HPC Network Engineer

DescriptionFuse 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.We've raised over $200M from top-tier investors including Balderton, Lakestar, Accel, Creandum, Lowercarbon, Ribbit, 20VC, Hummingbird and Collaborative Fund, alongside strategic angels including Nico Rosberg and GPs behind Meta, Revolut, Spotify and Uber.We're building a fully integrated energy company: developing our own solar, batteries and other generation projects, building our own hardware, improving and developing grid infrastructure, trading power in real time, using AI across the business, and installing distributed energy in homes. By selling directly to consumers we cut out the middleman, lower costs and pass the savings on to our customers.You'll design, deploy and operate the network fabric for our multi-tenant AI cluster: the high-performance compute and storage fabrics carrying RDMA traffic between GPUs, the tenant-facing and management networks, firewalling and tenant isolation, and the out-of-band infrastructure that keeps it all recoverable. Beyond the data centre, you'll own the office network and act as the networking authority for the company. You own the fabric from architecture through day-2 operations.ResponsibilitiesDesign and operate lossless, RDMA-capable fabrics (e.g. RoCEv2, InfiniBand) for GPU compute and storage traffic, including QoS, congestion control and buffer tuning at scaleBuild and manage leaf-spine data centre fabrics, with routed underlay and overlay design (e.g. BGP, EVPN/VXLAN)Implement and maintain per-tenant network isolation across compute, storage and management planesAutomate network provisioning, configuration and validation, treating switch config as code (e.g. Ansible, Python, NetBox as source of truth), deployed through CIBuild telemetry and observability for the fabric: flow-level and buffer-level visibility, dashboards and alerting that catch congestion and link degradation before tenants doTroubleshoot performance issues end to end, from optics and cabling through switch buffers to NIC/DPU configuration and collective-communication behaviour on the hostsOperate the out-of-band management network, console access and remote recovery pathsSupport tenant onboarding: segmentation and addressing, bandwidth and isolation guarantees, and capacity planning as the cluster scalesWrite clear design documentation capturing decisions, rationale and rejected alternativesOwn and maintain the office network: wired and wireless infrastructure, firewalling, VPN/remote access and office-to-data-centre connectivityUpskill colleagues on networking through documentation, run-throughs and pairingRequirements5+ years as a network engineer operating production data centre networksStrong 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 operationExperience with modern data centre network operating systems and comfortable in the Linux networking stack, not just a vendor CLIPractical RDMA fabric experience: lossless Ethernet (e.g. RoCEv2 with PFC/ECN/DCQCN tuning) or InfiniBand, understanding why lossless behaviour matters for GPU workloadsNetwork automation as a working practice: scripting (e.g. Python), configuration management (e.g. Ansible), config generation from a source of truth, version-controlled changesSolid Linux administration fundamentals: you can debug from the host side as well as the switch sideExperience 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 accessClear communicator who enjoys teachingBonus: GPU cluster networking (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 at 200/400/800G; greenfield data centre network build; CCNP/CCIE or equivalentBenefitsCompetitive salary and eligibility for equityBiannual bonus schemeFully expensed tech to match your needsPrivate health insuranceBreakfast and dinner allowance for office-based employeesAs we hire globally, benefits vary by location.Job SummaryID: 6F6AFE8C31Department:Type: full time