Low to Mid Range DWDM Platforms

I've been using various forms of passive WDM for years. I have a couple different projects on my plate that require me to look at the next level of platform.

In some projects, I'll be looking for needing to have someone long distances of glass without any electronics. Some spans could be over 60 miles.

In some projects, I'll need to transport multiple 100-gig waves.

What is the landscape like between basic passive and something like a 30 terabit Ciena? I know of multiple vendors in that space, but I like to learn more about what features I need and what features I don't need from somewhere other than the vendor's mouth. Obviously, the most reliability at the least cost as well.


400G-ZR pluggables will get you 400Gbps on a p2p dark fibre over 80km - 100km. So your main cost there will be routers that will support.

The smallest DCI solution from the leading DWDM vendors is likely to be your cheapest option. Alternatively, if you are willing to look at the open market, you can find gear based on older CMOS (40nm, for example), which will now be EoL for any large scale optical network, but cost next to nothing for a start-up with considerable capacity value.

There is a DWDM vendor that showed up on the scene back in 2008 or thereabouts. They were selling a very cheap, 1U box that had a different approach to DWDM from other vendors at the time. I, for the life of me, cannot remember their name - but I do know that Randy introduced them to me back then. Maybe he can remember :-). Not sure if they are still in business.





My experience is primarily with the traditional carrier-grade folks like Ciena, Infinera, etc. but over the last decade all of those vendors have focused on improving how they scale down without sacrificing (most of the) quality and functionality - to varying degrees of success. There are also some more recent entrants that built their products to target the DCI market but rather than focusing on bandwidth density have focused on cost per bit for a mid-range solution. There are almost definitely multiple quality options out there without having to buy the full 88 channel n-degree ROADM Ciena 6500 that takes up a full rack - although given the stated requirements, there may not be a one-size-fits-all solution that’s ideal for all of the OP’s projects.

One of my clients is Calient Technologies:

Their S320 optical switch is entirely photonic — no electrical transceivers in any optical path at all — using 3D MEMS technology. It’s great for reliable multi-lambda provisioning, and sports built-in power monitoring and passive network diagnostics. It doesn’t do DMDM itself, but it is a great way to automate DWDM traffic engineering with real-time optical path provisioning. It’s essentially a zero-latency 400 Mbps matrix switch.


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On the same topic, anyone have experience with the stuff from fs.com?

Solid Optics? – https://www.solid-optics.com/product/edfamux-multiplexer-amplifier-dispersion-compensation-dwdm-mux-edfa/

I have several of the Smart Optics DCP-M40’s in place. If you are using coherent 100G DWDM optics, you can push the M40-ZR’s to 100-120km. The exact reach depends, of course, on the quality of the fiber plant in use.

Not them.

I want to say they had an "X" in their name, but memory is fuzzy.


There are two markets driving the major vendors right now - DCI and subsea.

The regular longhaul terrestrial gear is mostly the same, bar for upgrades to the latest CMOS. For these vendors, the same gear is also re-used for their subsea solutions, although with "submarine" versions of their terrestrial line cards.

Adva's TeraFlex is a bit different in that it is optimized both for DCI and longhaul terrestrial. We are currently looking at it for a 700km deployment in one of our markets. Very impressive!

Another entrant into the market is Acacia, now known as the Cisco NCS1000. They also use the same platform for both terrestrial and subsea:


Well, and that’s kinda where I was going.

I’ve used FS passive systems for years. FS has an active platform or two (that I understand, they just whitebox). Does it really do everyone one would need to do? How much of a step is it to get something more?

I’ll throw another in the hat for SmartOptics… great products and support. We have a good deal of their stuff for local regional deployments and it’s super reliable, even at over 100km on a mediocre dark fiber span.

I have found that for low end DWDM solutions, https://www.packetlight.com/ has always been the cheapest available.


Finally, the name came to me :-):


Looks like they are still in business.


Yeah, was looking at their active solution for a customer, but just don’t know enough about it to go that route.


On the same topic, anyone have experience with the stuff from fs.com?

On the same topic, anyone have experience with the stuff from fs.com?

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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 :-).


Sorry for the late response, but I can speak about the FS M6200 product. We have been using the 10GOEO card for 10G DWDM/WDM on a span. The hardware works reasonably well though we had to reseat a card once in the last 18 months or so of operation. It also seems to be a bit finicky when you first install a new card. Their support had us slot/reslot and move around a few times before things started working as expected. My biggest complaint is that the ONLY way to manage the box is through the EMS system, which must be installed on a windows OS. It has an embedded apache server that provides the interface, so it doesn’t have to run on windows server. The EMS uses SNMP for all the configuration of the hardware itself. We figured out how to do some basic things like change the IP using snmp, but besides, that there is no way to manage it without connectivity back to the EMS, no CLI, no internal web interface, etc.

Collin R