Senior Network Engineer — AI / GPU Fabric

Circle B; Hoofddorp; On-site; EUR 120,000 - 180,000; Full time

Benefits offered by this job

Office in Hoofddorp

Informal and open culture

Conference opportunities

Job summary

Circle B is building a sovereign EU GPU cloud from the ground up. You will own the end-to-end network fabric, delivering a lossless backbone across multi-zone segments, with proper isolation, routing, and security.

Expect to work with RoCEv2/InfiniBand, BGP/EVPN in spine-leaf architectures, and modern switches. You will automate configuration and validation with Python, Ansible, and gNMI, while driving telemetry and drift detection as code.

Qualifications

• 7+ years in network engineering with production datacenter fabric experience.
• Deep experience with lossless fabrics (RoCEv2 or InfiniBand) in production.
• Strong BGP/EVPN/VXLAN in Clos/spine-leaf designs with ECMP and QoS.
• Hands-on with modern switch OS (SONiC/Cumulus/EOS) and network automation.

Responsibilities

• Own end-to-end network fabric design, deployment, and operation.
• Implement segmentation, firewalling, and multi-tenant isolation across zones.
• Lead automation and validation as code using Python/Ansible/gNMI.
• Collaborate across teams to ensure reliability, latency, and observability.

Skills

Network engineering

BGP/EVPN expertise

Automation with Python

Ansible

gNMI or vendor APIs

Self-directed workstyle

Tools

SONiC / Cumulus Linux / Arista EOS

Python

Ansible

gNMI

Job description

Circle B builds sustainable IT infrastructure for the AI and cloud era. For over a decade— we have designed and deployed datacenter, edge, and AI/HPC systems on Open Compute Project (OCP) hardware. We are independent, vendor-neutral, and ISO 9001 / 14001 / 27001 certified, with deployments across multiple countries.

Our newest initiative is a sovereign EU GPU cloud — operating under full Dutch/EU jurisdiction and beyond the reach of the US CLOUD Act, for regulated European organizations that cannot compromise on where their data lives.

The Role

You own the network end to end: the fabric that carries GPU traffic, the segmentation that keeps tenants and zones properly isolated, and the routing, firewalling, and load balancing that connect customers to compute.

What you will own

• The lossless GPU fabric across 800G-class switches, tuned for predictable RDMA performance. On Ethernet that means PFC, ECN, and DCQCN; on InfiniBand, the subnet manager and congestion control.
• Collective-communication (NCCL) performance across the fabric, working with the Infrastructure Engineer who owns the host side.
• Multi-zone segmentation: the revenue zone, the air-gapped sovereign zone, the management and internet zone, and the out-of-band network.
• The L2/L3 design: BGP, EVPN/VXLAN or the equivalent, VLANs, routing, and the controlled paths between zones.
• Firewalling and zero-trust at L3/L4: micro-segmentation, ACLs, and ingress/egress policy.
• Load balancing and ingress for platform and tenant traffic.
• The out-of-b and BMC management network.
• Datacenter interconnect and any carrier or cross-connect work at AMS3.
• Fabric automation: switch configuration, validation, and drift detection as code.
• The telemetry the Platform Engineer needs: error counters, congestion metrics, and link health.

What We Are Looking For

Required

• 7+ years in network engineering, including 4+ years building and running production datacenter fabrics.
• Deep production experience with a high-performance lossless fabric: either RoCEv2 Ethernet (PFC, ECN, DCQCN) or InfiniBand (UFM, subnet manager, SHARP). Real experience, not just lab familiarity.
• Strong BGP and EVPN/VXLAN in a Clos / spine-leaf design: ECMP, fast convergence, QoS, and jumbo frames.
• Production experience on a modern switch OS such as SONiC, NVIDIA Cumulus Linux, or Arista EOS.
• Network automation with Python, Ansible, and gNMI or vendor APIs: configuration and validation as code.
• Segmentation and firewalling for multi-tenant or regulated environments.
• Self-directed: you diagnose, propose, carry it out, and document.

Nice to have

• Hands-on with NVIDIA Spectrum-X (Ethernet) or Quantum InfiniBand on the current 800G switch and ConnectX-8 / BlueField generation.
• 400/800G optics and high-radix switches at scale: link bring-up and fault isolation under load.
• Rail-optimised or fat-tree topologies and GPU collective traffic (NCCL, GPUDirect RDMA).
• Familiarity with the NVIDIA Cloud Partner (NCP) reference architecture and its network model.
• Streaming telemetry (Prometheus, Grafana, gNMI).
• Regulated, sovereign, or air-gapped network design, and awareness of GDPR, DORA, NIS2, and NEN 7510.
• Experience at a GPU cloud, AI provider, HPC centre, or a low-latency trading environment.

Why Join Us

• Help build a sovereign EU GPU cloud from the ground up.
• Own a critical platform layer, not just tickets or maintenance.
• Work on modern AI infrastructure, GPU platforms, Kubernetes, observability, and automation.
• Join a company with deep experience in OCP, datacenter, AI/HPC, and cloud infrastructure.
• Build infrastructure for organizations where data location, compliance, and reliability truly matter.
• Company gym.
• Modern office in Hoofddorp.
• Informal and open working culture.
• Participation in relevant conferences and exhibitions across Europe.
• Opportunity to develop your skills in a fast-growing technology environment.

Our Work Culture

Circle B offers an informal working atmosphere with energetic people who enjoy being part of a growing technology company. We have an open management culture and encourage colleagues to contribute to improving our products, services, and processes.