25 May 2021
QSFP-DD MSA announces HW Spec 6.0, CMIS 5.0 and thermal design whitepaper
The Quad Small Form Factor Pluggable Double Density (QSFP-DD) Multi Source Agreement (MSA) group has released a hardware specification revision 6.0 updating QSFP-DD, introducing both QSFP-DD800 and QSFP112.
QSFP-DD is the premier 8-lane data-center pluggable module form factor. Systems designed for QSFP-DD modules can be backward compatible with existing QSFP form factors and provide maximum flexibility for end users, network platform designers, and integrators. With the inclusion of support for 100Gb/s electrical host interfaces, this seventh public release adds QSFP-DD800 and QSFP112 Mechanical and Board Definitions. It also adds QSFP112 electrical and management timing. Revision 6.0 includes updated power supply test methods and support for an increased module power rating to 25W. The module power contact rating is increased from 1A to 1.5A. An appendix with normative connector performance data has also been added.
The group has also announced the release of an updated Common Management Interface Specification (CMIS) revision 5.0 for QSFP-DD, QSFP-DD800 and QSFP112. The CMIS defines the host-to-module interactions needed to ensure that modules will initialize and operate consistently. This revision provides several extensions and a comprehensive technical and editorial consolidation. It is harmonized with timing parameters defined in QSFP-DD MSA HW Spec revision 5.1 previously published and in this revision 6.0. CMIS is broadly implemented across the industry, beyond just the QSFP/QSFP-DD family of module types. The feedback from many implementers has also been consolidated to improve and extend the specification.
“It is exciting to see how the 63 companies involved came together to harmonize these important QSFP/QSFP-DD form factors and software to future-proof data centers while maintaining backward compatibility,” says Scott Sommers, MSA co-chair & founding member.
The MSA group has also announced the release of a new thermal management whitepaper. High-performance network environments need efficient cooling of pluggable optical modules. This is particularly true for the new high-power 25W modules for QSFP-DD800 systems, which must dissipate heat effectively to ensure operational performance. Careful thermal design of module, cage, heatsink and the overall system for QSFP-DD modules is required for efficient heat dissipation. The new whitepaper explains techniques that can be used to achieve this goal in QSFP-DD/QSFP-DD800 module design and QSFP-DD/QSFP-DD800 system design. It includes both experimental and simulation studies to demonstrate the efficacy of these techniques.
“The performance and power demands for high-speed network solutions are constantly increasing,” says Mark Nowell, MSA co-chair & founding member. “This whitepaper captures the design experience garnered over the recent years from many companies and was written to help design engineers understand how they can achieve the thermal characteristics their system requires, even when using new 25W modules, thus ensuring the reliable operation of their products.”