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PON Event Continues to Explore and Evolve Equipment Interoperability
Key Points
- This summer’s CableLabs PON Interop·Labs event brought together OLT and ONU suppliers to test the device interoperability aspects of the I02 version of the Cable OpenOMCI specification.
- This was the latest in a series of events hosted by CableLabs as part of our quest to build a healthy, diverse and interoperable XGS-PON supplier ecosystem.
The latest CableLabs Interop·Labs CPMP XGS-PON event took place Aug. 4–7 in our Louisville, Colorado, labs and was designed to test the ONU Management and Control Interface (OMCI). The event focused on exercising a core subset of the OMCI requirements defined by a combination of the ITU-T Recommendation G.988 and CableLabs’ Cable OpenOMCI specifications. For background on the importance of OMCI interoperability testing and the genesis of the Cable OpenOMCI specification, please see my blog post, “Driving Alignment: New Progress Toward XGS-PON Equipment Interoperability” (May 2025).
This was the second interop event at which we tested the OMCI layer via pairings of optical line terminals (OLTs) and optical network units (ONUs) from various suppliers. And for this event, supplier engineers executed test cases designed to exercise requirements from the I02 version of the Cable OpenOMCI specification, published in July 2025.
Supplier Participation at the XGS-PON Interop
For the August event, we hosted an array of ONU suppliers, who brought a variety of devices to test. These suppliers and devices included:
- Calix — ONU and gateway
- Ciena — multiple ONU models
- Comtrend — ONU
- Hitron — ONU
- Nokia — multiple ONU models
- Sagemcom — ONU and gateway
- Ubee — multiple gateway models
Also for this event, we hosted our largest number of OLT suppliers yet. OLT suppliers on hand were:
- Calix — AXOS E7-2 OLT
- Ciena — Tibit MicroPlug OLT
- Harmonic — Pier OLT
- Nokia — Lightspan MF-2 OLT
Some of the OLT suppliers also made use of their DOCSIS Adaptation Layer capabilities to help streamline ONU service provisioning in the lab.
Interop Test Plan Evolution
For the interoperability event, the test setup was duplicated on each participating OLT supplier workbench. A small-scale PON optical distribution network (ODN) was built on each workbench, connecting the supplier’s OLT to one or more ONUs under test. The OLT supplier made use of its OLT’s logging and debugging capabilities or the lab’s XGS-PON analyzer equipment to record the results of each OMCI test case.
Interested participating suppliers met a few weeks in advance of the event to update the test plan, based on changes from the I02 specification and from lessons learned from previous events. In addition to the five test cases described in my May blog post, the interop test plan for this event was extended to include test cases for ONU time synchronization and access network interface optical power levels.
Overall results from the interoperability events continue to be encouraging. Suppliers have taken lessons learned from previous events and made improvements to their software implementations. Testing at this particular event showed the resolution of previous issues but also uncovered new ones.
Continuous Improvement Cycle
As a next step, the CableLabs CPMP working group will discuss the findings from this event and, if necessary, define solutions for those issues in the form of engineering change requests against the published Cable OpenOMCI I02 specification.
Once significant engineering changes have been incorporated into that version, we’ll issue an I03 version of the spec. In some cases, the working group may determine that a discovered issue would be best addressed in the ITU-T space. In those cases, a working group member company will deliver a proposal to the ITU-T Study Group 15, Question 2 working group for consideration as a change to G.988.
See You In November
CableLabs is planning another PON Interop·Labs event the week of Nov. 3. Details of that event will be made available as we get closer to that week.
We plan to welcome OLT and ONU suppliers back to our lab to exercise the interoperability aspects of the I03 version of the Cable OpenOMCI specification. We expect to have an updated interop test plan (based on the I03 version) available to participants in advance of the November event.