The members of the Quad Small Form Factor Pluggable Double Density Multi Source Agreement (QSFP-DD MSA) Group have released preliminary hardware specifications, including drawings, for the new optical transceiver form factor. Announced this past March, the QSFP-DD aims to leverage the four-lane QSFP pluggable form factor electrical interface to support transmission of 200 or 400 Gbps (see "QSFP-DD MSA targets 200G, 400G optical transceivers"). The group also expects the optical module to be interoperable and backward compatible with the current QSFP+/QSFP28 form factors.
The QSFP-DD specifications include eight lanes of up to 25 Gbps via NRZ modulation or 50 Gbps via PAM4. The size of the device should enable 36 QSFP-DD modules to fit in a single switch slot, providing up to 14.4 Tbps of aggregate capacity.
The 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.
The preliminary hardware specification defines module, plug, and cage characteristics. A common mechanical outline is used for QSFP-DD modules and direct-attach cable plugs. Modules and plugs will be able to self-lock with the cage upon insertion. QSFP+/QSFP28 modules and cables may be plugged into and operate in the new QSFP-DD port as well.
Other QSFP-DD specification details include:
- A dual-port integrated connector in a 2×1 stacked cage
- A single-port SMT connector and cage
- Each QSFP-DD port provides 76 electrical contacts
- New modules with heat sink options for thermal management flexibility.
The QSFP-DD preliminary hardware specifications are available for download at www.qsfp-dd.com. Mechanical samples will be available from some respective member companies (the MSA group didn’t release a list of these companies).
Work on the full specification should finish by early 2017. The group continues to welcome interested parties to join as Contributor members.
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