40G and 100G optics options
hugge at nordu.net
Mon Dec 18 17:49:37 CST 2017
This is the "failure" of us (the business) choosing QSFP as the de-factor formfactor for 100G, there is not power in
that cage to make 10km+ optics in an easy way. If we would have pushed for CFP4 as the "last" formfactor in 100G land we
would be much better off.
The options you have to choose from realistically is QSFP28-ER4L
It exist in a fec and non-fec option that does 30 and 40km respectively although a few vendors spec them at 25km cause
its really hard to validate them in their upper ranges. But this is quite and expensive optic.
On the horizon you have QSFP28-4WDM20 and 4WDM40 which uses FEC. Not sure where the MSA stands on that.
If you need more then 30-40km reliable stuff you need to either to PAM4 (The "Inphi ColorZ" optic) which is 80km at
best. These should not be confused for the regular 10G ZR-optics with a fixed lambda you can buy for $300 from china.
These are dual-laser optics that runs two 50G PAM4 carriers with very low launchpower. They need pre and post-amps
aswell as tuned DCM and a MUX to fully work. Also they are fixed wave so you need 44 different optics to populate a full
MUX. These optics are great if you need tons of 100Gs on very short metro-spans.
It always almost ends up with coherent being the better option in the end anyway if you wanna go beyond 20-25km. There
is like 30 different competing products on the market now that acts as a stupid little transponder with a QSFP28 in one
end (where you plug your DAC in) and a CFP2-ACO (or DCO) in the other end that let you run a couple of hundred
kilometers (or thousands) with a proper coherent DWDM signal.
Now that CFP2-DCO is GA finally i hope to see more linecards and switches that has CFP2 slots in them.
> What options are available for 40G QSFP+ and 100G QSFP28 for 10+ km links?
> I see a lot of switches offered with QSFP+ and QSFP28. But I do not seem
> to find the necessary optics to build the links I want.
> For example, take a look at the options available at Fiberstore:
> Generic Compatible 40GBASE-LR4 and OTU3 QSFP+ 1310nm 10km LC Transceiver
> for SMF
> Generic Compatible 40GBASE-ER4 and OTU3 QSFP+ 1310nm 40km LC Transceiver
> for SMF
> Generic Compatible QSFP28 100GBASE-LR4 1310nm 10km Transceiver
> Generic Compatible QSFP28 100GBASE-ER4 1310nm 40km Transceiver
> That is it. Four modules and the 40km are prohibitive expensive. The
> situation at other vendors appears to be similar.
> I need stronger modules that can do more than 10 km without being
> extremely expensive. Or DWDM modules in the 1550 nm band so I can use
> external amplifiers. Am I looking in the wrong place? Is this expected
> to be available in the near future?
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