Our final Interop·Labs event of 2025 was held last month at CableLabs headquarters in Louisville, Colorado. As with prior events, the week focused on interoperability aspects of the ONU Management and Control Interface (OMCI), defined via a combination of ITU-T Recommendation G.988 and the CableLabs Cable OpenOMCI specification.
This event continued our approach of pairing optical line terminals (OLTs) and optical network units (ONUs) from different suppliers to exercise real-world configurations, management and monitoring behaviors. Supplier engineering teams arrived with updated software, new device variants and a fresh set of test cases built from lessons learned through the year’s earlier interop events.
Supplier Participation in the XGS-PON Interop
Participating suppliers of customer premises equipment (CPE) brought a wide range of XGS-PON ONUs and PON residential gateways, representing multiple chipset families. These devices were paired with OLT platforms from Calix (E7-2) and Nokia (Lightspan MF-2) in a collaborative lab environment designed to exercise aspects of the OMCI implementation of the ONUs.
The diversity of CPE devices — including those based on PON SoCs not previously tested at these events — created meaningful multi-vendor pairings. Several new ONU suppliers also joined this event, expanding the ecosystem represented in our lab.
For the November interop event, the following suppliers provided CPE devices: Calix (ONU and multiple gateways), Gemtek (gateway), Hitron (multiple ONUs), Nokia (multiple ONUs and gateway), Sagemcom (ONU and gateway), Sercomm (ONU), Ubee (ONU and gateway) and Vantiva (ONU).
Testing Environment and Themes
As with our August event, each OLT supplier had a dedicated workbench with a small-scale PON Optical Distribution Network. Engineers used OLT debugging tools and our XGS-PON analyzer to collect OMCI traces and performance data.
During the week of testing, engineers focused on several interoperability-related themes:
- The impact of the extended VLAN tagging — Downstream mode attribute on the handling of Priority Code Point (PCP)-marked frames
- OLT configuration to support vendor-specific gateway eRouter VLAN IDs
- MAC Bridge Service Profile (CPE MAC learning) behavior
- 64-bit Ethernet frame counter performance monitoring reporting
- Forwarding of jumbo Ethernet frames
- Notification and alarm behavior of ONU Ethernet link state changes
- Software download and activation processes
Across these themes, the goal of the event remained clear: identify inconsistencies, understand root causes and convert findings into actionable improvements. Test results were encouraging. Many items identified in earlier events have been addressed by suppliers, even as this expanded test coverage uncovered additional issues that will guide our next round of improvements.
This event capped a productive year of XGS-PON interoperability testing at CableLabs. Throughout 2025, we steadily grew supplier participation, evolved the test plan to cover critical OMCI features more thoroughly and expanded support for diverse device types — specifically integrated PON gateways.
In February, CableLabs brought together three OLT suppliers to test their DOCSIS Adaptation Layer implementations, demonstrating how operators can use familiar DOCSIS-style configuration files to provision services on XGS-PON networks. The event validated the viability of this provisioning approach for operators transitioning to ITU-T PON technologies without replacing existing back-office systems.
During our April event, we focused more deeply on the Cable OpenOMCI, marking a milestone in the industry’s effort to improve cross-vendor compatibility. OLT suppliers from Calix, Ciena and Nokia paired their systems with ONUs from six suppliers to test five core OMCI functions.
Then, in August, CableLabs hosted another OMCI-focused event, bringing together the largest group of OLT suppliers yet, alongside seven ONU suppliers. Engineers tested requirements from the newly published I02 version of the Cable OpenOMCI specification, with expanded test cases covering ONU time synchronization and optical power levels.
Continuous Improvement Cycle
We plan to publish the I03 version of the Cable OpenOMCI specification — incorporating learnings from the April and August interop events — later this month. The findings from this event will be discussed in the CableLabs Common Provisioning and Management of PON (CPMP) working group and may generate new engineering change requests to the Cable OpenOMCI specification in the new year.
This cycle of lab testing, specification refinement and standards engagement is central to ensuring that XGS-PON networks can operate as truly multi-vendor systems.
See You Next Year
CableLabs has four additional PON Interop·Labs events scheduled in 2026, each focused on strengthening various aspects of ITU-T PON interoperability. We invite suppliers to join us in the CPMP and Optical Operations & Management working groups as we continue evolving our specifications. And we look forward to welcoming OLT and ONU suppliers back to our Louisville labs at our next interoperability event planned for January 2026.