First Deployments of IP over DWDM in Europe: The First and the Last?
The evolution of DWDM transport equipment from proprietary “black box” systems to all-open “white boxes” has taken a detour along the scenic route, (as illustrated in Figure 1).
The priorities of service providers attending NGON 2022 (the Next Generation Optical Networks conference) were very colorful, with automation and all-optical networks at the top of the event agenda. Service providers still largely count on their trusted suppliers to develop equipment and software they need, rather than relying on white box solutions. The advent of open line systems, pluggable optics and software APIs has made the market a bit more competitive, and it seems to be good enough for now.
Progress in network automation is discussed in our report Telecom Network Transformation, released at the end of June 2022, which captures the latest announcements from NGON 2022.
IP over DWDM was debated at the event. Colt reported its first deployments of 400ZR and ZR+ optics in their IP network in Europe and received the Most Innovative Service Provider award at the show. The use of IP of DWDM was not the only innovation at Colt, but it is certainly the most unique. Colt operates networks in 50 metro areas and interconnects more than 900 data centers. The company can be categorized as a wholesale service provider since it offers optical transport as a service to cloud companies and enterprises. Many of these customers are asking for 100GbE and 400GbE lines and it makes a lot of sense for Colt to add DWDM optics directly on the routers: the network is simple, and the distances are relatively short, so the 400ZR/ZR+ combination is a perfect match. Each new DWDM port is installed directly into a router, as customers order more bandwidth, and service is delivered over the IP layer. Having a separate optical layer would make the transaction less “transparent”.
Figure 2 illustrates where 400ZR+ and 400ZR are deployed on Colt’s IP network. The majority of connections use 400ZR+ transceivers, supporting connections ranging from 270 km to 464 km. 400ZR and 400LR are used only within the metro areas. Non-pluggable 400G optics is used for connections longer than 600 km.
There will be other cases benefiting from IP over DWDM, but it is unlikely to emerge as a mainstream solution among service providers. At least not in Europe, where service providers plan to maintain separate IP and optical layers in their networks.
BT presented its analysis for the cost of IP over DWDM in several deployment scenarios, shown in Figure 3. Cases A and B represent the relative cost of deploying 400ZR (A) and 400ZR+ (B). Costs start low, but grow faster as more channels are added to routers, in comparison with a network incorporating ROADMs for optical by-pass. BT’s study results were first presented at ECOC 2020 but have not been updated since then, reflecting a lack of interest in this approach.
The combination of IP over DWDM ad a ROADM-based optical network offers lower cost than pure IP over DWDM, but controlling such a network will be challenging. As illustrated in Figure 4, such a network will require an “end-to-end orchestrator” to manage the IP and optical layers. BT is clearly not very enthusiastic about the prospects for IP over DWDM.
Orange is also skeptical of IP over DWDM. The flexibility enabled by having separate optical transport equipment is more important because their network is complex and includes a variety of data rates. Orange has not shared details of its network designs, but OTE – an incumbent optical network operator in Greece, presented data on the mix of data rates. Deployments of 10G stopped in 2020-2021, but installation of 100G and 200G continued to ramp up despite the availability of 400G.
Ciena, Huawei, Infinera, Nokia, and ZTE all presented progress with deployments of 800G DWDM systems and the development of even higher data rate solutions. None of these new solutions will be compatible with 400G IP over DWDM.
This is one of the key concerns for service providers as they plan for the future.
The bottom line
IP over DWDM will find applications in enterprise and DCI networks, but telecom service providers in Europe are unlikely to deploy it.
LightCounting will continue research on this topic by interviewing cloud companies and service providers in China, Japan, and North America. We will report our findings in a new report entitled Evolution of DWDM Networks, scheduled for publication in October 2022.
Disclaimer: Any views and/or opinions expressed in this post by individual authors or contributors are their personal views and/or opinions and do not necessarily reflect the views and/or opinions of Huawei Technologies.