18 September 2017
SFP-DD MSA releases spec for high-speed, high-density interface
The Small Form Factor Pluggable Double Density (SFP-DD) Multi Source Agreement (MSA) Group has completed the initial hardware specification and drawings for the SFP-DD pluggable interface designed to enable high-speed, high-density networking equipment.
Targeting support up to 3.5W optical modules in an enterprise environment, the SFP-DD form factor addresses the technical challenges of achieving a double-density interface and ensuring mechanical interoperability for module components produced by different manufacturers.
SFP-DD MSA founding members include Alibaba, Broadcom, Brocade, Cisco, Dell EMC, Finisar, Hewlett Packard Enterprise, Huawei, Intel, Juniper Networks, Lumentum, Mellanox Technologies, Molex, and TE Connectivity.
The SFP-DD electrical interface expands on the existing SFP pluggable form factor, a widely adopted interface used in data centers and other networking platforms. The SFP single-lane interface operates up to 28Gbps NRZ (non-return-to-zero) or 56Gbps PAM-4 (4-level pulse amplitude modulation). The new SFP-DD electrical interface is designed to support two lanes that operate up to 28Gbps NRZ or 56Gbps PAM-4 per lane, providing aggregate bandwidth of 56Gbps or 112Gbps.
By doubling the lane density and data speed, the SFP-DD interface will help to address demand for increased port density and scalability in next-generation applications, with a primary focus on the server-side interconnect. An SFP-DD server port along with QSFP-DD switch ports provides an overall doubling of the port density in network applications.
The SFP-DD hardware specification and drawings define key module, plug and cage characteristics. SFP-DD modules and direct-attach cable (DAC) plugs use a common mechanical outline. Modules and plugs provide a means to self-lock with the cage upon insertion. Network equipment based on the SFP-DD will support legacy SFP modules and cables, and new double-density products, for optimal design flexibility.
Key SFP-DD features are listed as: a single-port SMT connector and cage; heat-sink options for thermal management flexibility; module mechanical definition; and support for optical and copper interfaces, with physical layer specifications to be determined outside the scope of the SFP-DD MSA.