On 10/19/23 22:24, Chad Lamb via NANOG wrote:
XKL is still here ...
Some caveats on 400G ZR/ZR+ devices:
- They are power hungry, cooling is a challenge. 800G even more so.
The OSFP package for 800G looks like the better choice than QSFP-DD
for this reason. We'll see, we need more mileage on this.
- For the ZR devices, not all vendors are equal. Some support 4x100GE
as well as 400GE, if that matters to you. Some have integrated BERT
and encryption, some do not.
- Do not plan on inter-operating different vendors of ZR+ devices.
They will interoperate only in ZR mode.
- Plenty of filter options out there if you are putting the ZR/ZR+ in
your router. I'll throw a plug in for the Coherent free space DWDM
filter. Free space technology has the best IL and isolation numbers.
Coherent hasn't packaged it in a module for easy racking yet (XKL can
provide that). So if you aren't adding an EDFA, the lowest IL you can
get helps your reach.
- If you have at least a few 400G channels, add an EDFA and use the Tx
= -10dBm devices, rather than the Tx = 0dBm devices. This is cost
effective. The EDFA also extends the reach considerably. You can
launch each channel up to +10dBm or more, for a modest number of
channels, without getting in trouble with fiber non-linearities
(four-wave mixing).
Many thanks, Chad.
Glad to hear XKL are still in business, and doing well :-).
Mark.
