Network Engineer - InfiniBand / UFM

We are seeking an experienced Senior Network Engineer (InfiniBand / UFM) to design, deploy, automate, and operate next-generation AI Factory networking infrastructure supporting large-scale GPU clusters. This role is responsible for building and maintaining high-performance NVIDIA Quantum InfiniBand fabrics that power AI training and inference environments utilizing NVIDIA UFM, NCCL, RoCEv2, and modern data center technologies., The ideal candidate has deep expertise in InfiniBand networking, NVIDIA Unified Fabric Manager (UFM), large-scale GPU deployments, Linux networking, automation, and troubleshooting distributed AI workloads. What You'll Do

• Design, deploy, and maintain large-scale NVIDIA InfiniBand fabrics supporting AI/ML GPU clusters.
• Deploy and administer NVIDIA Unified Fabric Manager (UFM) Enterprise for monitoring, provisioning, telemetry, and fabric health.
• Configure and optimize NVIDIA Quantum and Quantum-2 InfiniBand switches.
• Troubleshoot fabric performance issues impacting NCCL, MPI, GPUDirect RDMA, and AI training jobs.
• Implement and validate fat-tree, Dragonfly+, Clos, and spine-leaf network architectures.
• Perform firmware lifecycle management for InfiniBand switches, adapters (HCAs), and UFM infrastructure.
• Optimize congestion control, adaptive routing, QoS, and traffic engineering for high-performance GPU communication.
• Work closely with AI platform, GPU infrastructure, storage, and systems engineering teams to deploy scalable AI Factory environments.
• Automate network provisioning using Python, Ansible, Git, REST APIs, and Infrastructure-as-Code methodologies.
• Monitor network health using UFM telemetry, Prometheus, Grafana, and other observability platforms.
• Support high availability, maintenance windows, incident response, root cause analysis, and capacity planning.
• Participate in architecture reviews and define networking standards for AI infrastructure.

• 7+ years of data center networking experience.
• 3+ years supporting NVIDIA InfiniBand environments.
• Hands-on experience with NVIDIA UFM Enterprise.
• Experience deploying and operating Quantum and Quantum-2 InfiniBand switches.
• Strong understanding of:

• InfiniBand Architecture
• Subnet Manager (SM)
• Adaptive Routing
• Congestion Control
• Partition Keys (PKeys)
• LIDs
• Queue Pairs (QP)
• Virtual Lanes (VL)
• Service Levels (SL)

• Strong Linux administration experience (Ubuntu).
• Experience with automation using Python and Ansible.
• Deep understanding of Layer 2 and Layer 3 networking.
• Experience with BGP, EVPN, VXLAN, and modern spine-leaf architectures.
• Experience with packet captures and troubleshooting using tcpdump, Wireshark, and ibdiagnet tools.
• Excellent troubleshooting and communication skills.

What You Bring

• 10+ years of experience in large-scale data center networking

• Deep expertise in spine-leaf architectures and L3 fabrics

• Strong experience with BGP, EVPN, VXLAN

• Experience operating high-performance computing (HPC) or GPU-dense environments

• Experience designing networks for hyperscalers, neoclouds, or high-scale SaaS infrastructure

• Strong automation background (Python, Ansible, Terraform, or similar)

• Experience with network observability tooling and telemetry pipelines Proven ability to design systems that scale to thousands of nodes

• Strong documentation and architectural communication skills

Nice to Have

• Experience with Netris and Terraform.
• Experience with multi-region backbone design
• Exposure to bare-metal provisioning systems
• Experience working in high-growth infrastructure startups

The network is the foundation of distributed AI training. Performance bottlenecks at the fabric layer directly impact customer workloads.

This role will shape how Voltage Park scales from tens of thousands of GPUs to significantly beyond - ensuring deterministic performance, predictable scaling, and enterprise-grade reliability.

If you want to architect infrastructure that powers frontier AI research, this is the role.

We are committed to offering competitive compensation that reflects the value each team member brings to our mission. Final offers are based on factors such as experience, skills, geographic location, and role expectations. In addition to base salary, our total rewards package for eligible roles includes a discretionary bonus, a meaningful equity component, and comprehensive benefits.

The anticipated annual base salary range for this role is:

$170,000-$210,000 USD

Benefits and Perks

We offer a comprehensive and competitive benefits package designed to support our employees' health, well-being, and long-term success:

• Comprehensive Health Coverage: Medical, dental, and vision coverage for employees and eligible dependents.
• Meaningful Equity: RSUs that give employees a stake in the company's long-term success.
• Retirement Savings: 401(k) matching (U.S.) and pension contributions (U.K.).
• Flexible Time Off: Unlimited PTO, company holidays, and floating holidays to support work-life balance.
• Company-Wide Winter Break: Two weeks of company closure each winter to disconnect and recharge.
• Paid Parental & Family Leave: Paid leave to support you and your family through life's important moments.
• Professional Development: Annual learning and development allowance to support your professional growth.
• Wellness Benefits: Wellness and work-from-home stipends to support your physical and mental well-being.
• Sabbatical Program: Four weeks of paid sabbatical leave after four years of service.
• Flexible Work: Flexible schedules and a hybrid work model for our office-based teams.
• In-Office Meals: Complimentary meals at our office hubs.

Lightning AI is the company behind PyTorch Lightning. Founded in 2019, we build an end-to-end platform for developing, training, and deploying AI systems-designed to take ideas from research to production with less friction. Through our merger with Voltage Park, a neocloud and AI Factory, Lightning AI combines developer-first software with cost-efficient, large-scale compute. Teams get the tools they need for experimentation, training, and production inference, with security, observability, and control built in. We serve solo researchers, startups, and large enterprises. Lightning AI operates globally with offices in New York City, San Francisco, Seattle, and London, and is backed by Coatue, Index Ventures, Bain Capital Ventures, and Firstminute. Who We look for The people who thrive here are builders who move fast, communicate openly, take ownership, and continuously improve themselves, their teams, and our company. Here's what that looks like in practice: * Move with Urgency: We move quickly, make thoughtful decisions, and keep momentum. We value action over perfection and learn by shipping. * Take Ownership: We own outcomes, not just our individual work. We make decisions that move the company forward and follow through. * Communicate Openly: We communicate directly, seek to understand, and create clarity for others. Honest conversations help us move faster together. * Build Great Teams: We lead by example, empower others, and create healthy teams where people can do their best work. * Raise the Bar: We're always improving ourselves. We learn from feedback, consistently challenge ourselves to grow, and focus on the work that matters most. * Think Long-Term: We design for what's next. We create scalable systems, simplify complexity, and use AI and automation to amplify our impact.