Alien Waves

What are your experiences with alien waves, managed spectrum, spectrum as a service, etc?

It’s one of those things that makes a lot more sense on paper than in practice. I’ve found it to be operationally difficult from the perspective the provider and the user, primarily but not solely because any “co-managed” system is going to lend itself to finger pointing when issues arise. Even if it makes more commercial sense at first blush to prefer a spectrum solution over dark or traditional waves, I suspect that factoring in “labor cost wasted over unproductive troubleshooting” changes the equation a bit. I also suspect that continued price compression on optical hardware will lead to fewer and fewer situations where it might make commercial sense at first blush too.

YMMV of course and there may be reasons beyond simple commercial models where spectrum might make sense for you, but I’d urge you to only consider it doing with a provider where you’ve had a track record of operational success working with them.

Dave Cohen

Your outcomes will vary depending on whether this is deployed for terrestrial or subsea networks. Subsea networks don’t typically do alien waves, but rather, managed spectrum or spectrum sharing. This is especially the case on the newer SDM-based uncompensated submarine cable systems, where there is a huge volume of fibre pairs that makes this feasible, if not the most economical way to sell the asset to volume customers. For terrestrial, alien waves were the original model, and in my opinion, the preferred one, because all the host network has to do is provide a port on their filter with a wavelength. The filter isolates the adjacent signals from one another, which improves launch OSNR. That said, managed spectrum and spectrum sharing are quickly replacing alien waves as the preferred deployment option for terrestrial networks, which can largely be blamed on advances for the same happening on the submarine side of things, even though the original idea was mostly driven by GEANT and a bunch of European NREN’s back in the day. Managed spectrum and spectrum sharing are more problematic because the chance of broadcasting bad noise to all other channels increases. Yes, major DWDM vendors now do have significantly improved optical power management systems (a spectrum controller, let’s say) that will interact with the WSS in their ROADM, where the ROADM will set the centre frequency and its width, which helps to restrict any negative impact to launch insertion, and not toward the line side. Different vendors will have different spectrum controller options that make managed spectrum and spectrum sharing services either simple or difficult to deliver on their specific type of gear. If it is something you want to be serious about, this will be the one time where PoC’ing all the vendors you are interested in is worth your time. It would also be useful to understand how each vendor supports things such as T-API (Transport-API) and other OpenROADM open architecture features to improve wavelength and optical power management characteristics between different vendors sharing a single OLS (Optical Line System). You may find that support for T-API and other OpenROADM standards may be spotty to non-existent with many vendors, but a vendor with a solid roadmap is certainly not a waste of your time. Major traditional vendors like Ciena, Infinera, Nokia, Adva, Ribbon, and such, will have very extensive spectrum controllers, but they will come with the requisite $$ premium. Newer vendors whose platforms are based primarily on coherent pluggables approved by the MSA and OpenROADM will support alien waves, but may struggle to offer a comparable spectrum controller solution for managed spectrum and spectrum sharing, even if they may have a rudimentary ability to do so. Due diligence is highly warranted here, as the landscape is changing on a daily basis. In essence, “virtual fibre pair services” (if I can call them that) is a matter of security, by way of total optical power control. What you want the vendors you consider to answer is:

Not anymore. The majority of SDM subsea cables built with uncompensated fibre are using managed spectrum and spectrum sharing as viable business models for a not-so-insignificant population of their customer base. And there is a case to be made for that concern. However, if you are in a position to be able to sell spectrum, it is very likely you are going to be implementing a vendor of note. Since that is most likely to be the case, those vendors have spectrum controllers that make this a viable business model, albeit at a $$ premium. This is not the type of service small DWDM operators using new-age DWDM vendors would typically be looking to sell. Such operators have to deal with keeping the lights on, never mind esoteric services like spectrum. Alien wave and spectrum services attract a very high income, mainly through a capex-based upfront cost (IRU) that can be attractive to the host network. At those levels, providing their vendor has decent support for spectrum services, the revenue gain more-than makes up for all the logistical admin. Well, legacy DWDM vendors will continue to charge a premium even for what is now standard electrical bandwidth services. Why? Because they still have all that legacy stuff to support, all their R&D to recoup, and because the bulk of their customers are no longer the telco, but content folk. New-age DWDM vendors are focused on coherent optical networks, which are primarily 100G and 400G. Why? Because that is where MSA and OpenROADM are currently at re: commercial availability. The legacy vendors will develop proprietary coherent pluggables that will support funky things such as 800G, 1.2T and 1.6T, but those won’t be industry standard for some time (800G is getting there, though). What all this means is that if you are a legacy operator that is careful about spending money on newer DWDM technologies, a spectrum service from a larger carrier is going to be more attractive than ripping out your entire line system just so you can get from 10G or 40G to 400G. Of course, if you are a monopoly and have no alternatives to lean on, this doesn’t count. New-age DWDM vendors are not the workhorse of most of the large DWDM operator networks out there. That means that any operator of note you are likely to run into is going to be a Ciena, Infinera, Nokia, Adva, e.t.c., house, or something along those lines. Those vendors have reasonable spectrum-based solutions that smaller DWDM operators or ISP’s would be willing to spend money on to avoid having to upgrade or deploy an entire line system. The reason that is feasible is because those larger operators are running vendors who push beyond what the MSA and OpenROADM groups are prescribing. You can already get coherent 100G and 400G channels on new-age DWDM vendors… that is not rocket science anymore. Of course, there is always the IPoDWDM question… but if I’m honest, I am still as unconvinced now in 2024 as I was back in 2008 that optical and IP folk would have a meeting of the minds on this. Mark.


Many/all of these points are fair. My experience is purely terrestrial and obviously both the capacity and economic calculations are vastly different in those situations, which I should have called out.

However, I don’t think that the optical vendor is really the challenge - I would agree that, generally, spectrum is going to be available through larger providers that are using “traditional carrier grade” platforms - but rather at the service provider level. When something invariably breaks at 3 AM and the third shift Tier I NOC tech who hasn’t read the service playbook says “I don’t see any errors on your transponder, sorry, it’s not on our end” because they’re not aware that they actually don’t have access to the transponder and need to start looking elsewhere, that’s the sort of thing that creates systemic challenges for users regardless of whether the light is being shot across a Ciena 6500 or a Dave’s Box-o’-Lasers 1000.

Dave Cohen

Actually, terrestrial economics are easier to consider because you have the one thing the subsea applications don’t have in abundance… power. Fair point, terrestrial revenues are significantly lower than subsea revenues on a per-bit basis, but so are the deployment costs. That evens out, somewhat. I think you are contradicting yourself a bit, unless I misunderstand your point. Legacy vendors who have spectrum controllers have made this concern less of an issue. But then again, to be fair, adopting spectrum controllers along with bandwidth expansions via things like gridless line systems and C+L backbone architectures that make spectrum sales a lot more viable at scale do come at a hefty $$ premium. So I can understand that offering spectrum independent of spectrum controllers is going to be more trouble than it is worth. Ultimately, what I’m saying is that technologically, this is now a solved problem, for the most part. That said, I don’t think it will be the majority of DWDM operators offering spectrum services en masse, for at least a few more years. So even if you want to procure managed spectrum or spectrum sharing, you are likely to come up against a limited set of providers willing to sell it, if at all. Mark.

"a limited set of providers willing to sell it, if at all."

I know of one (Windstream) that offers it on a portion of their footprint. I swore others did, but I couldn't find them. Does anyone know who else in the NANOG area who does this?

My point was that the technology has little to do with the operational success of the service. Spectrum controllers better enabling providers to get out of their own way in selling spectrum did not actually enable the providers* to get out of their own way in selling spectrum. It should be easier than it used to be, but it isn’t, and the problem is not really technical, but a question of 1) not having full-throated commitment to wanting to sell spectrum and 2) not having the talent to support it, which is really just a function of #1.

*Speaking specifically about the very largest CLEC wavelength providers in North America

There are some single-market/regional providers that I’m aware of currently offering spectrum, but I believe you’ll be hard pressed to find others with national footprints in the US that will. Zayo and Lumen both did a bit of a will they/won’t they with it for a long time, and my understanding is that neither of them currently offer it, or at least will tell you that publicly.

I engaged Zayo about some spectrum and/or a single alien wave between a couple of "nearby" regional PoPs a couple years ago and got told pretty unequivocally that, despite it being in their service catalog, productized, and even having some form of standard pricing, they did not want to actually offer it.

I doubt that's changed given my dealings with them since (which have been fine, to be clear), but I can't be 100% sure. I suspect they did at least turn up a few of them given that they went to the trouble of creating a full-fledged product for it. Maybe they found out the hassle wasn't worth it?

Fundamentally, I agree.

This is one area where terrestrial operators will be late bloomers, as subsea shows and leads the way.

My prediction is that there will be a slightly improved chance of spectrum services gaining a little more traction (not a lot) on the terrestrial side when the new-age DWDM vendors are able to offer more competitive and standards-based spectrum controllers.

The other avenue of interest will be in mitigating the costs associated with upgrading to C+L network topologies, where some spectrum comes up for grabs as a quick way to recover the investment.

And lastly, content folk looking to enter markets on the back of existing operators where the appetite for negotiating dark fibre is relatively low, will apply pressure on those reluctant operators to offer up some spectrum. We have already seen, across the world, how "convincing" the content folk have been at this sort of thing.

But for the most part, yes, I expect the bulk of DWDM services sold to terrestrial network users will continue to be electrical bandwidth, and not optical spectrum, at least for the next few years. I could potentially see a case for a specialist DWDM operator who focuses on a spectrum-based service network that sells to 3 - 5 high-capacity customers, but those will be very specialist.


The upfront cash you get is great to make the quarter's/year's number in one go, but after that, all you are earning is annual O&M, which is not a lot especially if you still have to spend quite a bit maintaining the outside plant. And once that spectrum is gone, you can't touch it again even if the customer you sold it to may not be using all of it at the time.

Electrical bandwidth is slow to shift, but it is stable monthly/quarterly revenue that you can bank a business plan on.


Depends on the equipment but works just fine. I have tested Ciena Waveserver/AI and Ekinops equipment as alien wave into an existing Cyan ROADM system without a problem. Usually just make sure your TX power is 0 or +5 + whatever the minimum for the ROAM system to pick it up.