400G ZR+ BiDi does not exist, it can't hurt you. Or can it? (denog17)

As it's common practice, each new hacker event needs something weird and funky. For this years summer camp in the Netherlands called WHY2025, we build a 400G link over a single fibre. Since 400G BiDi does not exist (yet), we had to get creative and built something, which might be considered out of spec. Licensed to the public under http://creativecommons.org/licenses/by/4.0 about this event: https://pretalx.com/denog17/talk/KLXJS8/
Video:denog17-78260-eng-400G_ZR_BiDi_does_not_exist_it_cant_hurt_you_Or_can_it_hd.mp4

Day 1 Closing (denog17)

That's a wrap on Day1, time for the social! Licensed to the public under http://creativecommons.org/licenses/by/4.0 about this event: https://pretalx.com/denog17/talk/MVDVUL/
Video:denog17-81768-eng-Day_1_Closing_hd.mp4

Understanding and optimising transceiver efficiency using internal metrics for improved power savings (denog17)

In high-performance optical communication systems transceiver health and efficiency are critical to network reliability and energy consumption. This presentation explores the powerful capabilities of Versatile Diagnostics Monitoring (VDM) features found in modern optical transceivers (beyond the speed of 100G) with a particular focus on the Thermoelectric Cooler (TEC) current metrics. By analysing TEC current alongside temperature and cable length data we should be able to identify the optimal operating conditions that will minimise power consumption while maintaining performance. In order to prove this thesis we developed a couple of software prototypes to perform the...

Ultra Ethernet: Addressing AI/HPC Interconnect Challenges Beyond the InfiniBand Monopoly (denog17)

For years, InfiniBand has dominated high-performance interconnects. Yet for strategic and technical reasons, there has been a huge industry ask to develop a new next-generation protocol for use in AI and HPC environments. This session introduces Ultra Ethernet, an innovative standard designed to tackle the limitations seen in RDMA around scalability, latency and congestion management, crucial for democratizing future AI/HPC build outs. Join us for a comprehensive exploration of the technologies poised to redefine Storage or GPU interconnectivity and challenge the status quo. We also discuss the future of the UEC and how collaboration among...

Th3 Flock of Bird s (denog17)

As Bird is evolving over the years and we now have Bird version 3 available at our fingertips, maybe we should know the capabilities of it and what performance we can expect from it. Get some numbers in comparison with other routing stacks. Let's take a quick look on the shiny new feathers Bird prepared for us. Licensed to the public under http://creativecommons.org/licenses/by/4.0 about this event: https://pretalx.com/denog17/talk/XRVTP3/
Video:denog17-78857-eng-Th3_Flock_of_Bird_s_hd.mp4

Newcommer Session (denog17)

Welcome to your first DENOG conference. In this session, we will guide you through the community, the event and everything DENOG! Licensed to the public under http://creativecommons.org/licenses/by/4.0 about this event: https://pretalx.com/denog17/talk/KFLJDB/
Video:denog17-81766-eng-Newcommer_Session_hd.mp4

"What can possibly go wrong?" Stories of peculiarities of modern server hardware (denog17)

After discussing building a 1 Tbps/1 Gpps load generator on commodity x86-64 hardware, one of the most common follow-up topics was the reasoning behind some of the decisions. And here I've realised that it is not commonly understood that modern systems are more complex than classic multi-socket NUMA systems, and that if you don't consider some of their peculiarities, you won't achieve the expected performance. In this talk, I want to explore what happens when you break those assumptions and how you can identify them. All examples would be based on the assumption that...

Forwarding packets at scale - Building a Cloud Data Plane using eBPF/XDP (denog17)

At Hetzner we’ve historically used an Open vSwitch based data plane for connecting hundred thousands of cloud servers to the network. This has served us well for many years and mostly still does. We have however reached some limitations and wanted to improve scalability, resiliency and flexibility with a more specialized data plane that's tailored to our needs while being easy to operate and building a strong foundation for new features. When checking our options back in 2022, the team reached the conclusion that the best path to achieve this goal is to build and...

Inventing the wheel - Network Orchestration at scale (denog17)

At DE-CIX, we're redefining network orchestration from first principles. Confronted with the limitations of existing systems, we set out to design a modern orchestration stack—one capable of managing a truly global network, seamlessly interfacing with a variety of upstream and downstream systems, supporting fully managed network devices, and, above all, delivering uncompromising reliability. In this talk, we share our transformation journey—from our starting point to our vision for the future. We'll delve into the architectural choices, design principles, and decision-making frameworks that guided our approach. We’ll also explore how we rigorously test our systems and...

Dein erster Congress? Die Chaospat:innen sind für dich auf dem 39C3 da!

Auch in diesem Jahr sind die Chaospat:innen wieder beim Chaos Communication Congress in Hamburg am Start!

Interessierte Mentor:innen und Mentees können sich bis zum 25. November 2025 um 23:59 Uhr UTC+1 auf unserer Chaospat:innen-Plattform registrieren.

Wir freuen uns auf viele neue Menschen, die zum ersten Mal das bunte, faszinierende Chaos auf dem 39C3 erleben wollen, vielleicht ja auch mit dir!

Wenn du dir ein bisschen Unterstützung oder Anschluss in einer Gruppe für deinen ersten Congress brauchst, bist du bei uns genau richtig.

Du bist neugierig auf den Congress, aber unsicher, ob du dich dort wohlfühlen wirst? Du hast vielleicht spezielle...