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Français SFP family hardware specs (INF-8074, SFF-8431…)
The SFP footprint is shared by SFP, SFP+, SFP28 and SFP56, but the documents that define it were written in layers over twenty years. Knowing which layer defines what explains why two modules that look identical behave differently in the same port.
The original MSA
INF-8074 — SFP Transceiver (1.0). The founding SFP agreement: the 20-pin card-edge interface, module outline, the low-speed control signals (TX_DISABLE, TX_FAULT, RX_LOS, MOD_DEF/module-present) and the two-wire identity memory that later became SFF-8472.
Electrical layer (SFP+)
| Document | What it defines |
|---|---|
| SFF-8431 — 10 Gb/s and Low Speed Electrical Interface (4.1) | the SFI high-speed interface, linear vs limiting modules, and the low-speed signalling |
| SFF-8418 — 10 Gb/s Electrical Interface (1.4) | high-speed electrical detail split out of 8431 |
| SFF-8419 — Power and Low Speed Interface (1.3) | supply rails, power classes, low-speed pin behaviour |
| SFF-8461 — Active Cable Specifications (0.2) | active copper/optical cables and their test methods |
Mechanical layer
| Document | What it defines |
|---|---|
| SFF-8432 — Module and Cage (5.2a) | the module and host cage outline used by all SFP-class modules |
| SFF-8071 — 0.8 mm Card Edge Connector (1.9a) | the 20-pin connector |
| SFF-8433 — Ganged Cage Footprints and Bezel Openings (0.7) | multi-port cages on a host board |
| SFF-8075 — PCI Card Version of SFP Cage (1.0) | cages on PCI adapters |
"Transceiver solution" documents by rate
Each bundles the mechanical and electrical requirements for one rate class:
| Document | Class | Rate |
|---|---|---|
| SFF-8084 (1.7) | 4 Gb/s | 4GFC |
| SFF-8083 (3.1) | SFP10 | 10G |
| SFF-8081 (1.4) | SFP16 | 16GFC |
| SFF-8402 (1.1) | SFP28 | 25G / 32GFC |
SFP56 (50G PAM4) builds on the SFP28 definition with the IEEE 802.3cd electrical interface; see SFP56.
Management layer
- SFF-8472 — identity, diagnostics, thresholds (details).
- SFF-8079 / SFF-8089 — rate and application selection and codes (details).
- SFF-8690 — tunable DWDM memory map (details).
Why it matters for coding
Memory fields that CodingBox edits — rate codes, power class, linear/limiting flag, compliance codes — each trace back to one of these documents. When a recoded module does not link, check that what the identity bytes claim (per SFF-8472/8089) matches what the hardware layer actually is (per SFF-8431/8419): a module coded as a power class or interface type it cannot deliver is refused or held in low power by the host.
Source
- sfptotal.ru — List of MSA standards and specifications; SNIA SFF library