25GS-PON MSA releases version 4 with quantum-safe encryption and Combo-PON support

The 25GS-PON MSA Group has released version 4 of its 25GS-PON specification, adding quantum-safe AES-256 security, Combo-PON module support and new optical budget options. The update is meant to improve deployment flexibility and performance as the MSA grows to 68 member organizations.

Why it matters: - Version 4 adds security, capacity and deployment features aimed at making 25GS-PON easier to roll out in more fiber networks. - The update also pushes 25GS-PON closer to broader commercial use by improving coexistence with other PON generations. - The MSA now counts 68 member organizations, signaling continued industry backing for 25G symmetrical passive optical networking. - More information is available in the Resources section of the 25GS-PON MSA website.

What happened: - The 25GS-PON Multi-Source Agreement Group released and published version 4 of the 25GS-PON specification on June 16, 2026. - The update includes changes in security, Combo-PON modules, deployment flexibility and performance. - The full specification is publicly available in the Resources section of the 25GS-PON MSA website.

The details: - The new specification introduces AES with a 256-bit key for quantum-safe encryption and stronger protection against brute-force attacks. - The security upgrade aligns 25GS-PON with the security level of 50G PON. - Version 4 explicitly supports Combo-PON modules, allowing XGS-PON and 25G PON to operate on the same network infrastructure. - Two new optical budget classes were added: B+ at 28 dB and D at 35 dB. - The added classes are intended to extend network reach and capacity across different deployment scenarios. - Upstream optical path loss budgets were added for E1 and E2 classes, completing symmetrical downstream and upstream specifications for non-Combo PON use cases. - The specification adds a narrowband upstream wavelength option centered at 1300 nm with a width of ±2 nm. - The narrower wavelength improves OLT receiver sensitivity and supports higher optical path losses. - The wavelength option also aligns with ITU-T standards for spectral usage. - A new upstream wavelength and tolerance indication feature lets the OLT notify ONUs of permitted wavelengths and tolerances. - The new feature is designed to improve coexistence with other PON generations and reduce interference. - The minimum extinction ratio for OLT transmitters was relaxed from 8 dB to 7 dB to simplify deployments.

Between the lines: - The release shows the 25GS-PON MSA is moving from basic standard-setting toward practical deployment refinement. - The mix of security, coexistence and optical-budget changes suggests the group is targeting operators that need faster upgrades without replacing existing fiber plant. - The focus on Combo-PON support is a sign that multi-technology networks remain central to real-world broadband buildouts.

What's next: - The 25GS-PON MSA says version 4 is intended to help drive innovation in fiber networks and support higher-speed broadband services worldwide. - Operators and vendors can now use the published specification as the reference point for implementations and product planning. - More information or membership details are available here.