Recently, LightCounting, a leading optical communications market research company, updated its industrial research report on IP over DWDM, incorporating the latest insights from MWC 2023 and OFC 2023. After in-depth interviews with many industry insiders spanning carriers, cloud service providers, device vendors, and optical device suppliers, LightCounting concluded that the IP over DWDM solution based on 400ZR/ZR+ pluggable optical modules cannot be deployed on carrier networks on a large scale. This is because the IP over DWDM solution is not able to save costs as effectively as the IP+DWDM solution, and in fact increases the complexity of operation. To conclude, IP+DWDM is a better option as it can not only support new applications in the future, but also reduce overall operational cost of the networks.
1. Telefonica: Compared with the IP+DWDM solution, IP over DWDM is less effective at saving costs, and in fact increases the complexity of operations
Oscar Gonzalez de Dios from Telefonica shared his predictions and opinions about the future of the IP over DWDM solution based on its deployment in the industry over the past decade. He believes that, despite having been put into commercial use for more than ten years, the IP over DWDM solution has not been used to a great extent on telecom carrier networks. This is because the solution is more suitable for P2P data center interconnect scenarios of cloud service providers, and creates more issues when applied to carrier networks. Although 400G ZR/ZR+ optical modules can solve some issues, the following two most critical issues remain:
- Operation complexity issue: IP routers and DWDM transmission devices need to be operated by different management teams and use different software management systems.
- Rate evolution issue: A DWDM transmission device always has a higher data transmission rate of optical ports than an IP router.
Oscar Gonzalez de Dios also introduced Telefonica's progress in controlling IP routers and DWDM transmission devices with unified software, and predicted that the deployment of a multi-layer software definition network (SDN) controller can be a solution. Optical Internet Forum (OIF) is running related projects based on this idea, while Nokia also launched IP/DWDM unified management software at MWC 2023.
In addition, through conversations with LightCounting at the Optical Fiber Communication Conference (OFC), Cisco revealed that the IP over DWDM solution has been deployed solely in small Internet Service Providers (ISPs), and is used mainly on simple networks. The vendor revealed that the solution cannot be deployed on a large scale on complicated networks of giant telecom carriers.
2. Google: Although 400G ZR has been used in some metro short-distance scenarios, gray optical module interconnection can be reintroduced in the future
Tad Hofmeister from Google noted that the company has successfully deployed 400 ZR modules on Layer 3 switches, but such deployment is limited to only a few metro short-distance interconnection scenarios. Google plans to deploy 800 ZR modules next, and in future expects to deploy 1.6T pluggable modules. But if the modules consume too much energy, Google will consider other solutions. For example, Google may consider gray optical module interconnection, and even use optical cable and co-packaged optics (CPO) to reduce costs and power consumption.
A very important reason is that over the past decade or so, the cost of gray optical modules has declined dramatically: Ten years ago, the price of a 100G CFP LR4 (10 km) optical module was about US$5000; today, the price of an optical module based on QSFP 28 is lower than US$300. With the sales volume of such optical modules exceeding 1,000,000 in 2022, the price of gray optical modules will keep falling to levels beyond what was imaginable ten years ago. Another case is 400G FR4 (2 km) optical modules: Because of the huge shipments in 2022, the price has been far lower than that of 400G LR4 optical modules (10 km).
3. IP+DWDM split architecture can bring more flexibility, support new applications in the future, and reduce overall network operational cost
According to LightCounting research, carriers prefer the IP+DWDM solution to IP over DWDM because of the flexibility brought by the split architecture of DWDM transmission devices and IP routers. The IP+DWDM solution can use different data transmission rates on IP routers and DWDM transmission devices, overcoming the problem that DWDM transmission devices have a higher optical port rate than IP routers. Such an architecture also supports flexible deployment of DWDM optical ports of different rates based on the transmission distance and capacity requirements of specific links on networks. In short, the solution is more balanced than IP over DWDM.
Dr. Maxim Kushnerov from Huawei analyzed the Total Cost of Ownership (TCO) advantages of the IP+DWDM solution at OFC 2023, which is shown in the following figure. His analysis includes both the cost of pluggable optical modules and the cost of IP and DWDM device boards.
From these analysis results, it is clear that IP over DWDM is not effective at saving costs on gray optical modules, and in fact greatly increases the complexity of network operation. This is also the most tricky problem for giant telecom carriers. According to LightCounting, IP+DWDM offers a better option for carriers, owing to its support for all kinds of new network applications in the future, as well as its savings on overall network operational cost.
Source: https://www.lightcounting.com/research-note/april-2023-debate-on-ip-and-dwdm-continued-in-early-2023
