From Plugfest to Progress: Key Lessons from the 2025 HSN Plugfest
By: Sam Johnson, Engineering Manager at Intel Corp and Ethernet Alliance HSN Subcommittee Chair
“Interoperability” is my favorite buzzword in the world of Ethernet, because it is a word that goes straight to the heart of what makes Ethernet such a powerful technology. Interoperability is the promise of Ethernet, and that promise has been built and maintained throughout 50 years of technological advancements. However, Ethernet technologies are reaching an interesting inflection point, where hyperscaler demand for faster and faster speeds is pushing boundaries beyond anything we’ve seen before. As speeds increase at an unprecedented rate and implementations get ever more complex, maintaining interoperability becomes more critical and challenging than ever. At higher data rates, especially those operating beyond the latest specifications, assumptions break down quickly and our ability to maintain the promise of Ethernet depends on engineers being able to come together to test, measure, and learn. And that’s where the Ethernet Alliance High Speed Networking (HSN) Plugfest comes in.
In December 2025, the Ethernet Alliance hosted its latest HSN Plugfest. System vendors, interconnect providers, and test and measurement companies met to evaluate interoperability and conformance across a wide range of configurations. This was the first Plugfest centered on emerging 224G technologies, and it offered a snapshot of where the ecosystem is today as well as where more focus is needed.
A Broad but Realistic Test Environment
One of the HSN Plugfest’s greatest strengths is the varied testing grounds that it provides. Multiple form factors, a wide array of interconnects, and multitudes of configuration combinations, spanning both established and early-stage technologies, were all present at the December event. Participants were able to test against a wide array of interoperability partners, including devices that would be difficult (if not impossible) to assemble in a single lab, for example, pre-release products and early silicon implementations.
This breadth matters. The hardest interoperability challenges present themselves when devices are exercised outside of familiar or tightly controlled environments. Plugfests create the opportunity to see how systems behave when faced with real-world diversity, not just ideal conditions. They also allow the engineers to work directly together, building relationships across the industry, and removing the hurdles that are in place if these problems are being tackled after products are deployed in the field.
Interoperability in Motion: Solid Progress, But Real Work Ahead
The overall 224G-based link establishment results from the event were encouraging for a technology that’s so early in its lifecycle, with an approximately 90% link establishment success rate seen across all interoperability test combinations. These measurements were taken across a variety of host devices (switches, PHYs, and test equipment) and an even broader range of interconnect types, including copper cables, retimed optics, linear optics, linear receive optics, active optical cables, and active copper cables (with and without retimers). Future events will likely focus in on more specific configurations, but it was helpful to maximize the breadth of this first 224G event to get an idea of the landscape in front of us. A 90% success rate sounds high, but it’s in the 10% of failures that the real challenges lie, as well as in the areas still untested, such as the new and minimally implemented ILT (Inter-sublayer Link Training).
The event also provided an important reminder that the work doesn’t end just because a specification is completed and a technology deployed. While emerging 224G was the primary focus of the event, past events showed us that more work was needed in the 112G space, and this latest event only further confirmed that. Many of the current 112G deployments are constrained to and tested within a limited configuration space, but the plugfest removes those constraints and shines a spotlight on the true status of the technology. This is critical to do since the new speeds and technologies will be proliferated more broadly over time, and each new use case is a potential interoperability challenge if the technology implementation is not healthy.
The results from the latest event were clear; 112G work isn’t finished yet! Perhaps because of the focus on 224G, or because of the added complexity of Auto-Negotiation and Link Training which 224G has not broadly implemented yet, 112G results were actually worse than 224G results. The advantage of finding these issues in the Plugfest space was clear to all involved: there was no angry customer demanding daily updates, deep dive testing was enabled and protected under the event NDA, and the engineers worked directly together to resolve issues. Every problem solved in this manner provides a huge gain to the participants by preventing those issues from occurring in the field.
Conformance vs. Interoperability: Where Reality Shows Up
One of the main goals of the plugfest was to gather conformance data and see how well it aligned with real interoperability results. Some of this testing centered on IEEE 802.3dj TP2 measurements for optical modules, as space where the IEEE was interested in gathering a broader dataset from across the industry. The conformance measurements were anonymized and reported to the IEEE for consideration during the finalization of the 224G spec, but a clear correlation between interop issues and conformance results was not generally present.
That doesn’t take anything away from the value of conformance testing, though. Instead, it reinforces why plugfests matter. Compliance with the standards is the foundation of Ethernet’s promise of interoperability, and lack of compliance may be the cause of some issues, but interop failures are often caused by configuration misalignment, host/interconnect incompatibility, and protocol issues not uncovered by conformance testing. Seeing how systems act in real, multi-vendor environments helps highlight where specifications need to be clearer, where extra measurements might be useful, and where common assumptions could use another look. Those insights feed directly back into IEEE standards work, grounding theoretical discussions in concrete reality.
In the Room Where Interoperability Happens
The plugfest demonstrated that the value of simply being in the room where the interoperability work happens often outweighs even the test results generated. Participants had the chance to go hands-on with cutting edge (and VERY expensive) conformance and interoperability test setups – optical and electrical test points, high-bandwidth VNAs, stressed BERT environments, and fully functional interconnect stations. They were working side-by-side with industry peers with deep expertise across silicon, optics, systems, and measurement, at times testing on systems that won’t be available in the market for months or longer.
And the real benefit goes beyond just equipment access. Plugfests are a safe, private environment where engineers can share information, investigate problems, and collaborate on solutions, without worrying about public disclosure or competitive pressures. These candid real-time conversations, with the right people at the right time, are hard to recreate elsewhere. That combination of trust, technical depth, and direct teamwork is what makes participation matter.
Turning Progress Into Practice
As Ethernet muscles its way toward higher speeds, interoperability challenges take center stage in the fight for reliability, and the December 2025 HSN Plugfest reflected that reality. Plugfests come into their own by providing a practical path from early builds to robust, deployment-ready systems.
Looking ahead, the HSN Subcommittee will continue plotting future events based on member input and evolving industry needs. As Ethernet continues to scale, these shared testing efforts remain an important part of making sure higher speeds translate into solutions that are not just fast, but ready for the real world. If you see the value of this work, then please join us in the HSN and help us lead the way towards keeping Ethernet as the leading-edge, openly interoperable and versatile technology that it is!
