Arista QDD-SR8-800G Compatible LINK-PP 800GBASE-SR8 QSFP-DD 850nm 50m MPO-16/APC DOM 8 x 100G PAM4 MMF Transceiver Module

Product Specifications

Arista QDD-SR8-800G Compatible LINK-PP LQD-DM85800-SR8C 800GBASE-SR8 QSFP-DD Optical Transceiver 850nm 50m MTP/MPO-16 APC for Arista AI/ML Networks

The LINK-PP LQD-DM85800-SR8C is an ultra-high-capacity, Arista QDD-SR8-800G compatible 800GBASE-SR8 QSFP-DD optical transceiver engineered specifically for next-generation AI/ML backend fabrics, High-Performance Computing (HPC) clusters, and hyperscale data center core networks. Operating over multi-mode fiber (MMF), this hot-pluggable module delivers unparalleled bandwidth density to eliminate network bottlenecks in GPU-accelerated computing environments utilizing Arista's high-throughput routing platforms.

Integrating eight parallel transmission and receiving lanes utilizing 100G PAM4 (Pulse Amplitude Modulation 4-level) electrical and optical signaling, the module achieves an aggregate data rate of 850Gbps (8x 106.25Gbps). Fully compliant with the latest IEEE 802.3df-2024 and IEEE 802.3ck standards, QSFP-DD MSA Hardware Rev 7.0, and CMIS 5.0, it ensures pristine signal integrity up to 30m on OM3 and 50m on OM4 fiber. Built as a direct, seamless alternative to OEM Arista optics, it equips data center architects with a reliable, cost-effective building block for scaling 800G Ethernet infrastructures.

Application Topologies and Deployment Scenarios

The shift to 800G Ethernet is driven by the massive I/O demands of generative AI, large language models (LLMs), and deep learning workloads. This QSFP-DD module is optimized for short-reach, extreme-throughput connectivity within high-density Arista data center environments.

AI/ML GPU Cluster Fabrics and Backend Networks

In large-scale AI training clusters, compute nodes equipped with 800G NICs require non-blocking, microsecond-latency interconnects. The 800G QSFP-DD SR8 is the standard deployment choice for connecting AI server nodes directly to 800G Top-of-Rack (ToR) or leaf switches (such as the Arista 7060X5 series), forming a lossless Ethernet backend fabric capable of handling massive East-West RDMA (RoCEv2) traffic.

Hyperscale Spine-Leaf Core Aggregation

For cloud service providers upgrading their Clos topologies, this module serves as the primary high-speed uplink bridging 800G leaf switches to 800G spine/super-spine routers (such as the Arista 7800R3 or 7700R4 Series). It dramatically reduces the number of required physical links and transceiver ports compared to aggregating multiple 400G links, saving critical rack space, reducing fiber count, and lowering power consumption per bit.

800G Breakout to 2x 400G or 8x 100G Configurations

Port density optimization is a major use case for parallel 800G optics. By utilizing specialized MTP-16 breakout cables, a single 800G QSFP-DD switch port can be fractionalized. Network architects can deploy it as 2x 400GBASE-SR4 (connecting to two 400G switches) or 8x 100GBASE-SR/VR (connecting directly to eight 100G servers), making it a highly versatile tool for high-density Top-of-Rack aggregation.

Physical Layer Design and Optical Performance Optimization

Transmitting 100Gbps per lane over multi-mode fiber pushes the physical limits of VCSEL technology. LINK-PP transceivers integrate state-of-the-art optical engines and DSP (Digital Signal Processing) to ensure a zero-packet-loss physical layer.

8x 100G PAM4 VCSEL Array Architecture

Unlike legacy NRZ signaling, PAM4 transmits two bits per symbol via four distinct voltage/optical power levels. The transmission core utilizes an advanced 850nm VCSEL array optimized for 106.25Gbps baud rates. This requires extraordinary linearity and exceptionally low Relative Intensity Noise (RIN). The receiving end utilizes a matched high-bandwidth PIN array to accurately decode the complex PAM4 optical eye diagram.

The MTP/MPO-16 APC Connector Interface

To support 8 TX and 8 RX lanes, this transceiver uses an MTP/MPO-16 connector. More importantly, to handle the extreme sensitivity of 100G PAM4 signals to optical return loss (reflection), this multi-mode transceiver utilizes an APC (Angled Physical Contact) interface. The 8-degree polish ensures that any reflected light is directed into the fiber cladding rather than bouncing back into the VCSEL laser cavity, preserving signal integrity.

Advanced Thermal Management and QSFP-DD Housing

800G transceivers process massive amounts of data, drawing significantly higher power than 100G/400G legacy modules. This unit is engineered within a QSFP-DD Type 2/2A housing featuring premium die-cast thermal pads. It dissipates heat efficiently away from the DSP and optical sub-assemblies, ensuring stable operation up to 70°C without forcing modern 800G Arista switch chassis fans into thermal runaway.

Multi-Vendor Compatibility and CMIS 5.0 Diagnostics

Managing an 800G fabric requires advanced software interfaces. This transceiver supports the latest Common Management Interface Specification to provide unprecedented visibility into the link state.

Arista Compatibility and CMIS Rev 5.0 Management

Undergoing rigorous EEPROM coding and hardware validation, this module is natively recognized as an Arista QDD-SR8-800G. It guarantees plug-and-play interoperability in switches currently running Arista EOS (Extensible Operating System), as well as MSA-compliant 800G platforms. Furthermore, compliance with CMIS 5.0 provides a robust state machine for module initialization, allowing the host switch to negotiate power classes and datapath configurations before laser activation.

Per-Lane Real-Time Telemetry

Network engineers can actively monitor the health of all 16 parallel channels (8 TX / 8 RX). Telemetry includes independent TX Bias Current, TX Optical Power, and RX Optical Power for every individual lane. This granular visibility is absolutely critical in AI fabrics, where a single degraded optical lane can throttle an entire GPU training cluster.

Selection Guide and Deployment Considerations

Deploying 800G PAM4 optics introduces strict new cabling rules that differ vastly from legacy 40G/100G networks. Follow these critical guidelines to prevent hardware damage and link failures.

The MTP/MPO-16 APC Cabling Requirement (Crucial)

This is the most common deployment mistake in 800G networks. Legacy MMF MPO cables (like those used for 100G SR4 or 400G SR8) are typically PC/UPC (flat-polished) and often MPO-12 or MPO-24. You MUST use an MTP/MPO-16 APC (Angled) cable for this 800G transceiver. Forcing a flat UPC MTP cable into this module will physically crush the internal lens array and permanently destroy the transceiver.

Mandatory Host-Side FEC (Forward Error Correction)

PAM4 modulation at 106.25Gbps per lane inherently produces bit errors before correction. The 30m/50m reach of this transceiver is strictly dependent on KP4 FEC (Clause 91 / Clause 119) being enabled on the host switch port. Operating this module without host-side FEC is not supported and will result in massive packet loss and link failure.

Distance Limits and Fiber Types

Due to the severe chromatic dispersion and modal bandwidth limits of MMF at 100G/lane baud rates, maximum distances are strictly limited to short reaches:

• OM4 Multimode Fiber: Up to 50 meters (Max supported distance for 800GBASE-SR8)
• OM3 Multimode Fiber: Up to 30 meters
• Connector Type: MTP/MPO-16 APC (Ensure patch cables are explicitly verified for 8-degree APC MMF)