Optical transceiver standards and specifications

MSA, SFF and CMIS describe different aspects of an optical transceiver. Some documents define the enclosure and connector, others the electrical signals, and others the memory map and module control procedures. To select a specification for programming an SFP, QSFP or OSFP module, first identify the task and the management interface used by that particular transceiver.

This reference helps you find the primary document, understand its purpose and check its revision. The revision numbers below were checked against the publishers' sources on 23 October 2026. A listed document revision does not mean that every module implements it in full: check applicability against the product datasheet and declared capabilities.

What MSA, SFF and CMIS mean

• MSA — Multi-Source Agreement. An agreement among industry participants on compatible product interfaces. There are different MSAs, including SFP and OSFP. An MSA compliant label without a document, revision and supported feature list does not fully describe compatibility.
• SFF is a family of specifications published through SNIA. These include documents on mechanical design, electrical interfaces and management. An SFF number therefore does not by itself identify a firmware format.
• CMIS — Common Management Interface Specification. A common specification for communication between a host and a module: data access, capability advertisement and control. CMIS applies to several form factors and does not define a single mechanical design for them. Published revisions are available from OIF.

These terms are not mutually exclusive. For example, the OSFP MSA hardware specification and CMIS cover different parts of the same product. Compliance with a management map does not guarantee compatibility with every switch: electrical and optical interface, power, cooling and system software limitations still apply.

Three layers: mechanical design, electrical interfaces and management

The memory map is part of the management interface. Its accessible bytes may represent stored identification, live measurements, status or commands. These data are not all freely rewritable EEPROM. The relevant specification and module implementation define address assignments and write conditions.

Memory maps, DDM and management interfaces

Start with this table when reading identification and diagnostics. The form factors listed are typical applications; a module's appearance does not establish which management map it uses.

SFF-8472 is useful for interpreting SFP family identification and DDM. SFP maps use the A0h/A2h notation. These are addresses expressed in the format used by these documents, not universal page numbers for all transceivers. Tools using 7-bit I²C addressing often display the same addresses as 0x50/0x51. Check which notation your tool accepts.

SFF-8636 and CMIS are different management interfaces. Addresses, page numbers and write procedures must not be transferred from one to the other. For multilane modules, also check page selection and, where applicable, bank selection, supported features and module state. Different management implementations can occur even within closely related QSFP families.

SFF-8024 contains common code tables, such as module and connector type identifiers. It helps interpret a field value, but does not replace the document that defines the field's address and meaning in a particular map.

SFP, QSFP and OSFP hardware specifications

These documents support hardware interface selection and design. A solution specification links requirements and references across several documents; it does not replace all detailed drawings, electrical parameters or the management map.

For QSFP-DD, obtain hardware requirements from the relevant MSA, and management requirements from the applicable CMIS revision and module documentation. The OSFP hardware document explicitly separates CMIS management from mechanical, electrical and thermal requirements. Neither a shared management interface nor a similar purpose makes OSFP and QSFP-DD mechanically interchangeable.

Early comprehensive specifications and MSA documents

These document numbers often appear in datasheets and older instructions. They are retained here to help interpret the original product requirements. Read their status and scope together with the revision number.

SFF-8431 is an archived document. Its cover explicitly identifies SFF-8419 for the low speed interface and SFF-8418 for the remaining 10G electrical requirements. SFF-8431 must therefore not be presented as the sole current source for all SFP+ parameters.

SFF-8436 is a comprehensive QSFP+ 4×10 Gb/s specification. For other QSFP generations, also check SFF-8665, the electrical interface profile and the selected management map. SFF-8679 states that it replaces the base electrical portion of SFF-8436; SFF-8636 separately describes four-lane module management.

The earlier collection listed CMIS 5.0. To find published revisions, now use the OIF catalog, Management Interface Specifications section. The revision verified there is CMIS 5.4, May 2026. This does not require using 5.4 with a module designed for another revision.

Selecting a specification for reading or changing memory

1. Identify the product. Record the form factor, part number and hardware revision. Check the module datasheet and the operations supported by the coding board.
2. Identify the management interface. Use the documentation and the identification data read from the module; a speed designation alone is insufficient. Select SFF-8472, SFF-8636, CMIS or another explicitly specified document.
3. Record the revision. Compare the title page number, change history and the module's declared support. The website update date may differ from the specification date.
4. Check the required field. Establish the address, page/bank, units, read and write permissions, access conditions and whether the feature is mandatory. For an encoded field value, consult the relevant SFF-8024 table.
5. Save the original data. Back up accessible areas before making changes. Check the applicable checksums and read the data back after writing. Protected and service areas must not be treated as an ordinary editable buffer.

For example, interpreting SFP Serial ID and DDM requires the SFF-8472 map and code tables. Checking cage dimensions requires a hardware specification. If a module uses CMIS, selecting addresses from an SFP memory table is incorrect even when the required field has a similar name.

Neither changing the standard number in a description nor writing another identifier into memory adds an unsupported physical speed, optical type or power capability to a module. Code compatibility and actual link operation must be verified separately.

Additional documents from the original collection

The links below retain the other documents from the original list. No current revision number is claimed here: check the title page and status in the SNIA catalog.

• SFF-8662
• SFF-8682
• SFF-8672
• SFF-TA-1004
• SFF-8663
• SFF-8683
• INF-8628: search the SNIA catalog
• SFF-8635
• SFF-8685
• INF-8438
• INF-8476
• INF-8474
• SFF-8071
• SFF-8461
• SFF-8084
• SFF-8083
• SFF-8081
• SFF-8690
• SFF-8433
• SFF-8089
• SFF-8079
• SFF-8075

SFF-TA-1004 at the retained link is designated Development 0.0.10 dated 23 January 2018. It is a draft extension for managing tunable QSFP+/QSFP28 modules, not a published universal configuration standard for all modules. Likewise, a file's presence in the catalog does not mean that your product implements all of its functionality.

Checking document revision and status

• Published in the SNIA catalog indicates a document approved for publication; Draft indicates a draft for review. Expired means maintenance has ceased; consult the cover for the reason.
• Read the number and date inside the PDF. A permanent publisher URL may start serving a newer revision, making an older label saved beside it inaccurate.
• Use the OIF catalog for CMIS and the relevant group's website for MSA specifications. Do not determine currency solely from a filename in a third-party collection.
• Match the revision against the module datasheet. A new document revision does not automatically update devices already manufactured.

This reference does not replace the primary specifications. The tables above help locate documents by purpose; read the appropriate document revision for exact field values, timing parameters and requirements.

Related SFPTotal guides

• Coding board form factors and capabilities : module families supported by SFPTotal models.
• Transceiver memory structure : how Wizard presents memory areas.
• Reading memory and backing up : preparing data before editing.
• DDM diagnostics interface : reading measurements and thresholds in Wizard.
• Checksum verification : commands for checking supported checksum fields.