Cisco QDD-400G-DR4 400G QSFP-DD DR4 Transceiver, 1310 nm, 500 m over Single-Mode Fiber: This is a Cisco-branded 400 Gigabit Ethernet (400GbE) optical transceiver in the QSFP-DD form factor, implementing the IEEE 400GBASE-DR4 specification. Optical output is delivered through an MPO-12 connector over four parallel single-mode fibers; this is not an SR8 multimode part and not a passive DAC. This is a refurbished unit.
Engineering Context
The QDD-400G-DR4 carries 400 Gb/s as 4 lanes of 100 Gb/s PAM4 over four parallel single-mode fibers in each direction, at a center wavelength of 1310 nm. It targets up to 500 m of reach as defined by IEEE 400GBASE-DR4. Digital Diagnostic Monitoring (DDM/DOM) is supported, exposing per-lane optical power, temperature, and bias current to the host switch. The QSFP-DD package is electrically backward-compatible with QSFP+/QSFP28 cages but requires a host port that explicitly supports 400G QSFP-DD optics.
Deployment & Use Cases
400GbE leaf-to-spine and spine-to-spine interconnects in hyperscale and enterprise data centers. Native 400G server uplinks feeding GPU and AI training clusters where multimode reach is insufficient. Data center interconnect (DCI) within campus distances. Migrations from 100GbE PSM4 fiber plant to 400GbE using existing parallel single-mode infrastructure where lane breakout is supported by the switch ASIC.
Technical Specifications
OEM: Cisco
Part Number: QDD-400G-DR4
Form Factor: QSFP-DD
Data Rate: 400 Gb/s (4 × 100G PAM4)
Wavelength: 1310 nm
Fiber Type: Parallel Single-Mode Fiber (SMF)
Connector: MPO-12
Maximum Reach: 500 m
Standard: IEEE 400GBASE-DR4
DDM/DOM: Supported
Laser Class: Class 1
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Constraints
Requires a Cisco host platform whose port explicitly supports the QDD-400G-DR4 in its compatibility matrix; the QSFP-DD electrical interface is backward-compatible with QSFP+/QSFP28 cages, but 400G operation needs a 400G-capable port. Use single-mode parallel MPO-12 patch cords (APC or UPC per the host requirement); not interoperable with multimode SR8 (MMA4Z00-NS) or duplex single-mode FR4/LR4 modules. Lane breakout to 4 × 100G or 4 × 100GBASE-DR depends on the switch ASIC and software release. This is a Class 1 laser product — handle with eye-safety practices.
Why TES
T.E.S IT-SOLUTIONS bench-tests every transceiver for per-lane optical power, DDM telemetry, and link establishment before shipment. Visit tes-itsolutions.com for compatibility advice on Cisco platforms, full warranty terms, and 1–3 day handling on in-stock units.