As the networking industry embraces 100G and even 400G technologies, it’s natural to question the relevance of legacy solutions like 40G SR (Short Range) optical modules. While hyperscalers and large data centers are racing toward higher bandwidths to support AI workloads and massive data demands, small and medium-sized businesses (SMBs) face a different reality — one that is governed by tighter budgets, simpler topologies, and slower growth rates. So, can 40G SR still play a meaningful role in SMB backbone networks in the age of 100G? The answer is a cautious but confident yes, especially when considering redundancy, cost-efficiency, and deployment practicality.
The Economics of “Good Enough”
SMBs often operate on limited IT budgets, making every network investment a strategic decision. While 100G optics are becoming more accessible, 40G SR modules offer a compelling price-performance ratio for businesses that don’t require the high throughput of newer modules. In many SMB environments, 40G SR is “good enough” to handle the aggregated uplink traffic from multiple access switches or servers without introducing performance bottlenecks. Given that 40G SR modules are mature and widely available on the secondary market, they offer an affordable upgrade path without the need for a significant infrastructure overhaul.
Redundancy Without Overkill
Redundancy is crucial in any business network, but it doesn’t always need to come with the latest and greatest tech. QSFP+ SR transceivers can provide robust, short-reach backbone connections between distribution and core layers or between server racks. As a redundant path — either in active-active or active-standby topologies — 40G links ensure business continuity without inflating power consumption or hardware costs.
For example, SMBs deploying two parallel paths between network nodes — one using 100G as the primary and 40G SR as the backup — gain the benefits of fault tolerance and bandwidth scalability while keeping investment under control.
Compatibility and Simplicity
Another advantage of 40G SR for SMBs is its compatibility with existing multimode OM3 or OM4 fiber cabling. Most SMBs already have a structured cabling system that supports short-range optics. Using QSFP+ 40G SR modules means avoiding the costs and downtime associated with rewiring or upgrading to single-mode infrastructure that 100G modules like CWDM4 or ER4 often require.
Moreover, 40G SR modules are hot-pluggable and relatively easy to deploy. Their use of MTP/MPO connectors for 8-fiber transmission (4 Tx and 4 Rx) simplifies the backbone setup and reduces the learning curve for IT teams that may not have deep fiber optic expertise.
Looking Ahead: A Strategic Transition Tool
While 100G adoption will continue to grow, it doesn’t mean 40G SR is obsolete. For SMBs planning gradual network upgrades, 40G SR can serve as a transitional technology, offering performance that meets current needs while preserving budget for future improvements.
Organizations that don’t yet require the full bandwidth of 100G but want to prepare for future demand can adopt a hybrid approach. This involves integrating 40G SR as a secondary backbone layer or for specific applications like server aggregation or inter-rack connections, while reserving 100G for external uplinks or high-priority traffic.
Conclusion
In the 100G era, 40G SR may not be the fastest horse on the track, but it remains a strategic choice for SMBs seeking reliable, cost-effective, and redundant backbone connectivity. For short-reach deployments, legacy cabling environments, and incremental upgrade paths, 40G SR continues to offer real-world value, making it far from irrelevant in today’s networking landscape.