Improved host functionality for TWI-based module management
Added ResetL, IntL/TXFaultDD, and ePPS


The SFP-DD MSA (Small Form Factor Pluggable Double Density Multi Source Agreement) announced on the 28th the 4.1 hardware specification and design for the SFF-DD plugging interface applied to high-speed 100+ Gbps high-density networking devices.

The SFP-DD form factor uses a dual-row pluggable module and is backward compatible with SPF+. It also provides enhanced host functionality for module management communications based on the Two-Wire Interface (TWI).

The upgraded SFP-DD 4.1 hardware version includes new features such as ResetL, IntL/TXFaultDD, and ePPS. New timing diagrams display low-speed signals, software control, and module status. The previous "Chapter 7. Management Interface" section has been relocated to "Chapter 4. Electrical Specifications."

The updated hardware specifications specify port mapping, optical connectors, and more. The new release also includes module color coding, which was removed from Chapter 5, "Mechanical Specifications and Board Definitions." TS-1000 module and connector performance standard requirements are included in Appendix A.


Attempts to enable more interaction
The SFP-DD form factor, which aims to support optical modules up to 3.5W, addresses the technical challenges of achieving a double-density interface while ensuring mechanical interoperability with module components produced by different manufacturers, while allowing the continued use of existing SFP modules.

The updated specifications supersede those specified in previous versions, and most notably update the dimensions of mechanical connectors. Industry stakeholders should be aware that the connector dimensions specified in Version 4.1 differ from those of all previous versions.