DSFP

Dual Small Form-factor Pluggable (DSFP) puts two electrical lanes into a module with the mechanical dimensions of an SFP. With 2 × 50G PAM4 that is 100 Gb/s per port — the same goal as SFP-DD, reached by a different route: DSFP keeps a single row of contacts and adds pins to it, where SFP-DD adds a second row.

Key facts

Specifications

• DSFP MSA Module Hardware Specification, Rev 1.0 (September 2018) — electrical, mechanical and thermal requirements for the module and the host: connector, cage, power and hardware I/O. Founding members: Amphenol, Finisar, Huawei, Lumentum, Molex, NEC, TE Connectivity and Yamaichi.
• DSFP MIS — the management interface: an abridged version of CMIS, in the same family as the SFP-DD MIS.

Management interface

DSFP does not use the SFF-8472 two-address model of SFP. Like other CMIS-derived interfaces it has lower memory that is always accessible, paged upper memory and per-lane monitoring and control, cut down to two lanes. The identifier byte 1Bh tells the host — and CodingBox — which layout to apply.

Compatibility notes

• The MSA keeps the SFP mechanical dimensions and aims at interoperation with existing SFP modules and cables. The second lane uses additional and reassigned contacts, so whether a given DSFP port accepts ordinary SFP/SFP28 modules depends on the host design — check the equipment documentation.
• DSFP and SFP-DD are not interchangeable: they solve the same problem with different connectors and different management specifications.
• DSFP is found mainly in wireless (5G) equipment and in some 100G network adapters; in switches and data centres SFP-DD and QSFP28 are more common for 100G.

In CodingBox

CodingBox recognises DSFP modules by the identifier 1Bh and decodes them with the CMIS-derived layout — identity, per-lane diagnostics and configuration pages — rather than the SFF-8472 map used for single-lane SFP modules.