Network Engineer

Sesterce Group; San Francisco (CA); On-site; USD 120,000 - 160,000; Full time

Job summary

Sesterce Group is seeking a skilled networking engineer to design, deploy, and operate the network infrastructure for their GPU AI factories. The role includes working with InfiniBand and high-speed Ethernet fabrics and managing automation pipelines.

The ideal candidate will have a minimum of 4 years of datacenter networking experience, including familiarity with RDMA and strong Linux networking skills. Responsibilities also include troubleshooting network performance during live AI training runs.

Qualifications

• Minimum of 4 years of datacenter networking experience.
• Familiarity with RDMA, RoCE v2, and GPU training cluster communication.
• Experience using network-as-code tooling.

Responsibilities

• Design and deploy InfiniBand and high-speed Ethernet fabrics.
• Configure and operate network equipment and manage overlays.
• Tune transport for collective communication workloads.
• Maintain network automation pipelines across all sites.
• Troubleshoot performance regressions during live AI training.

Skills

Datacenter networking experience

InfiniBand or 400G/800G Ethernet knowledge

Linux networking internals

Network automation tools

Low-level diagnostics interpretation

Tools

Ansible

Terraform

Netbox

Job description

You will design, deploy, and operate the network infrastructure underpinning Sesterce's GPU AI factories across Europe — owning the full stack from physical cabling to BGP policies and RDMA fabric tuning.

What you will do

• Design and deploy InfiniBand (NDR 400G / HDR) and high-speed Ethernet fabrics for GPU clusters of 1,000+ nodes
• Configure and operate Arista, Juniper, and Mellanox/NVIDIA equipment; manage BGP, OSPF, and VXLAN overlays
• Tune RoCE and InfiniBand transport for collective communication workloads (NCCL, UCX)
• Maintain network automation pipelines (Ansible, Netbox, Nautobot) across all sites
• Troubleshoot performance regressions, packet loss, and congestion during live AI training runs

What we are looking for

• 4+ years of datacenter networking experience, including InfiniBand or 400G/800G Ethernet at scale
• Deep familiarity with RDMA, RoCE v2, and GPU training cluster communication patterns
• Solid command of Linux networking internals (DSCP, ECN, PFC, adaptive routing)
• Experience with network-as-code tooling (Ansible, Terraform, Netbox) and CI/CD pipelines
• Ability to interpret low-level diagnostics (tcpdump, perftest, ib_write_bw) and correlate with application performance