A prolonged network outage in April this year at Canada’s largest mobile communications operator, Rogers Communications, and its subsidiary Fido Solutions, interrupted subscribers’ access to wireless voice, data and internet services across the country including in major urban centres.
Rogers attributed the outage, which downed services for a large proportion of its 10 million subscribers nationwide for up to 26 hours, to issues with a software update on central parts of its network. Although not specifically identified, the company’s public statement points to the seat of the problem being in its core network. In common with many other operators, Rogers is employing network virtualization (NFV) to decouple software from hardware on its network to support the rollout of 5G.
Over the years, outages brought about by problems arising in the core have affected 2G, 3G and 4G networks. With the rollout of 5G, core network functionality is being massively enhanced and “softwarized” as an essential step towards unlocking new business models, monetizing 5G services, and delivering a supreme service experience.
Once a stand-alone, hardware based resource with discrete service functionality and dedicated gateways, core networks in the 5G era will permeate into all areas of the service provider’s management, connectivity and service delivery capabilities and become integral to the creation, proliferation and commercialization of the full range of digital services.
As the core network becomes increasingly virtualized and software-driven, so core technology is being woven into the fabric of the wider network. It is therefore critical that rock-solid reliability and generally good core network “hygiene” are at the heart of operators’ strategies if future problems are to be avoided.
Early 5G network deployments have employed a non-standalone (NSA) architecture requiring only a relatively minor upgrade to the existing 4G core network. As 5G evolves however, and networks move towards standalone architectures, a more major upgrade is necessary with the introduction of a full 5G core. The logical structure of the core network is incorporating developments such as the separation of the control and user planes (CUPS), while physical elements within the core are being virtualized using NFV to provide an all-pervasive, cloud-based software service platform.
This new converged core network will support a range of digital services and applications for consumers and enterprises, including mobile broadband, mission-critical services such as industrial processes, remote surgery and smart vehicles, and massive IoT. It will also address specific challenges including privacy and security, performance and flexibility through innovative, bespoke features such as network slicing, committed bandwidth and SLAs.
Many operators’ plans to create a convergent, cloud-based core network platform are already well-advanced in the expectation that it will not only reduce opex and create a simplified, intelligent and agile 5G core, but that it will provide a platform for the introduction of a cloud-native architecture that will proliferate throughout the rest of the network, and help transform them into fully-digital service providers.
Outages highlight core network vulnerabilities
Outages have been a recurring feature in legacy networks. In recent years, network outages and service degradations have affected several operators around the world, including among others Bouygues, T-Mobile, Vodafone, TIM, O2, and Telcel. The causes of these are various and have included physical threats such as fibre cuts, criminal damage and fire, as well as core network issues.
With downtime ranging from minutes to days, and costing according to one estimate around $20 billion a year, the impact on services and on the operator’s business can be significant. As well as loss of basic voice, data and internet access, critical services such as first responder networks may be affected. In future, a range of industrial applications and mission-critical processes will also rely on 5G networks for continuity and productivity.
In the present pandemic with massively increased home working, home schooling and critical access required to key medical services, the impact and the potential for disruption to businesses may be heightened.
Rogers CTO, Jorge Fernandez, stated in a blog that the root cause of the intermittent wireless service issue experienced by the operator in April was a recent software update relating to its Ericsson-supplied equipment, although details supplied were scant. Whatever the full picture, the outage could be seen as illustrative of the vulnerabilities of an increasingly software-based network architecture to unforeseen problems and disruption.
The widespread use of NFV across the network in order to provide pooled resources and cloudification means that stability and reliability become increasingly critical. Along with a greater degree of integration and aggregation comes more complexity.
Emerging markets benefit from early adopters’ experience
For operators in developing markets this may mean that a cautious approach to core network modernization might be advisable, particularly as this provides an opportunity to benefit from the experiences of early adopters before embarking on major upgrades.
With the level of disruption caused by core network issues potentially being multiplied in a more complex 5G scenario, the impact on services, operations and time to repair can be more uncertain Achieving a smooth migration to the new platforms without service disruption will involve managing growing complexity and addressing issues such as the technology legacy of multi-vendor circuit-switched and packet-switched core environments, and the need for an informed and methodical approach to aspects such as software lifecycle management.
For their part, core network vendors need to address operator concerns and ensure that mature, reliable cloud-based solutions can provide the necessary capabilities to enable a smooth network transformation to 5G. Key to this will be the capacity to identify and isolate the potential causes of outages or service degradation before these become apparent to customers and begin to impact levels of service.
Equipment vendors are already addressing the key challenges arising from core network “softwarization” but greater reliance on software at every level of the core network can render it more vulnerable, and they are under pressure to implement changes such as software updates faster than previously, and without interrupting services.
Rogers' experience suggests that the core network needs to be a focus of attention for the global mobile communications industry. Maintaining and ensuring the integrity of the upgraded core network is clearly critical to service providers’ new role, and to the services and applications that need to be supported. It is also clear that a reliable core network is essential to unlocking new business models, monetizing 5G services, and delivering a supreme service experience.
Julian Bright - Independent Analyst
Julian Bright is an independent analyst covering a range of wireless broadband technologies including 5G. He has over 20 years experience as a commentator and analyst in the telecoms arena, most recently with Omdia (formerly Ovum). Prior to that he spent several years with a major telecoms equipment company working mainly on projects for BT.