Low to Mid Range DWDM Platforms

Sat Oct 21 05:43:35 UTC 2023

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.