{"id":3988039,"url":"https://alion.io/job/radiant-principal-software-engineer-networking","title":"Principal Software Engineer - Networking","company":{"id":8822,"name":"Radiant","domain":"radiant.com","url":"https://alion.io/company/radiant","size_band":null,"is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"B","score":83,"open_postings":3,"ghost_share":0,"stale_share":0.667,"repost_share":0,"time_to_fill_p50_days":49,"computed_at":"2026-11-09T06:03:00Z"}},"role":"Backend","role_family":"Backend","seniority":"lead","employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Gloucester, United Kingdom"],"countries":["GB"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"BGP","optional":false},{"name":"InfiniBand","optional":false},{"name":"Kubernetes","optional":false}],"status":"live","first_seen_at":"2026-11-09T19:54:01Z","employer_posted_date":"2026-11-09","last_verified_at":"2026-11-09T22:19:01Z","board_verified":true,"closed_at":null,"days_open":0,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":0},"description":"What You'll Do\nAs a Principal Software Engineer - Networking, you will help set the technical direction for Radiant's networking software, and lead the design and delivery of the systems that build, automate, and operate the fabric connecting our GPU clusters.\nYou'll work across high-performance cluster fabrics, network automation, Managed Networks, and multi-tenant isolation. You'll partner closely with product, infrastructure, SRE, storage, and security teams, and with customers whose workloads depend on the network.\nThis is a hands-on technical leadership role focused on making our networks fast, reliable, and fully software-driven, through architecture, code, and the standards other teams build on.\nKey Responsibilities\nSet the technical vision and architecture for Radiant's networking software, and lead its design and implementation.\n\nDesign and build the control plane that provisions, configures, and automates our cluster fabrics and Managed Networks.\n\nTranslate product and customer requirements into robust architectures, APIs, and technical designs, working closely with Product.\n\nOwn network performance, isolation, and reliability for AI training and inference workloads.\n\nLead integration of networking with compute, Kubernetes, storage, security, and observability.\n\nDrive operational excellence with SRE and Infra Ops, including automation, monitoring, and incident response.\n\nRaise the engineering bar across the organisation through mentoring, design and code review, and technical standards.\n\nYour Profile\nExtensive experience building and operating large-scale network software or software-driven networks.\n\nA track record of technical leadership at staff or principal level, including setting direction across multiple teams and delivering complex, high-stakes systems.\n\nStrong hands-on engineering skills in one or more systems languages such as Go or similar.\n\nDeep technical expertise across:\n\nFabrics: RDMA, InfiniBand, RoCE, Ethernet at scale, congestion control\n\nNetworking: routing, switching, BGP, EVPN/VXLAN, overlays and underlays\n\nAutomation: network-as-code, configuration management, APIs for network devices\n\nMulti-tenancy: isolation, segmentation, network security\n\nHands-on experience with technologies such as NVIDIA networking, SONiC, Cumulus, or similar.\n\nUnderstanding of how network design affects AI training and inference performance.\n\nExcellent written and verbal communication, including clear design documents and explaining complex trade-offs to technical and non-technical audiences.\n\nComfortable working directly with customers on highly technical problems.\n\nWhat You Bring\nNetworking domain expertise: Understand how the network shapes workload performance, from the fabric up to the application.\n\nEngineering excellence: Write and review code that sets the standard for correctness, performance, and maintainability.\n\nArchitectural judgement: Make sound long-term decisions on systems that are hard to change once built.\n\nTechnical leadership: Influence direction across teams without relying on authority, and grow the engineers around you.\n\nSystems thinking: Understand how your area interacts with compute, networking, storage, and the rest of the cloud platform.\n\nOwnership: Drive capabilities from design through production, operation, and continuous improvement.\n\nQualities we look for:\nSet the standard: Every single day, you spot opportunities to constructively shake things up\n\nInspire the change: There's no blueprint for the future. You'll embrace challenges and change\n\nYou're real and you're true to yourself: We cherish and celebrate diversity so you'll feel right at home whoever you are and whoever you're talking to, you treat everyone the same.\n\nWhy should you join us?\nWhat sets us apart is our blend of modern technology, competitive benefits, and an open, welcoming work culture that enables our people to thrive.\nHere are just some of the great things you can expect from us:\n25 days of annual leave\n\nA culture that emphasises results over hierarchy, process & ego: we place great emphasis on the quality, ingenuity and creativity of work.\n\nOpen communication, regular feedback: we value smooth collaboration, direct and actionable feedback, and believe that leading with empathy and a growth mindset makes us better together.\n\nLearning Time: we all have dedicated learning time to focus on new skills, projects or interests that lay outside of your day-to-day job.\n\nHealth & Wellbeing: we want everyone to feel healthy and happy, so we offer private medical insurance via Bupa.\n\nCycle to Work Scheme: we're committed to building a sustainable business, so we encourage cycling to work.\n\nGympass subscription to a variety of gyms and wellbeing apps\n\nParticipation in the company shares program\n\nEnhanced parental pay & leave\n\nOur process: Talent screen → Hiring Manager → Technical interview (two Principal Engineers) → Whiteboard Exercise → Final.\nCompany Overview:\nRadiant is redefining how AI infrastructure is built.\nWe design and operate AI-native cloud platforms engineered for sovereignty, performance, and scale. Our infrastructure powers GPU-native workloads, multi-tenant control planes, and high-performance AI systems designed for the most demanding environments.\nWe are not building a generic cloud. We are building purpose-built AI infrastructure - from powered land, to compute, to software.\nAs we scale, we're building this organisation from the ground up. We're looking for people who'd rather build the playbook than inherit one - who are comfortable doing the work themselves as well as directing others, and who can adapt as fast as our strategy does. 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