using SMF 20KM reach SFP instead of already exisitng 10KM reach

[from88]

Hello,

Is there any dangers of using 20KM SMF SFP instead of already existing 10KM SFP reach ?

Thanks

[balaji.bandi]

As long as you have right Optic LR and fibre available you can use.

[from88]

So that means i could not have issues with 'too much' TX power due to more powerful SFP ?

[Joseph W. Doherty]

I haven't doubled check, but I recall only the 80 KM optics really should have attenuation when being used under certain distances. Of course, for the lessor optics, there still minimum lengths, but that, I also recall, is when use down at typical patch panel lengths.

[from88]

Problem is that we dont know where exactly other side on the cable is - because it's a DC connection to patch panel to some ISP. Anyway - thank you all, i made a conclusion that little bit more TX power should not hurt our current connections. 

Also - digging into that i got two new random generated questions:

1) As we know - SMF fibers comes with 1310nm or 1550nm (for longer distances than 20km). So just to confirm to myself they (1310nm and 1550nm) would not work in the same connection, right ?

2)Question about CWDM: In CWDM wavelength range there're also 1310nm and 1550nm  wavelengths  as in 'simple' SMF connections. So - theoretically - would simple SMF with 1310nm or 1350nm ranges work in CWDM connections ? Or i still need a special CWDM SFP to work even in 1310nm and 1350nm  ranges ? Thank you.

[balaji.bandi]

You need to find out the requirement both the side along with Service provide who provide DWDM link to you or Dark Fibre, what presentation they looking to presend you to connect.

if the provider network, they do their bit, you need to look only NTU to your end device.

here is cisco good document for refenece what model of SFP required where :

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/white_paper_c11-463661.html