The final Interop·Labs event of 2025 was held last month at CableLabs’ headquarters in Louisville, Colorado. As with previous events, the week focused on the interoperability aspects of the ONU’s management and control interface (OMCI), which are defined by a combination of Recommendation ITU-T 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 practice realistic configurations, management and monitoring behaviors. Vendor engineering teams arrived with updated software, new hardware variants, and a new set of test cases built on lessons learned through previous interoperability events of the year.
Supplier participation in XGS-PON Interop
Participating customer premises equipment (CPE) suppliers brought a wide range of XGS-PON ONUs and residential PON gateways, representing multiple chip families. These devices were coupled with OLT platforms from Calix (E7-2) and Nokia (Lightspan MF-2) in a collaborative laboratory environment designed to practice aspects of OMCI implementation for ONUs.
The diversity of CPE devices – including devices based on PON SoCs that had not been previously tested at these events – created meaningful multi-vendor pairings. Many new ONU suppliers also joined the event, expanding the ecosystem represented in our lab.
For the November interoperability event, the following vendors provided CPE devices: Calix (ONU and multi-gateway), Gemtek (gateway), Hitron (multi-ONU and gateway), Nokia (multi-ONU and gateway), Sagemcom (ONU and gateway), Sercomm (ONU), Ubee (ONU and gateway), and Vantiva (ONU).
Test environment and subjects
As with the August event, each OLT supplier had a dedicated workbench with a small-format PON optical distribution network. Engineers used OLT debugging tools and our XGS-PON analyzer to collect OMCI traces and performance data.
During the testing week, engineers focused on several topics related to interoperability:
Impact of Extended VLAN tags – downstream mode attribute on handling of frames tagged with Priority Code Point (PCP) OLT configuration for vendor-specific gateway support eRouter VLAN IDs Bridge MAC service IDs (CPE MAC learning) 64-bit behavior of Ethernet frame counter performance monitoring reports Forwarding of jumbo Ethernet frames Notification and alarm behavior for Ethernet ONU link state changes Software downloads and activations
Across these themes, the goal of the event remained clear: identify discrepancies, understand root causes, and transform findings into actionable improvements. The test results were encouraging. Many of the items identified in previous events have been addressed by vendors, even as this expanded test coverage has revealed additional issues that will guide our next round of improvements.
This event capped off a productive year of XGS-PON interoperability testing at CableLabs. Throughout 2025, we have steadily increased supplier engagement, advanced our testing plan to more comprehensively cover important OMCI features and expanded support for diverse device types – specifically embedded PON gateways.
In February, CableLabs brought together three OLT vendors to test their DOCSIS Adaptation Layer implementations, demonstrating how operators can use familiar DOCSIS-style configuration files to provide services on XGS-PON networks. This event demonstrated the feasibility of this provisioning approach for operators moving to ITU-T PON technologies without replacing existing back-office systems.
During the April event, we focused more deeply on Cable OpenOMCI, marking a major milestone in the industry’s efforts to improve vendor interoperability. OLT suppliers from Calix, Ciena and Nokia interfaced their systems with ONUs from six vendors to test five core OMCI functions.
Then, in August, CableLabs hosted another OMCI-focused event, bringing together the largest group of OLT suppliers to date, along with seven ONU suppliers. Engineers tested requirements from the newly published I02 version of the OpenOMCI Cable specification, with expanded test cases covering ONU time synchronization and optical power levels.
Continuous improvement cycle
We plan to publish version I03 of the OpenOMCI Cable Specification — which includes lessons learned from the interoperability events in April and August — later this month. The results of this event will be discussed in the CableLabs Co-Provisioning and PON Management (CPMP) working group and may generate new engineering change requests for the Cable OpenOMCI specification in the new year.
This cycle of laboratory testing, specification improvement, and standards sharing is key 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 for 2026, each focused on enhancing different aspects of ITU-T PON interoperability. We invite suppliers to join us in the CPMP, Optical Operations and Management working groups as we continue to develop our specifications. We look forward to welcoming OLT and ONU suppliers back to our laboratories in Louisville at the next interoperability event planned for January 2026.”
