Some large operators are starting to set out clear roadmaps to a cloud-native, container-based architecture for their 5G core, though the cloud-native RAN is some way behind, possibly by several years in terms of large-scale, macro network deployments. Vendors like Nokia are offering cloud-native vRAN systems, and also supporting open interfaces such as O-RAN, but most operators indicate they will initially trial such technology in greenfield, secondary or localized networks, rather than risk any performance trade-offs in the main network at this early stage.
It is different for fully greenfield MNOs, of course. Rakuten Mobile, Dish Network and others have the luxury of not having legacy physical networks to integrate, sunset or depreciate. But even for these new players, the technology was not ready for fully cloud-native deployment from day one. Much was made of Rakuten having the first end-to-end cloud-native telecoms network, and it may still claim that crown, but only when it has deployed the next generation of its software. In the vRAN, in particular, it rolled out its first network based on virtual machines, although it is now working with its main vRAN software supplier, Altiostar, on a containerized upgrade.
Marisa Viveros, VP of strategy for telecommunications, media and entertainment at IBM, told LightReading: “If you are going to have these super-fast networks you want applications to be equally fast. You want the applications moving and you want workloads to be placed where it makes the most sense … Containers have less overhead and require less payloads on the system resources than virtualized machines.” They are also more portable between different hardware and operating systems.
Tareq Amin, Rakuten’s high profile CTO, agrees and recently set out the plan to phase out the current 4G core and introduce a single converged, cloud-native core for 4G and for 5G Standalone, within 14-16 months. The initial evolved packet core, developed with Cisco and other partners, is based on virtual network functions (VNFs) rather than cloud-native functions (CNFs) alone. Rakuten is developing its cloud-native 5G core with NEC (this will also be offered to other operators as part of Rakuten’s plan to package up and license its mobile platform and establish a global marketplace to expand it).
Amin said: “What we have learnt from our first phase in Rakuten is that going from proprietary to virtual was a maze. We have deployed 198 unique VNFs, but there are a lot of things that are missing. As elegant as this architecture that we have done is, we are not completely satisfied. We want to get to a state where we can truly have elasticity, let the containers manage themselves and scale in and out based on demand.”
He continued: “In the virtual machine world it’s not as easy, simple and orchestrated as you might want to believe. It has been a difficult, super difficult, journey because with these VNFs we have to spend significant energy to bring common orchestration, and we are still nowhere close to where we need it to be.”
The US and Chinese telcos, increasingly getting caught up in their respective governments’ ‘5G race’, are also intensifying their efforts to go cloud-native. Verizon announced a year ago that it was working on a proof of concept (PoC) of a containerized core running in a live network. And at the recent Red Hat Summit virtual conference, Srini Kalapala, VP of technology and supplier strategy at Verizon, provided an update, saying the operator is working with Red Hat to deploy a truly cloud-native stack for 5G.
“From the RAN to the core it will be built on a cloud-native stack,” Kalapala said, but he also highlighted the huge effort that is needed for this migration, at least in these early stages when there are no ‘off-the-shelf’ solutions and significant integration work is required, whether that is done largely inhouse, as at Rakuten, or by vendors or independent system integrators. Kalapala said Verizon began its network virtualization journey back in 2015. “Telcos are following the webscale companies and we are a little behind,” he said.
Verizon has completed the first data session on its new 5G SA core and plans to start shifting mobile traffic over by the end of 2020, with full commercialization in 2021.
Last week, Verizon’s VP of planning, Bill Stone, told the press: “By building this 5G core with cloud-native containerized architecture, we will be able to achieve new levels of operational automation, flexibility and adaptability.”
“The 5G standalone core is critical for unleashing the most advanced benefits of 5G technology including remarkable levels of programmability to manage the advanced solutions and exponential traffic that 5G will bring,” he added.
Among the capabilities Verizon expects to enable with 5G SA are network slicing, real time RAN resource management, advanced network analytics including AI/ML, and a more scalable and cost-efficient network architecture.
In July, Verizon first talked about its core network trial with Ericsson, and provided a roadmap on its five-year program of implementing virtualization. The first stage of the trial focused on a 4G core – some operators are developing enhanced 4G EPC first, to get comfortable with cloud-native technology, before moving to the full SA architecture. Verizon’s container-based, cloud-native 4G evolved packet core (EPC) will be the basis of the 5G platform, said Akhil Gokul, head of core and cloud in the CTO office of Ericsson’s Verizon customer unit.
Santiago Rodriguez, head of 5G Standalone packet core and communication services for Ericsson North America, said last year: “What we’re doing here is combining network functions for 5G SA with functions for NSA into the same platform: all cloud-native, all operating in the same way. So this will make it easier for operators to jump from NSA to SA.”
Verizon said it will also examine the potential to move legacy LTE core to the cloud “opportunistically and selectively”. Ericsson believes transitions like Verizon’s will reduce the cost of network software upgrades by 90% for MNOs in future, and cut hardware infrastructure costs by 90%.
That should help with network robustness, since software upgrades will not require parts of the network to be taken down. “It’s in our DNA to operate very reliable networks,” said Stone.
The trial, conducted in Hillsboro, Oregon, involved the Mobility Manager Entity (MME) virtual network function (VNF), enabled by Ericsson’s Packet Core Controller. It leveraged key features of a container approach, such as docker images and helm charts, to support a constant stream of software updates (about one every two weeks, says Ericsson).
Stone was looking beyond the core, saying: “We see opportunities to use and leverage cloud-native container-based technology not just in the core network, which we’re doing here with this proof-of-concept trial, but we see opportunities to take advantage of that technology as we virtualize network functions that will run at the edge of the network as well.”
The RAN will be in his sights, and Verizon has already engaged in tests of vRAN. In May it demonstrated a fully virtualized RAN baseband, enabling edge computing, in its network in California, working with Intel and Nokia. An earlier trial, held in January in Houston, Texas, used MEC equipment and software in a 5G testbed and claimed to have cut latency in half.
“Now that we can separate the software from the underlying hardware, it gives us more flexibility, and it’s important because it reduces latency. We also believe over time this is going to become a more efficient and cost-effective configuration,” Stone said at the time. “The two things combined, California and Houston, are where we plan to go in the future. As we move forward with 5G deployment, it’s a critical part of our strategy to deploy these general purpose platforms toward the edge and take advantage of virtualizing more of the baseband functions while also preparing to host additional applications.”
The trial used Nokia’s AirScale All-in-Cloud Base Station architecture, Intel Xeon Scalable processor-based servers and the Intel FlexRAN reference architecture, which supports the RAN stack running on servers.
Verizon is working with other vendors including Ericsson and Samsung, and will conduct more vRAN trials this year. “As we continue to proceed with 5G and modernizing the network, all of the new network functions that are being put in place will be cloud-native and fully virtualized,” Stone said. “This is table stakes.”
T-Mobile USA and AT&T also plan to start the migration to 5G NR Standalone (SA) and the 5G core later this year, with full commercialization expected in 2021. TMO has chosen Cisco and Nokia as its 5G core vendors, while the other telcos have not disclosed their partners yet. Verizon said it has “several infrastructure vendors on the core side all working together for the new core”.
ONAP’s Frankfurt release:
The Linux Foundation’s Open Networking Automation Platform (ONAP) has announced its sixth release of specifications, called Frankfurt. This includes a blueprint for operators to scale their 5G networks and focuses on cloud-native network functions and containerized functions.
The Frankfurt release also introduces end-to-end network slicing with methods to model and orchestrate a network slice across 5G RAN, core and transport elements.
Operators including China Mobile, AT&T, Verizon, Orange and others are in various stages of implementing Frankfurt.