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Bahasa Melayu QSFP-DD
Đội ngũ của chúng tôi đang thực hiện bản dịch. Bài viết này tạm thời chưa có bản tiếng Việt và đang được hiển thị bằng tiếng Anh.
QSFP Double Density (QSFP-DD) adds a second row of contacts to the QSFP connector, doubling the lanes to eight while keeping the QSFP faceplate footprint. It is the dominant 400G form factor and, as QSFP-DD800, a leading 800G one — and its cage still accepts every earlier QSFP module.
Key facts
| Lanes × rate | 8 × 50G (PAM4) → 400G; 8 × 100G (PAM4) → 800G (QSFP-DD800) |
| Total | 400G / 800G |
| Connector | MPO-12/MPO-16 (DR4/DR8/SR8), LC duplex (FR4/LR4), CS/SN duplex (2×FR4), DAC/AOC |
| Supply | 3.3 V; power classes up to ~14 W and above with enhanced cooling |
| Applications | 400GBASE-DR4/FR4/LR4/SR8, 800G-DR8/2×FR4, AI/ML fabrics, 2×200G / 4×100G / 8×50G breakout |
Specifications
- INF-8628 — QSFP-DD 8X Transceiver (Double Density): the QSFP-DD MSA hardware specification (mechanical, electrical, thermal).
- QSFP-DD800 — the MSA revision defining 100G-per-lane operation.
- CMIS 5.0 — Common Management Interface Specification (management). See CMIS.
Management interface
QSFP-DD is the form factor for which CMIS was created. The host drives a module state machine (ModuleLowPwr → ModulePwrUp → ModuleReady) and per-lane data-path states, selects an application from the module's advertised list, and reads banked pages for identity, diagnostics and configuration. Extended operations — firmware update, tuning — go through the CDB command interface. Codes are from SFF-8024.
Because so much depends on the handshake, "module stuck in low power" and "recognised but not ready" are the typical QSFP-DD failures — see CMIS issues.
Compatibility notes
- Backward compatible cage: a QSFP-DD port accepts QSFP112, QSFP56, QSFP28 and QSFP+ modules on four of its eight lanes.
- Breakout options: 2×200G, 4×100G, 8×50G depending on the module PMD.
- The competing eight-lane form factor is OSFP — larger, with an integrated heat sink; the two are not mechanically interchangeable.
In CodingBox
CodingBox supports QSFP-DD through CMIS 4.0/5.0: module state, identity, applications, per-lane DDM and configuration pages are decoded and editable, with per-lane values on the DDM screen revealing a single failed lane out of eight.
On the OSFP side the step to 1.6T is taken by OSFP224 and OSFP-XD; QSFP-DD800 and QSFP-DD1600 are the QSFP-DD MSA's counterparts.