Deutsche Telekom’s VP of core network development, Franz Seiser, heads up the telco’s multiyear program to implement a 5G, cloud-native core. This will run in parallel with converting 900 of its telco locations in Germany into edge cloud centers, or cloudlets, which could host distributed core as well as other virtual network functions (VNFs) for DT’s own network, or to support customer or partner services.
Seiser is keen to use open source technologies wherever possible, to ensure interoperability, reduce time to market, and to access the widest base of innovation in equipment and developers. However, he acknowledges open source may not, in the early years, save deployment cost because of the need for integration, and work to ensure the systems are fully carrier-grade. Therefore, choosing the right open source technologies is vital.
“The challenge is to figure out the right ingredients but also combine them in the right way … You can have the best ingredients and not know how to cook properly,” he said.
After dialling down the pace of a big-bang cloud initiative called pan-net, DT has been steadily moving network functions into the cloud over the course of the past two years, and some are supporting some commercial services already. Other priorities are to move towards what DT has called “brutal automation” in the network, and Seiser said the biggest gaps lie in orchestration of large numbers of multivendor VNFs, and in changing the internal culture of a workforce unaccustomed to the cloud.
The other big challenge, as echoed by BT and many others, is to optimize open and cloud-based network software to make its performance equal to, or better than, that of a non-virtualized, appliance platform. This currently makes the deployment of vanilla open source systems more expensive than of old-style, pre-optimized functions.
In addition, DT is also having to convert its early virtualization efforts, based on virtual machines, to support the more agile and programmable microservices environment. But that raises problems of its own – notably the complexity of orchestrating huge numbers of microservices, a challenge which makes full automation absolutely critical. And despite its attractions, open source can add to the risk and the complexity, compared to relying on a single trusted supplier to deliver the whole cloud-native platform.
Seiser said DT has been evaluating several suppliers in terms of their ability to combine open source technologies to build a cloud-native 5G core. “The differences were rather big,” he said. “Some were close to and others were quite far away from our definition of cloud-native.” That highlights yet another risk for operators embarking on the road to 5G core – the immaturity of all the solutions, and the conflicting claims and definitions made by the vendors for their ‘cloud-native’ systems.
A common approach is needed so that all operators can address complexity in the same way, otherwise “the software guys will charge like crazy,” Seiser said. That will also mean making choices between the many open source options on the market and unifying around them.
DT has been working with Samsung on its future migration to 5G Standalone with the 5G core, and also with a wide range of suppliers on its broader cloud-native platform. These include Mavenir on tests of a containerized 5G core, VMware, Cohere Technologies and Dell EMC.