Deep Tech Networking Engineer, DPDK / Linux - Paris - H/F

Iliad - Free; Paris; Hybrid; EUR 85,000 - 120,000; Full time

Benefits offered by this job

Remote working days

On-site restaurants

Transport reimbursement 70%

Swile meal card

Health and income protection coverage

Time Savings Account (CET)

Employee benefits through the CSE

Job summary

Iliad - Free in Paris is seeking a Deep Tech Networking Engineer to design, develop and optimize high-performance networking systems from hardware to the dataplane. You will work with DPDK, Linux, embedded targets and collaborate with vendors to deliver upstreamable solutions.

We value hands-on contributors who can ship impactful patches and demonstrate measurable performance improvements. A hybrid schedule with on-site facilities and remote days is available in Paris.

Qualifications

• Strong C programming skills and knowledge of Linux systems.
• Experience with high-performance packet processing.
• Familiarity with Linux kernel networking and embedded systems.
• Ability to measure and optimize performance with metrics.

Responsibilities

• Design, develop and optimize high-performance networking systems from hardware to dataplane.
• Build packet-processing pipelines with DPDK and related PMDs.
• Connect Linux control plane to dataplane via netlink.
• Maintain kernel exception paths using virtio-user, TAP and shared memory rings.
• Develop Linux networking on embedded targets (drivers, XDP, AF_XDP).
• Collaborate with SoC and NIC vendors on upstreamable solutions.
• Submit, review patches and engage with maintainers.
• Write design docs and guide other engineers.
• Bring up stack on target hardware and measure performance baselines.
• Investigate production issues like drops and cache contention.

Skills

C programming

Linux systems

Networking (L2/L3)

DPDK

Performance optimization

Kernel networking

English documentation

Tools

DPDK

VPP

ODP

AF_XDP

OVS-DPDK

Job description

Deep Tech Networking Engineer, DPDK / Linux - Paris - H/F

• Temps complet

At Free/Iliad, we build embedded networking products including 5G and edge gateways, OLTs, carrier-grade routers and NPU-based appliances.

Our systems forward tens to hundreds of Gbps on Arm64 SoCs, x86, ASICs and DPUs, within strict power and hardware constraints. The dataplane runs on DPDK or dedicated hardware, while Linux remains the control plane.

Performance is not theoretical. We measure Mpps, p99 latency, jitter and watts per Gbps on real hardware deployed at scale.

Open source is also central to how we work. Rather than maintaining private patches through every rebase, we contribute improvements to DPDK, Linux, U-Boot and Buildroot. Depending on the project and your experience, upstream work may represent between 20% and 80% of your time. It is planned and tracked like any other deliverable.

We are looking for engineers who want to make packets go faster, understand why they go faster and prove it with numbers.

Your role :

You will design, develop and optimise high-performance networking systems from the hardware to the dataplane.

Your responsibilities will include:

• Building packet-processing pipelines with DPDK, including PMDs, mempools, mbufs, rings, lcores, eventdev, graph libraries and QoS.
• Connecting the Linux control plane to the dataplane by synchronising routes, neighbours and interfaces through netlink.
• Maintaining exception paths to the kernel using technologies such as virtio-user, TAP and shared-memory rings.
• Developing Linux networking on embedded targets, including netdev and PHY drivers, phylink, DSA, switchdev, TC flower, XDP and AF_XDP.
• Working close to the hardware with VFIO, IOMMU, hugepages, CPU isolation, device trees, U-Boot and Buildroot.
• Profiling and measuring performance with perf, ftrace, bpftrace, PMU counters, TRex, pktgen and testpmd.
• Investigating complex production issues such as intermittent packet drops, descriptor exhaustion, cache contention and IOMMU faults.
• Working directly with SoC and NIC vendors on drivers, firmware interfaces and upstreamable solutions.
• Submitting and reviewing patches, responding to maintainers and following changes until they are merged.
• Writing design documents, reviewing code and helping other engineers grow.

Your scope will depend on your experience. You may start by owning a feature, a PMD or a board family, or take responsibility for the architecture of an entire dataplane subsystem across several products.

During your first year, you will bring up our stack on target hardware, reproduce existing performance baselines and deliver a measurable improvement on a production platform.

Your profile :

We are open to both experienced open-source contributors and engineers with excellent foundations who want to develop deep expertise in Linux networking and packet processing.

You have:

• Strong C programming skills and a solid understanding of Linux systems.
• Good knowledge of L2 and L3 networking, including Ethernet, VLAN, IPv4/IPv6, ARP/ND, routing, FIB lookups, VXLAN, GRE and IPsec.
• Experience with DPDK or another high-performance packet-processing stack such as VPP, ODP, AF_XDP or OVS-DPDK.
• An understanding of performance topics such as caches, NUMA, DMA, PCIe and SR-IOV.
• Experience or strong interest in Linux kernel networking, embedded systems, drivers, cross-compilation or board bring-up.
• A disciplined approach to optimisation: measure, change, compare and document.
• Clear written English for technical documentation, code reviews and upstream discussions.

You do not need to have mastered every technology listed in this announcement. We will pay particular attention to what you have built, how deeply you understand it and how you demonstrate its technical impact.

Public open-source contributions are valuable. If your strongest work is closed-source, be ready to explain the technical decisions you made, the constraints you faced and the results you achieved.

For Staff and Senior Staff positions, we expect a proven public track record through patches, reviews, maintainer responsibilities or contributions to projects such as DPDK, Linux, U-Boot, Buildroot, Zephyr, Yocto, FRR or VPP.

Experience with SmartNICs or DPUs such as NVIDIA BlueField, Marvell OCTEON, NXP DPAA2 or Intel IPU is a plus, as is experience with switchdev, SAI, SONiC, PTP, TSN, KernelCI, LAVA or DPDK DTS.

What matters most is what you have shipped, what you can demonstrate and the technical impact you want to create.

Recruitment process

• 15-minute phone screen with Steve, the recruiter
• 30-minute interview with Vincent, the hiring manager
• 60-minute technical interview
• 60-minute HR interview with Sarah and Steve
• Profit-sharing and incentive scheme based on the Group’s performance
• Reimbursement of your Free home internet plan
• One to two remote-working days per week
• On-site restaurants and cafeteria
• Numerous internal mobility opportunities across the Iliad Group
• Regular training opportunities and access to Free University to develop your skills
• Unique workspaces located in an iconic building that is part of Paris’s architectural heritage
• Public transport costs reimbursed up to 70%
• Swile meal card worth €10 per working day, with 60% covered by the company
• Comprehensive health and income protection coverage
• Time Savings Account, known in France as Compte Épargne Temps or CET
• Employee benefits through the CSE, including gift vouchers, discounts and exclusive offers