About Richard Arthur

Richard has enjoyed a wild ride through more than two and a half decades of the Internet revolution. Currently he has profit and loss responsibility for a set of Fujitsu software solutions focused on service assurance, NFV/SDN, and 5G. His primary task is to steward Fujitsu software solutions to market. Prior to Fujitsu, he held various strategy, leadership, marketing, and technical roles in Hewlett-Packard, Compaq, Digital Equipment Corporation, and Nortel, among others. A popular, experienced speaker and technology blogger, Richard is frequently on the agenda at industry technology conferences. He is also an active participant in the Telemanagement Forum and other industry-standards bodies, serving as a Board Member, Document Editor, and guiding Technical and Marketing Teams. Outside of work, Richard indulges a passion for computer-based composing, music recording, and digital photography. When unplugged, he enjoys outdoor sports such as soccer, downhill skiing, stand-up paddle, running, and cycling.

OSS and Orchestration Challenges in a 5G World

The 5G network is virtualized through a complex interlinking of individual components running as Virtual Network Functions (VNFs), and network slicing. While VNFs have been around for a while, network slicing presents itself as the next step in SDN technology—amounting to full virtualization of the network from radio to core. The separation of the network into VNFs and Network Slicing provides a huge leap forward in network flexibility, but the price of this advancement is that it will make orchestration and management much more complex.

My earlier blog, “A Domain Approach Could Simplify 5G Network Management,” examined the potential benefits of domain-based management as a remedy for the inherent complexity of 5G networks. In this article, I’m looking at the real-world OSS and orchestration challenges we’re encountering as we work with customers towards full 5G roll-out, including the timelines and best practices to prepare the 5G operations toolset.

Breaking Down the Challenges

5G OSS and orchestration present challenges in three primary areas: 

  • Mobile network: Virtualization of the Radio Access Network, the new 5G core, transport architectures built for slicing, and large-scale virtualized infrastructure
  • Software platforms: SDN/NFV management for increasingly prevalent open source in the OSS, as well as for Linux Foundation networking and edge initiatives
  • 5G services: A new, distributed approach to enable management for ultra-reliable, low-latency, and massive machine communication services

The Timing

According to Heavy Reading’s March 2019 survey of 5G operators, almost 80% of them expect to deploy 5G technology in the next two years. At least half expect to start transport upgrades for 5G by the end of 2019. Finally, by 2022, these operators expect to see the arrival of massive machine type communications and network slicing. 

The evolution of OSS and orchestration should focus first on new radio and transport, followed by vRAN, and then on new services and slicing.

Key Functional Areas

Key functional areas within a domain-based management approach include:

  • vRAN and radio management and control
  • Transport network management and control
  • Virtualized infrastructure orchestration and management
  • Core network management
  • End-to-end: inventory, service orchestration, policy management and assurance
  • Network slice management
  • Design, planning and testing

These areas align with the expected rollout of 5G, as shown in the table below:

Enabling Technologies

Enabling technologies we expect to see include the following: which align with the notional rollout of 5G:

  • Linux Foundation networking and edge open source (i.e. ONAP, ODL, Akraino):
  • AI and machine learning
  • O-RAN – Radio intelligence controller and open APIs
  • Virtualized infrastructure management and orchestration: open-source MANO, OpenStack, Kubernetes, Akraino
  • Standards from 5GPP, ETSI and others.

The Linux Foundation provides a useful summary of these inputs in their Open Source Networking Landscape diagram, as reproduced below (Source: Heather Kirksey, VP Linux Foundation):

What’s Next?

The current state of open-source networking technology means that operators must move carefully, since it is not clear which projects will gain stable traction in the market. There’s no guarantee what direction the market will take, and competing projects risk wasting valuable resources. A phased approach is necessary, with transport and requirements specific to 5G NR taking precedence.

AI and machine learning have become critical due to the scale and real-time nature of 5G. Defining AI use cases and using machine learning to tune AI solutions for 5G will be essential, and the 5G core needs to be managed as part of the end-to-end solution, which also includes coordination of network slicing across all parts of the network.

When it comes to the edge of the network, Multi-Access Edge Computing and IoT will bring new requirements for management:

  • Edge management provides low latency 
  • Coordination between IT resources at the edge, and the vRAN and transport networks ensure real-time demands can be met.
  • IoT brings a high volume of devices to the network that require new approaches to bring high volume, energy efficient management.

Conclusion

Each phase of mobile networking across initial roll-outs of 2G, 3G and 4G, introduced OSS and orchestration to manage that specific network’s infrastructure and services. In the past, these deployments often took place after the fact, and were typically built independently for each part of the network. This led to the creation of OSS silos for each part of the network, with little correlation between them. This process won’t work for the 5G network.

5G needs a new way of thinking about end-to-end management. Openness, virtualized infrastructure, real-time services, and the volume of devices and cell sites all play a role. A careful, planned, and timely rollout out is needed for OSS and orchestration. Only then can operators deliver a successful 5G experience.

A Domain Approach Could Simplify 5G Network Management

With the advent of 5G, a much more highly virtualized and dense mobile network infrastructure will place greater demands on management.  5G virtualization presents new challenges, both through individual components running as Virtual Network Functions (VNFs) and through network slicing, chiefly because these factors result in complex networks and consequently, much more complex network management.

Work is underway among the industry groups charged with developing and ratifying standards for 5G implementation. However, the current visions for slice management run a high risk of making network management so complex that it will significantly impact 5G roll-out and flexibility. The burdens of complexity will likely drive service providers to avoid the problem by adopting single-vendor network solutions. This will impact openness, and reduced commitment to openness carries a high price.

But what if there were an approach that simplifies slice management and allows service providers to bring 5G quickly to market.  Such an approach could base network management on a simple technology domain-based model, using standard interfaces per-domain to address 5G management and then evolving this design after initial deployment.

Engineering principles tell us the way to solve a complex problem is to break it down into simpler smaller problems. For 5G this means breaking the network into domains that can be managed individually but also linked to each other for capacity planning, service management, correlation, etc. A great deal of work is going into slice management for 5G, but it is also essential to think about the big picture and consider the entire approach for a fully manageable, easily implementable 5G network.

Figure 1: The 5G domains we expect to manage 

By breaking the problem down to domains, we can rely on each domain to understand the best way to provide resources for each 5G service class. These domains could also own the job of keeping service classes separate, so as to provide each as a separate network slice.  It would then be the job of multi-domain orchestration to manage the combined resources to provide the end-to-end network and make it visible to the service layer.

The domains shown in Figure 1, and their interfaces are as follows:

  • User Domain: The 5G user equipment, such as a smartphone, set-top box, PC, or IoT device. User equipment management standards will be part of the base specifications for 5G.
  • Virtualized Radio Access: Contains the remote radio, distributed unit and central unit, and where possible, runs as VNFs on commercial off-the-shelf (COTS) compute, storage and inter-networking provided by the virtualized infrastructure domain. The ORAN (Open Radio Access Network) Alliance is standardizing management interfaces for the 5G RAN as well as for interworking interfaces in the network.
  • Transport Domain: The transport domain is potentially split beyond what is in 4G. It contains fronthaul, midhaul, and backhaul elements, and will typically be an Ethernet over optical infrastructure. This domain may contain a cloud control layer based on virtualized compute. Existing transport interfaces across IP, Ethernet and optical layers are usable here including: Transport API (TAPI), Metro Ethernet Forum lifecycle orchestration (MEF LSO), and TM Forum interfaces. Open-source tools like OpenDaylight will be relevant to building interoperable controllers in this domain.
  • 5G Core: The core 5G network functions for functions such as authentication, access and mobility management and policy control. The 5G Core runs as VNFs on COTS provided by the virtualized infrastructure domain. 5G Core domain functions will have management interfaces defined per-function as part of the base 5G specifications.
  • 5G Services Domain: The 5G services domain understands the business logic and service class requirements for 5G services. Various standards and open source technologies may be applicable such as TM Forum and Open Network Automation Platform (ONAP), as well as work in the 5G Public Private Partnership (5G PPP) and other bodies.
  • Virtualized Infrastructure Domain: This domain includes the COTS infrastructure and the software stack for virtualization, including technologies and APIs from OpenStack, Kubernetes, and the Cloud Native Computing foundation. Telecom-specific software such as ONAP and Open Source Mano (OSM) can be applied.

Figure 2: A domain management approach to the complex 5G infrastructure 

In the scenario represented by Figure 2, each domain understands how to deliver its own appropriate set of network slices. This set of slices is then brought together by the multidomain orchestration layer to deliver an end-to-end network. The service layer can then request an end-to-end network from the orchestration layer that specifies the service class required.

Clearly, there will be cases where one domain needs visibility or control of an adjacent domain to provide the service level required. The multidomain orchestration layer could provide a dependency model that ensures such dependencies between domains. Ultimately some form of peer interworking between domains will be needed.

Looking at the long term, one desired goal may be to reduce the overall number of domains by combining management to get better capacity utilization and control over the infrastructure. However, separation allows for smoother initial roll-outs while retaining the openness desired by network operators. Another goal will be to begin to implement the full network slicing models envisioned by groups like 5G PPP and European Telecommunications Standards Institute (ETSI) as the 5G network matures.

The simplicity of a technology domain-based approach in early roll-outs of 5G will ensure that operators can mix and match technologies and avoid vendor lock-in, while still providing the services needed by customers and fulfilling the overall potential of the 5G network.