Cisco QDD-4X100G-FR-S 400GBASE-XDR4 Optical Transceiver Module

The Cisco QDD-4X100G-FR-S (also referred to as 400GBASE-XDR4 or 400GBASE-DR4+) is a 400G QSFP-DD optical transceiver module designed for high-bandwidth data center and cloud network applications. Its primary function is providing 400Gbps aggregate throughput while supporting breakout capabilities to four 100G links.

Core Technical Specifications
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* Data Rate: 400 Gbps aggregate (8 x 53.125Gbps PAM4 electrical; 4 x 106.25Gbps PAM4 optical).

* Wavelength: 1310 nm.

* Max Reach: Up to 2 km (approx. 1.2 miles) over single-mode fiber (SMF).

* Connector Type: MTP/MPO-12 APC.

* Power Consumption: Typically less than 10W to 10.5W.

* Optical Components: EML transmitter and PIN receiver.

Breakout and Interoperability
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The QDD-4X100G-FR-S is highly versatile due to its parallel fiber architecture:

* Breakout Support: Can break out into 4 x 100G-FR1 links.

* Backward Compatibility: It can be used to connect 400G QSFP-DD switches to legacy 100G QSFP28 switches or server NICs.

* Host FEC: Forward Error Correction is performed on the host platform rather than the module itself.

Standards and Compliance
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* Protocol: Compliant with IEEE 802.3cu (for 100GBASE-FR1) and IEEE 802.3bs.

* Form Factor: Follows QSFP-DD MSA Type 2 standards.

* Management: Supports CMIS 4.0/5.0 and integrated Digital Diagnostic Monitoring (DOM/DDM) for real-time performance tracking.

* Platforms: Primarily used in high-density environments like the Cisco Nexus 9000 series, Catalyst 9600, and NCS 5500 Series.