FRANKFURT--As the ECOC 2024 trade show gets underway in Frankfurt, Germany, the LPO MSA (Linear Pluggable Optics Multi-Source Agreement) Group recently achieved interoperability testing of network equipment leveraging LPO links.
During the interop event, group members tested 400 Gbps and 800 Gbps parallel single-mode links, targeting the industry-wide challenge of reducing power, cost, and latency while improving the reliability of high-speed optical interconnects in AI/ML applications.
Jointly hosted by MultiLane and Keysight Technologies, the event validated the LPO MSA draft specification and allowed companies to confirm interoperation.
According to the LPO group, the interop event achieved margins above link budget requirements while interfacing with an ecosystem of link partners. The event included test point validation and complete link testing, demonstrating a significant system margin.
“Linear optics is an important tool for increasing the performance of AI training and inference systems while simultaneously decreasing TCO,” said Peter Del Vecchio, LPO MSA Co-Chair. “The successful multi-party interoperability test, based on the draft LPO MSA specification, is an important step in demonstrating to the industry that LPO can be deployed at scale with a broad ecosystem of optical modules and networking components.”
Focus on diagnostics
Another critical area that the LPO MSA group is focused on is diagnostics.
One of the LPO MSA’s initial moves to address the industry’s request for diagnostic information commensurate with retimed links was to create a white paper.
This white paper shows a full suite of capabilities for LPO link monitoring and analysis leveraging diagnostic capabilities already integrated within components along the signal path.
Network equipment that includes Linear Pluggable Optics (LPO) modules and host ASICs provides a full suite of link monitoring and analysis capabilities by leveraging diagnostic capabilities integrated within components along the signal path.
When the LPO MSA asked for input on what issues were at the top of the mind to diagnose, it noted three prominent cases: poor fiber connections, laser aging, and multipath interference (MPI).
If an ASIC reports a high bit error rate (BER) or poor signal-to-noise ratio (SNR), a technician could check if the input swing to the ASIC from the LPO module is appropriate. The white paper suggests that if the link has a poor fiber connection, the output swing from the TIA may be lower than expected.
The white paper pointed out that service providers can monitor the health of a transmit laser within LPO modules in the same way as retimed modules. In the case of an aging laser, the laser aging case, an LPO module would generate an alarm based on an Optical Power Low flag to alert the network of a reduction in output power.
Multipath Interference (MPI) occurs when optical reflections are present in a fiber link. Common culprits contributing to this issue could be not adequately mated connectors and unclean fiber interfaces at the connector. Further, the transmit and receive LPO modules may report that the signals for the respective ends of the link are at appropriate levels.
Next steps
With the interop event now complete, the LPO MSA is plotting its next steps. The group has drafted interop requirements and is looking to attract new members.
Taking a page from other industry standards such as IEEE 802.3 and OIF, the LPO MSA has drafted component, module, and system-level interoperability requirements that span both the electrical and optical interfaces operating at 100 Gbps per lane.
Given the group's initial progress in creating an initial LPO MSA specification, the LPO MSA is announcing that it is now open to new members.
Today, the LPO MSA members include Accelink, AMD, Arista, Broadcom, Bytedance, Cisco, Eoptolink, Hisense, Intel, Keysight Technologies, MACOM, MultiLane, NVIDIA, and Semtech Corporation.
The expanded membership will help it achieve two new goals: improve the initial specification, enable a broad ecosystem for 100G/lane LPO solutions, and guide the next round of specifications, including multi-mode optics, LRO (Linear Receive Optics), and 200G/lane solutions.
The LPO market is showing some potential.
A recent QYResearch report forecasts that the global LPO market will grow from $21.2 million in 2023 to $2 billion in 2029.
Still, Light Counting noted in the ninth edition of its Silicon Photonics report market growth will be evolutionary. “Conventional re-timed pluggables will continue to dominate the market for the next five years, and probably longer than that,” Light Counting noted in its report. “However, LPO/CPO ports will account for more than 30% of the total 800G and 1.6T ports deployed in 2026-2028.”
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