SFF-8024 — code tables

SFF-8024, SFF Module Management Reference Code Tables, is the shared registry of one-byte codes that every other management specification points to. It does not describe a memory layout; it assigns meaning to values — what module type 18h is, which connector 0Ch means, what extended compliance code 06h stands for. Because the registry lives in one document, SFF-8472, SFF-8636, CMIS, MIS and INF-8077i all interpret the same byte the same way, and new form factors or PMDs are registered once. The document is revised several times a year; always decode against a recent revision.

Where each table is used

Table 4-1 — identifier values

Newer revisions add further CMIS-managed form factors after 21h. Codes 80h–FFh are vendor specific. Which form factor is which: Form factors.

Table 4-2 — encoding

The two columns differ at 04h–06h — a classic source of "wrong encoding" when a QSFP template is reused for an SFP.

Table 4-3 — connector types

Photos and fibre pairings: Connectors & fibre.

Table 4-4 — extended specification compliance (selection)

Used in SFP byte 36 and QSFP byte 192; a single value, not a bit field.

This is the table that makes 25G and 100G identity possible at all: the classic bit fields of SFF-8472 bytes 3–10 have no room for them. How the two mechanisms combine: Compliance codes.

Tables 4-5 onward — CMIS interface IDs (selection)

CMIS describes what a module can do as applications: a host electrical interface paired with a media interface. Both halves are SFF-8024 codes.

Passive copper, active cable and BASE-T media have their own short tables; which table applies is set by CMIS media type byte 85 (01h MMF, 02h SMF, 03h passive copper, 04h active cable, 05h BASE-T). Full lists change with every SFF-8024 revision — treat the above as orientation, not as the registry. How applications are advertised and selected: CMIS.

Practical notes

• A host running older firmware shows codes it does not know as unknown — harmless for reading, but some platforms refuse to bring up a module whose type they cannot name.
• When coding a module, pick the codes that describe the real hardware; hosts cross-check identifier, connector, encoding and compliance against each other (Speed & rate).
• Reserved and vendor-specific ranges (80h–FFh) are legal but decode as nothing useful.

In CodingBox

CodingBox carries the SFF-8024 tables and uses them to label the identifier, connector, encoding, extended compliance and CMIS application fields in the EEPROM editor and on Check transceiver, so a raw 12h in a QSFP-DD application descriptor reads as 400GAUI-8 C2M.

Identifier 21h in practice: OSFP-XD; OSFP at 200G per lane keeps 19h — OSFP224.