Cisco QSFP-40G-SR4-S
40GBASE-SR4 QSFP Trnscvr Module, MPO Conn, Enterprise-Class, Original Cisco
Product Highlights
As data center and campus networks scale to meet ever-growing bandwidth demands, reliable 40 Gigabit Ethernet connectivity becomes a non-negotiable requirement. The Cisco QSFP-40G-SR4-S is an enterprise-class (S-Class) 40GBASE-SR4 QSFP+ transceiver module purpose-built for high-bandwidth optical links over multimode fiber.
The QSFP-40G-SR4-S utilizes four independent 10 Gbps transmit and receive channels operating at 850nm via VCSEL laser technology, delivering an aggregate throughput of 40 Gbps. Connected through an MPO/MTP 12-fiber parallel interface, it supports link lengths of up to 100 meters on OM3 multimode fiber and up to 150 meters on OM4/OM5 multimode fiber — covering the vast majority of intra-building and intra-campus fiber runs.
Aligned to IEEE 802.3ba 40GBASE-SR4 optical specifications and fully compliant with the QSFP+ Multi-Source Agreement (SFF-8436), this original Cisco transceiver is optimized for interoperability with any IEEE-compliant 40GBASE-SR4 module. Built-in Digital Diagnostics Monitoring (DDM) provides real-time insight into key operating parameters, while the hot-swappable form factor enables seamless maintenance. With power consumption under 1.5W and a commercial operating temperature range of 0°C to 70°C, the QSFP-40G-SR4-S is an efficient, dependable choice for enterprise and data center 40GbE deployments.
Features & Benefits
Enterprise-Class 40GbE Performance
The QSFP-40G-SR4-S delivers 40 Gbps of aggregate bandwidth across four parallel 10 Gbps optical lanes. This parallel architecture provides the throughput needed for spine-leaf data center fabrics, high-performance computing clusters, and bandwidth-intensive enterprise uplinks — all through a single compact QSFP+ module.
Optimized Short-Range Multimode Fiber Reach
Operating at 850nm with VCSEL laser technology, this transceiver supports link lengths of 100m on OM3 and 150m on OM4/OM5 laser-optimized multimode fiber. This reach comfortably covers typical data center row-to-row, floor-to-floor, and intra-campus connections — eliminating the cost premium of single-mode optics where they aren't needed.
Digital Diagnostics Monitoring (DDM/DOM)
Built-in DDM functionality enables real-time monitoring of critical transceiver parameters such as optical transmit and receive power, temperature, supply voltage, and laser bias current. This proactive visibility helps network teams identify degrading links before they cause outages, reducing mean time to repair and improving overall network reliability.
Hot-Swappable & Low Power Design
The QSFP-40G-SR4-S is electrically hot-swappable, allowing field replacement without shutting down the host switch or router. Combined with power consumption under 1.5W per module, it minimizes both operational disruption and energy costs — a meaningful advantage in high-density deployments with dozens or hundreds of 40G ports.
Standards-Based Interoperability
Fully compliant with IEEE 802.3ba 40GBASE-SR4 and the QSFP+ MSA (SFF-8436), the QSFP-40G-SR4-S is optimized to interoperate with any IEEE-compliant 40GBASE-SR4 module on the other end of the link. This standards alignment protects your investment and simplifies multi-vendor network environments.
Deployment Scenarios
Data Center Spine-Leaf Fabric Interconnects
Deploy the QSFP-40G-SR4-S in spine-to-leaf switch uplinks within your data center fabric. The 40 Gbps throughput and short-range multimode reach are ideal for the high-bandwidth, low-latency east-west traffic patterns that define modern data center architectures.
Enterprise Campus Core-to-Distribution Uplinks
Use the QSFP-40G-SR4-S to connect campus core switches to distribution-layer aggregation switches over existing OM3/OM4 multimode fiber plant. The 100–150m reach covers most riser and intra-building runs, delivering a cost-effective 40GbE upgrade path.
High-Performance Computing (HPC) Cluster Interconnects
Connect compute nodes, storage arrays, and top-of-rack switches in HPC environments where low-latency, high-bandwidth 40GbE links are essential. The low power consumption and hot-swap capability simplify operations in dense rack configurations.
General
Optical
Performance
Electrical
Physical
Environmental
Compliance
Compatibility Notes
The QSFP-40G-SR4-S is an S-Class (enterprise-class) Cisco transceiver supported across a range of Cisco switching and routing platforms with QSFP+ ports. For the definitive list of supported hardware and minimum software versions, refer to the Cisco 40 Gigabit Ethernet Transceiver Modules Compatibility Matrix on Cisco.com.
Important considerations:
- The QSFP-40G-SR4-S does not support 4x10G breakout connectivity. If you require breakout to four 10GBASE-SR links, use the QSFP-40G-SR4 or QSFP-40G-CSR4 instead.
- The QSFP-40G-SR4-S does not support FCoE.
- Requires 12-fiber MPO/MTP terminated multimode fiber (OM3, OM4, or OM5).
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| QSFP-40G-SR4 | Cisco 40GBASE-SR4 QSFP+ (Non-S-Class) | Supports 4x10G breakout mode to 10GBASE-SR interfaces; broader feature set but different platform support tier than the S-Class. |
| QSFP-40G-CSR4 | Cisco 40GBASE-CSR4 QSFP+ | Extended-reach variant supporting up to 300m on OM3 and 400m on OM4; also supports 4x10G breakout to 10GBASE-SR. |
| QSFP-40G-LR4-S | Cisco 40GBASE-LR4-S QSFP+ (S-Class) | Long-reach 40G transceiver using single-mode fiber with LC duplex connector; supports up to 10 km — ideal when MMF reach is insufficient. |
| QSFP-40G-SR-BD | Cisco 40GBASE-SR BiDi QSFP+ | Bidirectional 40G transceiver using LC duplex over MMF (2-fiber); enables 40G over existing 10G duplex fiber plant without re-cabling to MPO. |
