The Quad Small Form Factor Pluggable Double Density (QSFP-DD) Multi Source Agreement (MSA) group has released a specification for the new QSFP-DD form factor, which is a next generation high-density, high-speed pluggable module with a QSFP28 compatible double-density interface. QSFP-DD pluggable modules can quadruple the bandwidth of networking equipment while remaining backwards compatible with existing QSFP form factors used across Ethernet, Fibre Channel and InfiniBand for 40 Gbps and 100 Gbps network applications.

In total, 52 companies came together in support of the QSFP-DD MSA to address the industry need for high-density, high-speed networking solutions.
QSFP-DD MSA founder-promoters include Broadcom, Brocade, Cisco, Corning, Finisar, Foxconn Interconnect Technology, Huawei, Intel, Juniper Networks, Lumentum, Luxtera, Mellanox Technologies, Molex, Oclaro, and TE Connectivity.
Contributors include Amphenol, Applied Optoelectronics, APRESIA Systems, Celestica, Ciena, ColorChip, Dell EMC, Delta, Fujitsu Optical Components, Genesis, H3C, Innovium, Inphi, Ixia, Kaiam, LEONI, Lorom, Luxshare, MACOM, MaxLinear, MultiLane, NeoPhotonics, Nokia, Panduit, PHY-SI, Ranovus, Samtec, Senko, Semtech, Sicoya, Siemon, Skorpios Technologies, Source Photonics, Spirent, Sumitomo Electric, Xilinx, and Yamaichi Electronics.
http://www.qsfp-dd.com/