Wired
Square Pegs, Round Holes and Sandboxes: Working Together for PON Interoperability
Key Points
- Establishing robust interoperability standards for emerging passive optical network (PON) technologies is critical for the broadband industry.
- The Broadband Forum (BBF) provides detailed guidelines and test plans to ensure reliable and consistent interoperability in various network scenarios.
- In partnership with BBF, CableLabs will host a Plugfest event in October to address real-world PON interoperability challenges.
In the world of passive optical networks (PON), achieving seamless interoperability has been a long-standing challenge, leaving operators trying to fit square pegs into round holes. This legacy is largely due to the intentional flexibility in PON standards, designed to foster innovation by avoiding overly prescriptive implementations. However, this flexibility often leaves too much room for interpretation, leading to interoperability issues.
In the PON world, standards like IEEE 802.3, ITU-T G.9807.1 and ITU-T G.9804.3 define operation at the physical layer and data link layer. Similarly, CableLabs’ DOCSIS®️ Provisioning of EPON (DPoE) specifications, IEEE 1904.1 and ITU-T G.988 define operations in the optical network unit (ONU) management layer.
These standards are the starting point for interoperability at these layers. However, the absence of industry cooperation to converge on common interpretations and use cases leads to complex and vendor-specific integrations that add cost to business operations and increase time to market for new products.
DPoE took the specification effort a step further by establishing a certification program that rigorously tests interoperability between ONUs and optical line terminals (OLTs). This program set a precedent, proving that clear, detailed specifications combined with collaborative industry efforts can result in high levels of interoperability across different vendors' PON equipment. The lessons learned from DPoE offer a valuable roadmap for advancing interoperability in the broader PON landscape.
While DPoE's success showcases what is possible, the rapid deployment of XGS-PON — now on the way to being the most widely adopted PON technology globally — underscores that significant challenges remain. With new technologies like 25GS-PON and 50G-PON emerging, the need for robust, consistent interoperability is more pressing than ever.
BBF Test Plans Support Certification Program
The Broadband Forum (BBF) has been instrumental in bridging the gaps left by broad ITU-T PON specifications. Through detailed guidelines and comprehensive test plans, BBF plays a crucial role in driving the industry toward more reliable and consistent interoperability. These test plans cover a wide range of scenarios, including various traffic types, fault conditions and different configurations.
The result of these efforts is the BBF's TR-255 "GPON Interoperability Test Plan," TR-309 "PON TC Layer Interoperability Test Plan" and TP-247 "G-PON & XG-PON & XGS-PON ONU Conformance Test Plan." These specifications are the foundation of the BBF.247 Certification Program.
As part of the BBF.247 Certification Program, vendors submit their equipment to an independent testing laboratory to be tested according to these specifications.
Well over 150 ONUs are certified under the BBF.247 Certification Program. Still, operators experience interoperability challenges. In addition, new technologies like 25GS-PON and 50G-PON are being introduced to the market and have not yet been tested in the BBF.247 Certification Program.
October Plugfest to Help Pave Road to Greater PON Interoperability
To resolve these real-world interoperability concerns and to inform further development of the certification program, it is necessary for the industry to come together in a sandbox environment to test interoperability outside of a formal certification program.
Recognizing the need for hands-on collaboration, the Broadband Forum has reinitiated its PON Plugfest series — an essential platform for the industry to tackle real-world interoperability issues head-on. CableLabs and BBF will host a Plugfest event Oct. 28–Nov. 1 at the CableLabs headquarters in Louisville, Colorado.
The event will provide a collaborative environment where OLT, ONU and test equipment vendors can rigorously test and improve their solutions. Vendors will be paired together for a series of tests to evaluate the level of interoperability between their devices. In turn, the Plugfest will help the industry chart the next phase of interoperability specification development.
While the state of interoperability between OLTs and ONUs has improved, there is still work to be done. The upcoming Broadband Forum PON Plugfest at CableLabs will be a critical opportunity to drive this progress forward.
As the industry gathers at the Broadband Forum PON Plugfest, the path forward is clear: By doubling down on collaboration and embracing certification programs like BBF.247, we can overcome the interoperability hurdles that remain. Together, we will unlock the full potential of PON technologies, ensuring that high-speed, symmetrical broadband reaches every corner of the globe.