As 100G and even 400G optical modules become mainstream in hyperscale and carrier-grade environments, it's easy to assume that 40G optics, particularly 40G SR (Short Reach), are obsolete. However, in 2025, many data centers and enterprise networks are still finding strong return on investment (ROI) in deploying 40G SR modules—especially in short-distance backbone links, aggregation layers, and legacy infrastructure upgrades.

Cost-Effective for Short-Distance Links

One of the main strengths of 40G modules lies in their cost efficiency for short-distance connections, typically under 100 meters using OM3 or OM4 multimode fiber. In many medium-sized data centers, server-to-switch or switch-to-core links rarely exceed this distance, making 40G SR a perfect balance between bandwidth and cost. Compared to 100G modules, 40G SR remains more affordable in both module price and required cabling infrastructure, especially when reusing existing MPO-12 patch panels and fiber trunks.

Ideal for Non-Mission-Critical Segments

Not every part of a network needs 100G or higher speeds. For departments or business units that don’t rely on ultra-low latency or maximum throughput, 40G provides sufficient bandwidth at a fraction of the cost. This makes 40G SR ideal for connecting IDFs (Intermediate Distribution Frames), storage systems, or backup clusters in enterprise environments.

Easier Upgrades from 10G Aggregation

40G SR modules can be easily integrated into environments where 10G aggregation switches are being phased out. Using MPO to LC breakout cables, one 40G port can support four 10G links, providing flexibility during the migration phase. For IT teams working with constrained budgets, this staged upgrade approach maximizes infrastructure reuse while incrementally boosting network performance.

Reduced Power Consumption Compared to Higher Speeds

While 100G and 400G optics deliver superior throughput, they typically consume more power and generate more heat. In power-sensitive deployments—such as remote edge sites or compact server rooms—40G SR modules offer a lower-power alternative that supports efficient cooling and hardware longevity.

Conclusion

While the industry is undeniably moving toward 100G and beyond, 40G SR is far from obsolete. When used in the right scenarios—such as short-reach links, non-critical network segments, or gradual upgrade paths—40G SR can still deliver excellent ROI in 2025. For many data center operators and enterprise IT managers, it remains a smart, pragmatic choice.