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Do you need to be worried about the performance of your 5G core user plane?

Do you need to be worried about the performance of your 5G core user plane?

Classifying myself as a bit of an old-timer within the telecoms industry I’ve seen a considerable amount of change to mobile core networks over the years. It doesn’t seem that long ago when purpose-built hardware designed to perform the function of a core network was in use. In more recent times cloud-transformation of the core network has started. Initially the core network was virtualized, which at the time seemed revolutionary but in reality, was nothing more than moving the core software to run on servers.

As the cloud transformation journey continued things eventually became cloudified or cloud-native. This included separating the core business logic from the storing of subscriber state: the so-called software modularity and state-efficient phases. This initially gave the ability to use network function virtualization environments with the core being run inside virtual machines, with a continued migration to other environments such as containers.

The word containers gets people excited. It’s seen as the saviour of ever-increasing complexity within the core as well as delivering the efficiency needed to drive down costs. Automation is being introduced to improve the reliability and speed of deployment. The industry seems to have gone gaga for cloud-native, often tagged as the pre-requisite for the core to be 5G ready.

However, throughout this transformation journey and even now, the issue of performance has been somewhat overlooked. Having arrived at a cloud-native core, performance concerns have typically been addressed with the elasticity characteristics of the cloud. If you need more horsepower, then just spin-up more servers. That is all very well, but ultimately comes at a cost, in terms of footprint, power and networking complexity.

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A neglected part of the mobile core network when thinking about performance is the user plane. It’s sat there just fine for many years, processing data rates of a few 100’s kilobits and then a few hundred megabits. Not even breaking a sweat. But data rates are accelerating in ways old-timers like me have never seen before, moving towards multi-gigabit from a single device. The mobile core network user plane would be right to look worried.

This performance headache is rooted in mobile core network architecture and design. Up until now, the user plane has coped just fine as most of the network load is still at relatively low levels and can be adequately distributed. But the performance issue will raise its head as we move into the 5G era, primarily as devices can support massive high throughputs, and the user plane function is required to become a high-performance IP forwarding engine.

Let me go back to mobile core network architecture and design to explain the problem. The performance of the user plane in some mobile core network architectures is dependent on the number of available virtual CPU cores, how user plane flows are allocated to a virtual CPU resource and the existing load being handled at the time. When traffic from a high throughput device needs to be processed, the traffic flow is allocated to an available virtual CPU resource. The challenge is when all the traffic flows assigned to a virtual CPU resource exceed the throughput capabilities of that vCPU resource. When this occurs the IP and other networking layers will adjust the throughput characteristics of the individual flows. This has the effect of negatively adjusting the applications being delivered and hence the experience of the user of the high throughput device. If we think about 5G, one of the benefits we are looking for is not only expanded capacity but an enhanced user experience. Therefore, decisions made in the mobile core user plane function software around its architecture and implementation has the potential to impact the overall 5G user experience.

Nokia is an industry leader in high performance IP routing, developing its own highly optimized packet processing silicon that is arguably many years ahead of our nearest competitors. Nokia has developed its IP forwarding software embedded in its SROS operating system that can leverage capabilities of multiple vCPUs to maintain its performance under high traffic load. With the emergence of the cloud and other industry initiatives, Nokia has taken this industry knowledge to develop its virtual forwarding plane for deployment on high performance or generic compute to deliver significantly better performance compared to other vendors and/or generic open-source user plane implementations. This virtual forwarding plane is used in the Cloud Packet Core’s user plane function.


Nokia’s virtual forwarding plane supports high throughput 5G devices without overloading the vCPU resources within the user plane, thus removing erratic behaviour based on traffic load which could negatively impact the end user’s experience. Given the architecture and capabilities of the virtual forwarding plane software, this enables the Nokia virtual user plane function to efficiently leverage the continued increase in the number of vCPU’s contained in processor silicon to deliver predictable high-performance virtual user planes.

A further biproduct of leveraging the high-performance SROS software used in Nokia’s industry leading IP router portfolio is the ability to embed integrated GiLAN functions (Firewall, CGNAT, TCP-O, DPI/URL filtering) in the same user plane function instance. These integrated GiLAN functions will be key in delivering low latencies, while simplifying and reducing the cost, footprint and networking of user plane function deployments.

As service providers accelerate the pace of their 5G developments with the objective to use 5G to support a wide range of services with diverse and demanding performance requirements and look to insert 5G into new industrial automation value chain opportunities, they cannot afford to overlook the issue of user plane performance. With our IP routing heritage, our continued innovation and investment into mobile core networks, along with our knowledge and services expertise re-assures service providers that Nokia can evolve their core networks with confidence and enable them to profit from these new opportunities.

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