Location
London

Hours
Full Time

Salary
Competitive, commensurate with experience

About the Role
Fuse Energy is a forward-thinking renewable energy startup on a mission to deliver a terawatt of renewable energy - fast. We're combining first-principles thinking with cutting-edge technology to build a radically better energy system. Having raised $210M from top-tier investors, we are scaling rapidly and seeking an HPC Network Engineer to design, deploy, and operate the network fabric for our multi-tenant AI cluster.

You will be responsible for the full stack of networking: 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 that ensures recoverability. Beyond the data centre, you will own the office network and act as the networking authority for the company, raising the bar by sharing your expertise.

Your ownership will span from architecture through day-2 operations, including designing and operating lossless RDMA-capable fabrics, building and managing leaf-spine data centre fabrics with routed underlay and overlay designs, implementing per-tenant network isolation, automating network provisioning and validation, and building telemetry and observability systems to proactively detect congestion and link degradation.

Additional responsibilities include troubleshooting performance issues end-to-end, operating out-of-band management networks, supporting tenant onboarding with segmentation and capacity planning, writing clear design documentation, maintaining the office wired and wireless infrastructure, and upskilling colleagues through documentation and collaborative sessions.

Experience
- 5+ years as a network engineer operating production data centre networks
- Strong dynamic routing experience (BGP in particular), plus overlay/encapsulation design and troubleshooting (e.g. EVPN/VXLAN)
- Hands-on experience with leaf-spine / Clos fabric design and operation
- Experience with modern data centre network operating systems and comfortable in the Linux networking stack
- Practical RDMA fabric experience: lossless Ethernet (e.g. RoCEv2 with PFC/ECN/DCQCN tuning) or InfiniBand
- Network automation as a working practice: scripting (e.g. Python), configuration management (e.g. Ansible), config generation from a source of truth, version-controlled changes
- Solid Linux administration fundamentals
- Experience with network telemetry and monitoring (e.g. Prometheus/Grafana, sFlow/IPFIX, streaming telemetry)
- Experience running corporate/campus networks: wired and wireless, switching, NAC/802.1X, VPN and remote access (e.g. Cisco Catalyst/Meraki or comparable)
- Clear communicator who enjoys teaching and knowledge sharing

About you
Detail-oriented and proactive network engineer passionate about high-performance and scalable network design. You thrive in a fast-paced startup environment and enjoy mentoring colleagues to elevate team capabilities. You have a strong sense of ownership and a drive to build robust, observable, and automated network infrastructures that support cutting-edge AI workloads.

Qualifications
- Relevant certifications (e.g. CCNP/CCIE or equivalent) are valued as evidence of depth but not mandatory
- Nice to have:
- Experience with GPU cluster networking (e.g. NVIDIA Spectrum-X, Quantum InfiniBand, ConnectX/BlueField NICs and DPUs)
- Container networking experience: CNI plugins and BGP integration
- Understanding of collective-communication libraries and fabric impact on training/inference performance
- Multi-tenant network design: VRF-based isolation, tenant bandwidth guarantees, secure shared infrastructure
- Experience with enterprise firewall platforms (e.g. FortiGate, Palo Alto)
- Storage networking experience (e.g. NVMe-oF, lossless storage fabrics)
- Bare-metal provisioning environments (e.g. MAAS, PXE, Redfish)
- Optical layer knowledge at 200/400/800G
- Experience standing up a data centre network from greenfield