In a recent CableLabs XGS-PON Interop·Labs event, suppliers of optical line terminals (OLTs) and optical network units (ONUs) expanded interoperability testing and exercised updates introduced in the newly released Cable OpenOMCI I03 specification. In preparation for the February event, suppliers worked with CableLabs to align the interop test plan with the specification. This updated plan introduced several new validation scenarios intended to:
- Confirm consistent implementation of new I03 requirements.
- Increase overall test plan requirements coverage.
- Better exercise configuration scenarios encountered in member operator deployments.
XGS-PON Interop·Labs Test Plan Evolution
Held at CableLabs headquarters in Louisville, Colorado, the event focused on validating new capabilities introduced in the Cable OpenOMCI I03 specification. The activities exercised the interoperability aspects of the ONU Management and Control Interface (OMCI), defined through ITU-T Recommendation G.988 and the CableLabs Cable OpenOMCI specification.
During the event, OLT and ONU equipment from different suppliers were paired to test various service configurations and monitoring scenarios. Supplier engineering teams arrived with updated software builds and new device variants. Notably, the participants included three suppliers attending their very first CableLabs XGS-PON interop event.
The interop environment provides a unique opportunity for engineers to directly observe how their implementations behave when paired with equipment from other suppliers. These multi-supplier pairings often reveal subtle differences in OMCI behavior that may not be apparent during testing in the supplier’s own facility.
Supplier Participation: A Diverse Ecosystem
We want to thank the supplier participants who contributed to the success of this event. They brought a diverse range of XGS-PON equipment, including both OLTs and ONUs representing multiple device architectures and chipset families. The participating OLT platforms were Calix (E7-2) and Nokia (Lightspan MF-2).
The OLT systems were paired with a broad set of ONUs and PON residential gateways. ONU suppliers were Airoha, Calix, Gemtek, Hitron, Humax, Nokia, RocNet, Sagemcom, Sercomm, Ubee and Vantiva.
The diversity of devices and multi-supplier combinations allowed engineers to exercise how different implementations behaved across numerous ONU-to-OLT pairings.
Testing Environment & Themes
Each OLT supplier operated a dedicated lab setup that included a small-scale PON optical distribution network connecting the OLT platform to one or more ONUs being tested. Engineers relied on OLT debugging tools and an XGS-PON analyzer, provided by CableLabs, to capture OMCI message exchanges and traffic behavior in each scenario.
The testing scenarios were designed to expose differences in device behavior, which enabled engineers to isolate root causes and translate those findings into improvements in both specifications and implementations. Many suppliers demonstrated improvements in areas that had been identified during earlier interoperability events, while the expanded test coverage also uncovered additional behaviors that will guide future specification work.
Key testing scenarios in the February event included:
- Verification of the ONU’s support for the new ONU Time Configuration managed entity, including the ability to set a time-offset-from-UTC value on the ONU and read back the current ONU local time.
- Validation of the ONU’s ability to indicate support for OMCI Extended Message sets via the ONU2-G OMCC Version attribute.
- Testing of the ONU’s support for the use of the Extended Message set during MIB Upload operations.
- Verification of ONU behavior when using the Extended Message set for firmware image downloads.
- Validation of the Extended VLAN Tagging Operation Configuration Data managed entity, including verification of the maximum size of the Received Frame VLAN Tagging Operation Table.
- Execution of a new interoperability test case to exercise upstream traffic handling using DSCP-to-P-bit mapping, classifying traffic flows into specific GEM flows and T-CONTs.
Continuous Improvement Cycle
The CableLabs Common Provisioning and Management of PON (CPMP) working group will now review the findings from this interop. Based on the results collected during the event, the group may generate new requirements that will result in engineering changes to the Cable OpenOMCI I03 specification.
In some cases, the most appropriate path for addressing interoperability issues may involve clarifications or enhancements to the underlying ITU-T Recommendations, such as G.988. The CableLabs CPMP working group is currently developing one such contribution to the ITU-T Study Group 15, Question 2 working group to advance specific clarifications.
This iterative process — combining lab validation, specification updates and standards collaboration — continues to streamline the interoperability of multi-vendor XGS-PON deployments.
More to Come in 2026
Additional PON interop events are scheduled for 2026, as we plan to continue expanding interoperability testing across the ITU-T PON supplier ecosystem.
The next CableLabs XGS-PON Interop·Labs event is planned for June. We expect to exercise the new requirements that are being defined for the forthcoming Cable OpenOMCI I04 specification. We also anticipate hosting another event closer to the end of the year. We look forward to welcoming suppliers back to our Louisville labs as this work continues.
