm-transceiver-modules/product_data_sheet0900aecd80582763.html

It indicates: "When shorter distances of single-mode fiber are used, it might be necessary to insert an optical attenuator in the link". Shorter than how much?

For long reach optical transceivers, the transmitters optical output power is greater than the receiver's input power range. To use the DWDM transceiver you linked to, this module has a transmit output power of +4dBm (max) which the receiver's input range is -9 to -28dBm. 

 

To calculate the minimum attenuation required for this link to operate correctly:

Transmit power (+4dB) minus Receiver input power (-9dBm) = Minimum link attenuation (+13dBm).

Fiber loss is ~ 0.25dB/km (@1550nm). So, 13db / 0.25dB/km =  52km minimum link length. So if you are doing bench testing, it would be necessary to add a minimum of 13dB of attenuation to have the received power level to fall within the receiver's operating range (-9dBm to -28dBm).  

 

Let us know if you have additional questions.