Location
London

Hours
Full Time

Salary
Competitive, commensurate with experience

About the Role
Fuse Energy is an energy startup on a mission to make energy abundant and affordable, fast. We combine first-principles thinking with cutting-edge technology to build a radically better energy system. Having raised over $200M from top-tier investors, we are building a fully integrated energy company developing solar, batteries, hardware, grid infrastructure, real-time power trading, AI applications, and distributed energy installations. By selling directly to consumers, we cut out the middleman, lower costs, and pass savings on to customers.

As an HPC Network Engineer, you will design, deploy, and operate the network fabric for our multi-tenant AI cluster. This includes the high-performance compute and storage fabrics carrying RDMA traffic between GPUs, tenant-facing and management networks, firewalling and tenant isolation, and the out-of-band infrastructure ensuring recoverability. Beyond the data centre, you will own the office network and act as the networking authority for the company, owning the fabric from architecture through day-2 operations.

Your responsibilities will include designing and operating lossless, RDMA-capable fabrics (e.g. RoCEv2, InfiniBand) for GPU compute and storage traffic with QoS, congestion control, and buffer tuning at scale; building and managing leaf-spine data centre fabrics with routed underlay and overlay design (BGP, EVPN/VXLAN); implementing and maintaining per-tenant network isolation; automating network provisioning and validation using tools like Ansible and Python; building telemetry and observability with dashboards and alerting; troubleshooting performance issues end to end; operating out-of-band management networks; supporting tenant onboarding including segmentation, addressing, bandwidth guarantees, and capacity planning; writing clear design documentation; maintaining the office network infrastructure including wired, wireless, firewalling, VPN, and office-to-data-centre connectivity; and upskilling colleagues through documentation and pairing.

Experience
- 5+ years as a network engineer operating production data centre networks
- Strong dynamic routing experience, particularly BGP, plus overlay/encapsulation design and troubleshooting such as EVPN/VXLAN
- Hands-on experience with leaf-spine / Clos fabric design and operation
- Practical RDMA fabric experience: lossless Ethernet (RoCEv2 with PFC/ECN/DCQCN tuning) or InfiniBand, understanding the importance of lossless behaviour for GPU workloads
- Experience with modern data centre network operating systems and Linux networking stack beyond vendor CLI
- Network automation as a working practice: scripting (Python), configuration management (Ansible), config generation from source of truth, version-controlled changes
- Solid Linux administration fundamentals with ability to debug from host and switch side
- Experience with network telemetry and monitoring tools such as Prometheus/Grafana, sFlow/IPFIX, streaming telemetry
- Experience running corporate/campus networks including wired and wireless, switching, NAC/802.1X, VPN and remote access

About you
- Clear communicator who enjoys teaching and upskilling colleagues
- Proactive, detail-oriented, and able to work independently and collaboratively
- Passionate about building scalable, reliable, and observable network infrastructure

Qualifications
Bonus qualifications include:
- GPU cluster networking experience (NVIDIA Spectrum-X or Quantum InfiniBand, ConnectX/BlueField NICs and DPUs, UFM, SHARP or equivalent)
- Container networking (CNI, BGP integration)
- Collective-communication libraries
- Multi-tenant VRF-based isolation
- Enterprise firewalls (FortiGate, Palo Alto)
- Storage networking (NVMe-oF)
- Bare-metal provisioning (MAAS, PXE, Redfish)
- Optical layer experience at 200/400/800G
- Greenfield data centre network build experience
- Professional certifications such as CCNP, CCIE or equivalent