Extreme Networks Fabric core replacement delivered under maximum operational pressure
Public Health England (now the UK Health Security Agency)
“The best outcome was that nothing happened. The network just carried on.”
At a glance
Primary outcome: The core of the network was replaced during the COVID crisis while the organisation was under intense national scrutiny, and operations remained protected throughout.
What we delivered: A new Extreme Networks Fabric core, built and cut over in a controlled way so critical services kept running.
Notable outcome: A core transition measured in seconds, delivered so cleanly it was if it never happened.
Why this mattered
This was not a routine refresh in a quiet window. At the time, Public Health England sat at the centre of the UK’s pandemic response. The network was a dependency for everything, data, communications, and the day to day work that needed to keep moving.
At the same time, the existing core had reached end of life. Replacement was not optional. Under the pressures being placed on the organisation, the need for a fast, secure and reliable network only increased, so the risk of leaving ageing core equipment in place became harder to justify than the risk of changing it.
That is the frame for this project. Replace the core, the heart of the network, in the middle of the crisis, with the full weight of national attention on the organisation, and do it without disruption. PHE needed a partner who could plan carefully, execute calmly, and not fail.
What Panacea delivered
1) A Fabric-based core designed for resilience and service separation
Panacea replaced the core using Extreme Networks Fabric Connect. Fabric Connect is built on Shortest Path Bridging (SPBM, IEEE 802.1aq), creating a loop-free fabric that supports fast convergence and predictable forwarding behaviour.
The design focused on doing the fundamentals exceptionally well:
- High availability at the core, with resilient paths through the fabric so single component failures are tolerated cleanly.
- Service separation using Fabric services (for example I-SID based service identifiers), so segmentation scales without fragile VLAN sprawl.
- A core architecture that remains stable during change, because the control plane is designed to converge quickly and consistently.
2) A cutover plan built around one priority, nothing breaks
Replacing a core is rarely a single moment, not if you want to keep risk under control. The approach was to build the new core in parallel, validate behaviour, then migrate services in deliberate, reversible steps.
The cutover methodology centred on:
- Parallel build and validation so the new core could be proven without disturbing production traffic.
- Phased migrations with clear checkpoints, keeping each step small enough to troubleshoot quickly and roll back if needed.
- Tight change control, with explicit sequencing to minimise ambiguity during fault isolation and to keep impact contained.
3) Maximum accountability delivery under the hardest conditions
The operational context left no room for improvisation. The way this project succeeded was not by taking risks, but by removing them. Detailed planning, careful organisation, and disciplined execution were treated as non-negotiable.
This is where Panacea’s ethos shows up. You do the work that reduces uncertainty before anyone touches production, and you own the outcome when the stakes are highest.
The results (Panacea outcomes)
- The network core was replaced during the height of the COVID response, without disrupting the organisation’s ability to operate.
- Downtime was measured in seconds, and the change was so understated it went unnoticed.
- End of life risk at the centre of the network was removed, restoring confidence in stability and supportability.
- A resilient fabric core now provides a clean foundation for future growth, segmentation and operational change.
About Panacea
Panacea designs and delivers Extreme Networks solutions for organisations that cannot afford disruption. The focus is on careful planning, controlled delivery, and resilient architectures that do their job quietly, even when the pressure is at its peak.
About the customer (Public Health England, now UKHSA)
Public Health England was the UK’s public health body at the time of this work, leading vital activities during the COVID-19 pandemic. It later became the UK Health Security Agency.
About the technology partner (Extreme Networks)
The solution uses Extreme Networks Fabric Connect, a fabric architecture based on SPBM (IEEE 802.1aq) that supports resilient forwarding and service-based segmentation. It is designed to simplify core operations and deliver predictable behaviour during change.
