Cisco QSFP-40G-SR4
40GBASE-SR4 QSFP Transceiver Module with MPO Connector, Original Cisco
Product Highlights
As data centers and enterprise networks scale to meet growing bandwidth demands, reliable 40 Gigabit Ethernet connectivity becomes essential. The Cisco QSFP-40G-SR4 is an original Cisco 40GBASE-SR4 QSFP+ transceiver module designed to deliver high-bandwidth 40G optical links over multimode fiber using an MPO connector.
The QSFP-40G-SR4 supports link lengths of 100 meters on OM3 and 150 meters on OM4/OM5 laser-optimized multimode fiber, making it an excellent fit for intra-building and intra-data-center connections. It uses four parallel 10 Gbps channels at an 850nm wavelength to achieve an aggregate 40 Gbps throughput. Beyond native 40G operation, this module also supports 4x10G breakout mode, enabling interoperability with 10GBASE-SR and SFP-10/25G-CSR-S (in 10G mode) interfaces via an external MPO-to-LC breakout cable — a key advantage for phased network migrations.
Compliant with IEEE 802.3ba and the QSFP+ MSA, the QSFP-40G-SR4 is hot-swappable and includes digital diagnostics monitoring (DDM) for real-time visibility into operating parameters. Whether you're building out a new 40GbE spine-leaf fabric, connecting top-of-rack switches, or bridging 10G access layers to a 40G aggregation tier, this original Cisco transceiver delivers the performance and compatibility your infrastructure demands.
Features & Benefits
40 Gbps Parallel Optics
The QSFP-40G-SR4 transmits data across four independent 10 Gbps lanes using 850nm VCSEL technology, delivering a full 40 Gbps of aggregate bandwidth. This parallel architecture provides efficient, high-throughput connectivity for bandwidth-intensive workloads without requiring complex wavelength-division multiplexing.
Flexible 4x10G Breakout Mode
Unlike the QSFP-40G-SR4-S, this module supports 4x10G breakout connectivity using an external 12-fiber parallel to 2-fiber duplex breakout cable. This allows a single 40G QSFP+ port to connect to four separate 10GBASE-SR interfaces — ideal for phased migrations from 10G to 40G or for maximizing port utilization on 40G-capable switches.
Short-Range Multimode Fiber Reach
Optimized for short-range deployments, the QSFP-40G-SR4 supports 100m on OM3 and 150m on OM4/OM5 multimode fiber. This covers the vast majority of intra-data-center and campus backbone distances, leveraging existing MMF infrastructure to minimize cabling costs.
Hot-Swappable with Digital Diagnostics
The module is fully hot-swappable, allowing field replacement without powering down the host device. Built-in DDM/DOM provides real-time monitoring of key parameters such as temperature, supply voltage, laser bias current, and transmit/receive optical power via the I2C interface — enabling proactive troubleshooting and reducing mean time to repair.
IEEE & MSA Standards Compliance
Fully compliant with IEEE 802.3ba 40GBASE-SR4 and the QSFP+ Multi-Source Agreement (MSA), the QSFP-40G-SR4 guarantees interoperability with any standards-compliant 40GBASE-SR4 interface. As an original Cisco optic, it is recognized natively on supported Cisco platforms without requiring any unsupported-transceiver commands.
Deployment Scenarios
Data Center Spine-Leaf Fabric
Deploy the QSFP-40G-SR4 in 40GbE spine-to-leaf links within a data center fabric. The 150m reach on OM4 fiber covers typical row-to-row distances, while the high-density QSFP+ form factor maximizes port count per rack unit.
10G to 40G Network Migration
Leverage the 4x10G breakout capability to connect a single 40G uplink port to four 10GBASE-SR access switches. This allows incremental migration from 10G to 40G without forklift upgrades, protecting your existing SFP+ investment.
Enterprise Campus Backbone
Use the QSFP-40G-SR4 to interconnect core and distribution layer switches across campus buildings. The 100–150m multimode reach is well-suited for building-to-building links within a campus environment where existing OM3/OM4 fiber is already deployed.
High-Performance Computing (HPC) Clusters
Connect compute nodes and storage arrays in HPC environments where low-latency, high-bandwidth 40G links are critical. The parallel optics design and hot-swap capability ensure minimal disruption during maintenance windows.
General
Performance
Physical
Power & Environmental
Compliance
Compatibility Notes
The Cisco QSFP-40G-SR4 is supported on a wide range of Cisco platforms. Refer to the Cisco 40 Gigabit Ethernet Transceiver Modules Compatibility Matrix for the definitive list of supported hardware and minimum software versions. Common compatible platform families include:
- Cisco Nexus series (various models with QSFP+ ports)
- Cisco Catalyst series (various models with QSFP+ uplink modules)
- Cisco ASR 9000 series
Cabling: Requires 12-fiber MPO/MTP terminated multimode fiber (OM3 or OM4/OM5). For 4x10G breakout mode, an external 12-fiber MPO to 4x duplex LC breakout cable is required.
Always verify compatibility with the official Cisco compatibility matrix for your specific platform and IOS/NX-OS version.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| QSFP-40G-SR4-S | Cisco 40GBASE-SR4-S QSFP+ (S-Class) | S-Class variant with same reach (100m OM3 / 150m OM4) but does NOT support 4x10G breakout mode. Choose QSFP-40G-SR4 if breakout is needed. |
| QSFP-40G-CSR4 | Cisco 40GBASE-CSR4 QSFP+ | Extended-reach variant supporting up to 300m on OM3 and 400m on OM4/OM5 with 4x10G breakout. Choose CSR4 for longer multimode runs. |
| QSFP-40G-LR4 | Cisco 40GBASE-LR4 QSFP+ | Long-reach 40G module supporting up to 10 km over single-mode fiber with duplex LC connectors. Choose LR4 for inter-building or metro links. |
| QSFP-40G-SR-BD | Cisco 40G BiDi QSFP+ | Bidirectional 40G transceiver using duplex LC connectors over MMF — reuses existing 10G duplex fiber plant without requiring 12-fiber MPO cabling. |
