Key Skills

Job Description

What we do 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 Network Engineer — BGP / Juniper / EVPN-VXLAN / GPU Cluster Networking The opportunity We run our own hosting infrastructure and production network, and we’re looking for a hands-on Network Engineer who enjoys real ownership: operating core connectivity, improving reliability, and building out capabilities that directly matter to customers. You’ll work on an environment with real routing (own ASN), real datacenter networking, and meaningful change-impact. If you like being close to the technology and seeing your work show up in production immediately, you’ll fit well. What you'll do Operate and improve our production network Maintain and evolve our Juniper routing and switching environment. Manage BGP operations on our ASN: routing policy, filtering, communities, troubleshooting, and traffic engineering. Operate EVPN/VXLAN in production and help extend it as we grow. Manage IPv4/IPv6 addressing and clean subnet allocation/assignment workflows. Design and expand network capabilities Independently translate customer requirements into practical network designs for our multi-tenant hosting environment, including addressing, VLAN/VXLAN segmentation, routing, firewalling, redundancy, and implementation planning, with senior design review available for more complex solutions. Help design and implement our expansion into internet exchanges and peering, including planning, implementation, validation, and ongoing operations. Implement routing-security best practices (e.g., RPKI/IRR hygiene and route-leak protections). Network security Perform security assessments of our existing network infrastructure, identifying vulnerabilities, architectural weaknesses, and opportunities for improvement. Design and implement practical security improvements, including network segmentation, firewall policies, access controls, and protection of management infrastructure. Maintain and improve our firewall environment, including policy management, rule hygiene, and secure customer isolation. Help develop and implement network security measures, including DDoS mitigation, in collaboration with our external senior network consultant when needed. Documentation, monitoring, and operational quality Use NetBox as the source of truth for network inventory and IP addressing. Improve monitoring, alerting, and network visibility, including telemetry, logging, and traffic analysis, using the existing toolchain and extending it where needed. Create and maintain diagrams, runbooks, and change documentation to improve operational reliability. Be helpful beyond networking when needed When network workload is lighter, support adjacent infrastructure areas (Linux, virtualization, storage, automation, or occasional customer escalations) depending on your strengths and team priorities. What we're looking for Core requirements Proven hands-on experience operating production networks, preferably in a multi-tenant hosting, datacenter, ISP, cloud, or service-provider environment. Strong practical knowledge of: BGP (policy, filtering, communities, troubleshooting). Datacenter switching and L2/L3 fundamentals. IPv4/IPv6 operations and addressing design. Practical knowledge of EVPN/VXLAN, preferably with hands-on production experience. Hands-on experience with network security, including firewall configuration and policy management, network segmentation, and secure network design. Ability to identify security weaknesses and implement appropriate improvements. Ability to independently translate technical requirements into practical network designs and implementation plans. Comfortable taking responsibility for production changes, including planning, validation, rollback procedures, and post-change checks. Fluent English (spoken and written). Big plus Hands-on experience with Palo Alto firewalls. Experience with internet exchange connectivity, peering, and routing security. Experience building DDoS mitigation workflows end-to-end. Experience driving improvements in environments with low structure (you bring structure without bureaucracy). Additional opportunities As Circle B expands its AI infrastructure, there may also be opportunities to contribute to GPU cluster networking. Experience with technologies such as RDMA/RoCE would be beneficial in this context, but is not expected for this position. The working style that succeeds here You take ownership while recognizing when to involve others for guidance or design reviews. You stay effective when priorities shift and interruptions happen. You communicate clearly during incidents and changes. You enjoy making systems more reliable, more visible, more secure, and better documented over time. Working model This is an on-site role in Hoofddorp, 5 days per week, to stay close to the hardware, platform engineering, and execution environment. Benefits Competitive salary. Pension scheme. Visa sponsorship. 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. If this sounds like a good fit, please send your CV and motivation letter to: [email protected]

Core Responsibilities

Operate and improve the production network, including Juniper infrastructure, BGP, EVPN/VXLAN, IP addressing, peering, and customer network designs. Strengthen network security and operational reliability through firewall management, monitoring, documentation, and carefully planned production changes.

Requirements

Candidates need hands-on experience operating production networks and practical expertise in BGP, datacenter switching, IPv4/IPv6, EVPN/VXLAN, and network security. They must be able to design and implement network solutions independently, manage production changes responsibly, and communicate fluently in English.

Benefits

• Pension Scheme
• Visa Sponsorship
• Company Gym
• Modern Office
• Conference and Exhibition Participation
• Professional Development Opportunities