It is an indisputable fact that ROADM is useless. Before the 5G is about to start, people are advised not to mention or pick up this expensive and useless network weapon.
The working principle of ROADM is shown in the following figure. A, B and C are three station in a WDM system, of which A and C are Optical Terminal Multiplexing (OTM) stations and B is the ROADM station. The service delivered by station A is carried on the wavelengths of λ1 to λ5, where the wavelengths are like the train carriages, and the service is the goods in the carriages. In station B, wavelengths of λ3 and λ5 are downstream, while wavelengths of λ6 and λ9 carry new service upstream, thus realizing directly pass wavelengths (λ1, λ2, λ4), downstream wavelengths (λ3, λ5) and upstream wavelengths (λ6, λ9) at station B. If it is necessary to change the up-down and pass wavelength of B station, it only needs to be configurated by software, and there is no need to make any changes in hardware.
The Working Principle of ROADM
The principle of ROADM clearly shows that it is only used to flexibly replace wavelengths at a node in the link. Here are three doubts about the use of ROADM.
The complex optical structure of ROADM undoubtedly greatly increases the link loss of DWDM system, and is not suitable for mass adoption in high-level networks.
There are also the following comments about ROADM on the Internet.
Compared with FOADM, ROADM has the following advantages.
The advantages of this assumption are specious. Sometimes we wonder why the industry has such a sophisticated product, but it is flashy. In fact, ROADM is useless.
ROADM is only the spiritual illusion of a generation of technicians. Once deployed, any ROADM network has never been flexibly configured. That means that the industry only adds to the cost and competitiveness of ROADM's deployment without any reason. How puzzling it is!
The optical network is like the earth under our feet and the sky above our heads. The roads on the earth and the routes in the sky must be fixed and precise. Flexible roads and flexible skies do not exist. We can change the means of transportation, but we must not divert the roads and turn the sky upside down at will. Back to the optical network itself, the so-called flexible network should be flexible allocation of bandwidth and flexible configuration of services. But these are independent of wavelength. We need to understand that the nature of any business is independent of wavelength, and wavelength is only related to transmission distance.
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