I. Preface

With the continuous expansion of AI computing clusters, 800G optical modules can no longer meet the demands of high-density networking. 1.6T optical modules have become core devices for GPU interconnection and data center backbone networking. The products comply with the IEEE 8×212.5Gbps PAM4 standard, and are divided into two optical path variants: short-reach DR4 and medium-reach FR4, paired with three package types: standard OSFP, OSFP224, and OSFP-XD. The following provides a concise analysis of their parameters and selection guidelines.

II. Core Technical Foundation of 1.6T Optical Modules

1.6T modules adopt 212.5G PAM4 signaling paired with silicon photonic optical engines, with a built-in DSP for signal shaping and error correction. They support 800G/1.6T dual-mode switching to enable smooth network upgrades.

Power consumption grades are clearly defined:

• Standard OSFP: typical power consumption of 20–26W
• OSFP224: optimized heat dissipation, with power consumption of 16–18W
• OSFP-XD: heat dissipation upper limit of over 25W, suitable for high-power applications such as coherent optics

1.6T OSFP 2×DR4 500m

III. Comparison of DR4 and FR4 Optical Path Solutions

Mainstream 1.6T optical modules fall into two categories: short-reach parallel DR4 and medium-reach wavelength-division FR4, each adapted to different networking scenarios. The core differences are as follows:

1.6T OSFP-XD 2×FR4 2km

IV. Core Analysis of Three Package Formats

OSFP224 is not an entirely independent new package specification. Its mechanical dimensions and cage footprint are fully compatible with standard OSFP; only its internal heat dissipation and circuitry are optimized for 224G SerDes. OSFP-XD is a dedicated new package, and the three differ significantly in physical compatibility and maximum power capacity:

V. Selection and Industry Trends

For short-reach networking within 500 meters inside a data center, OSFP224 + DR4 is preferred for the best cost performance. For cross-building campus deployment within 2 kilometers, OSFP224 + FR4 is chosen to reduce fiber infrastructure investment. High-end high-density core facilities adopt OSFP-XD to reserve long-term power consumption headroom.

With the growing adoption of silicon photonic integration, dual-mode 1.6T modules greatly reduce data center iteration costs. Going forward, OSFP224 will become the standardized mainstream, while OSFP-XD will continue to serve high-end computing scenarios.

VI. Summary

1.6T optical modules are the core network infrastructure of the AI computing era. DR4 and FR4 cover mainstream short-reach and medium-reach transmission scenarios respectively; standard OSFP, OSFP224, and OSFP-XD cater to three deployment needs: legacy upgrade, general commercial use, and high-end high-density deployment. A proper combination of optical path and package can balance current service capacity and future bandwidth expansion, making it the optimal standardized interconnection solution for next-generation data centers.

FAQ1: How to choose between 1.6T 2×DR4 and 2×FR4, and what are their scenario differences?

Answer: ① For cabinet interconnection and Spine-Leaf networking with transmission distance ≤500m and sufficient fiber resources, 2×DR4 is preferred for lower overall hardware and cabling costs. ② For cross-building campus links and data center DCI interconnection with distance ≤2km, tight fiber resources, and existing LC cabling, 2×FR4 is the suitable choice.

FAQ2: Can existing 800G OSFP switch cages directly support 1.6T OSFP/OSFP224 modules?

Answer: Physically, they can be plugged in directly — OSFP224 shares identical dimensions with traditional OSFP cages and is fully mechanically compatible. However, the switch ASIC must support 212.5G SerDes electrical signals. Older 800G switches that only support 112G SerDes cannot operate at 1.6T rate. OSFP-XD uses a dedicated cage and cannot be mixed with standard OSFP.

FAQ3: 1.6T modules support 800G/1.6T dual mode. How is the rate switched?

Answer: No hardware replacement is required. Switching is achieved via switch port configuration and the module's built-in DSP:

• When the port is set to 800G mode, the module operates as two independent 800G optical paths.
• When set to 1.6T mode, all 8 optical channels combine to deliver full 1.6T bandwidth. This enables phased, smooth capacity expansion for data centers.

FAQ4: Which switch types match standard OSFP, OSFP224, and OSFP-XD in terms of power and cooling?

Answer:

1. Standard OSFP: 20–26W power consumption, compatible with legacy air-cooled switches, suitable for small-batch low-cost upgrades.
2. OSFP224: Optimized heat dissipation, typical 16–18W power consumption, compatible with mainstream AI air-cooled switches; universal for all DR4/FR4 scenarios with the best commercial cost performance.
3. OSFP-XD: Over 25W cooling capacity, compatible with high-density liquid-cooled switches and future coherent long-reach backbones; mostly deployed in high-end core computing facilities.