Federal Circuit vacates Cisco patent victory, reviving optical networking dispute

The ruling keeps foundational optical networking IP alive, forcing equipment vendors to reassess freedom-to-operate for XPIC-enabled hardware. Because XPIC is essential for maximizing spectral efficiency in dense wavelength-division multiplexing (DWDM), this case directly impacts the competitive perimeter of metro and long-haul transport portfolios. For the broader ecosystem, this vacatur signals an aggressive enforcement landscape led by patent assertion entities targeting core transceiver technologies. Watch for revised claim constructions on remand, which will dictate whether existing optical line cards require new non-infringement arguments.

The dispute centers on whether inventor Dr. Mark Core owned the rights to the '211 patent or if they were automatically assigned to his former employer, TRW Inc. (now Northrop Grumman). Per Justia (May 2024), the Federal Circuit found the 1990 employment contract language—specifically the phrase 'developed entirely on my own time'—was legally ambiguous. This ambiguity stemmed from Dr. Core’s participation in a TRW-funded fellowship while inventing the technology. The vacatur effectively overrules the district court’s summary judgment that had found Core Optical lacked standing to sue.

This litigation is part of a broader campaign by Core Optical that has targeted multiple Tier 1 networking vendors. According to RPX Corporation (February 2021) and World IP Review (May 2024), the patent assertion entity has previously filed infringement claims against Nokia, ADVA Optical Networking, Juniper Networks, and Ciena. Core Optical has specifically accused Cisco’s Network Convergence System (NCS) and ONS series platforms of infringing the '211 patent through devices configured to cancel cross-polarization interference in fiber signals.

Cisco’s renewed exposure in this case adds to its current patent litigation docket. Per a June 2026 report from PatSnap and separate record from August 2024, Cisco recently faced a $65.7 million jury verdict in a lawsuit involving Paltalk Holdings over communications technology. Additionally, in April 2026, the Federal Circuit affirmed a non-infringement ruling for Cisco in a high-stakes case against Centripetal Networks. The remand of the Core Optical case ensures that optical transport remains a high-risk legal category for networking manufacturers through late 2026.