On 7/20/21 4:44 PM, Saku Ytti wrote:

I'm going to hazard a guess that the exhaustive list is empty. Allowing 3rd parties to launch alien waves to your system puts your existing waves at the mercy of the 3rd party, power or lack thereof from the alien wave may impact operation of other waves.

While it might be different for subsea, especially transoceanic, simply due to market factors, I suspect this is the case on most long-haul routes of consequence. Even the carriers I've talked to who have it productized in their sales catalog with documentation as to the responsibilities of all parties essentially refuse to sell it in practice. The only traction I've gotten was if I wanted to buy half the C-band spectrum on a new route not yet lit and was willing to sign a very long-term (20 year-ish) contract for it. Essentially it was treated similar to an IRU on half the bandwidth on the route and came lit end-to-end. They were willing/able to do this since they could use red/blue filters and separate VOAs and OPMs to keep things in check at the entry/exit points of the line system. This isn't really practical if you're dealing with just a couple hundred GHz or have frequent need to add/drop it. -- Brandon Martin

Hi, Alien wavelengths is a fairly old concept and more generally just refers to running any wavelength over a DWDM system that isn't generated by that system's own transponders. These days it is more about leasing spectrum (Spectrum as a Service), but that comes in several different flavours. There is the basic "I want access to 250GHz of C-band to light in whatever way I want", which only tends to happen between consenting networks (e.g. in the R&E space, or between trusted providers), or as trials due to the risks that ytti mentioned. That could be a single contiguous superchannel of spectrum if you have a colourless/flexgrid add/drop system, or 5 x 50GHz individual channels. At the other end of the spectrum (ahem) is managed transponders. This is more suitable for, e.g., the submarine case. You have guaranteed access to a certain amount of spectrum, but the transponders go into the fibre owner's DWDM equipment and are managed by them and you connect to the transponder in much the same way as a traditional circuit. You can theoretically upgrade as newer transponders come out that use spectrum more efficiently, or as demand requires it for a nominal (!) fee to cover the hardware and engineering. There are options between those models, but it's rarely a pricebook item at the moment and will need to be discussed with the providers. It's also usually intended for fairly large requirements. Cheers, Rob