From 10G to 200G coherent DWDM waves

The demand for more bandwidth increases is known to the reader. The reader also knows that the connectivity between, for example, data centers and internet nodes has long been based on fiber connections. Where at the beginning of this century 1GB was considered sufficient, we are now used to 10GB connections, and more and more 100GB connections are being used. 100GB is of course not the highest possible, as with fiber optic 200GB and more is also possible.

A year and a half ago, Serverius decided that the network needed an upgrade to keep track of the growth in customers and traffic. The starting point was the deployment of coherent DWDM, a technique that allows the capacity to increase existing fiber optic channels. Normally a higher light intensity is being used, and for coherent DWDM the phase and polarization will be adjusted. This technique is not new. There were already scientific papers more than ten years ago that described this combination. They experimented this combination in small-scale laboratory setups, but that’s not where it stopped. The demand for higher capacity was still do-able with the existing resources. But for the last few years, due to the arrival of really large data streams by CDN’s, video, cloud and similar, the interest in coherent DWDM has increased. This leads to the demand of market parties such as Serverius.

“We spend a lot of attention to redundancy because it is the base of our services

Sergey Petukhin
Head connectivity infrastructure at Serverius

The Serverius case

Sergey Petukhin is the first to explain that in line with the Serverius philosophy, the safety and availability comes first. “We spend a lot of attention to redundancy. We do that because it is the base of our service and because our customers expect that from us”. He mentioned it because with that the architecture of the Serverius network becomes clear. “For us, redundancy means that we connect the two data centers with the two separate glass fibers of two different suppliers with other pops”. Serverius is still going a step further, including the equipment that is used for coherent DWDM from two different suppliers, in this case Coriant and MRV/ADVA.

Petukhin then goes into the bandwidth: “There are several possibilities and speeds. Currently 10GB is very much in use and that also has to do with the available hardware. Some parties will bundle 10GB connections to higher capacity, but that is not optimal.

You’re there with overhead and it is particularly not efficient on other points either. The step to 100GB is therefore more logical. “100GB sounds like a good step, but with coherent DWDM the capacity to upgrade a 10GB connection to 200GB is possible. You can still continue and use the existing infrastructure, only the optical transceivers will need to be replaced and the channel must be adjusted to be able to deliver 20 times more bandwidth”.

Serverius was one of the first, if not the first, in the Netherlands that started working with this technique. Although other parties started using the coherent DWDM, there is still a big difference. The technique is namely designed with the traffic between datacenters and pops mutually. That is also the case for most places that is being used. Serverius delivers it also as a service to customers and that is what makes it a special proposition.

Petukhin: “The nice thing about this technique is that you have one permanent 10GB connection which you can tune up with a couple of simple actions and the capacity can reach up to 200GB. That is of course a perfect solution for customers and partners who have to deal with traffic boosts.”

Since the beginning of April, the coherent DWDM has been full in use at Serverius. Partners who use this option are for example the IXs which Serverius works with together. In addition, it is for customers who consider the Serverius network a serious option and connect with their own locations.

The ones that know Serverius are familiar that it is one organization that develops products themselves and perfecting them are listed high on their list. In case of coherent DWDM, there has been a lot of intensive contact with Coriant and MRV/ADVA. The cooperation with this two parties was, in the words of Petukhin, very educational. On the question if he and his colleagues also tested the products themselves, he replied laughing: “Of course we analyzed the software thoroughly, but we hardly found bugs with possible impact on availability or quality of the service.”


The greatest benefits of coherent DWDM are certainly the higher capacity and the possibility of continuing to use the existing infra . But these are certainly not the only plus points. Petukhin calls the increased intelligence as a very important plus. “Coherent DWDM is supplied with extensive tooling that allows all facets of the connection to be monitored”. That is really one decent progress. In addition being able to adjust for example the speed is something that goes much easier. It is a software-based intervention. Because there is no question anymore for multiple channels and capacity bottlenecks, the quality of the connectivity  is much better. That makes a difference again in preventing and remedying of incidents. Petukhin: “We notice at Serverius we save time through this technique. Our partners and customers who use this technique will also experience this too.”.

Serverius organizes meetings several times per year where the technique, such as coherent DWDM, is presented and where the content is technically explained. For those who can not wait and want to know what Serverius can mean for his organization, can contact us via the details below.

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