Cisco QSFP-40G-ER4
QSFP 40GBASE-ER4 Transceiver Module, LC, 40KM, Original Cisco
Product Highlights
When your network demands high-bandwidth connectivity across campus buildings, metro rings, or data center interconnects spanning tens of kilometers, short-reach optics simply won't cut it. The Cisco QSFP-40G-ER4 is an original Cisco 40GBASE-ER4 QSFP+ transceiver module purpose-built for extended-reach 40 Gigabit Ethernet deployments over single-mode fiber.
The module supports link lengths of up to 40 km over G.652 single-mode fiber using a standard duplex LC connector. Internally, it multiplexes four independent 10 Gbps channels across four CWDM wavelengths in the 1310 nm range, delivering an aggregate 40 Gbps of throughput on just two fibers. Multiplexing and demultiplexing are handled entirely within the device, so no external WDM equipment is required.
Compliant with IEEE 802.3ba 40GBASE-ER4 and OTU3 specifications, the QSFP-40G-ER4 fits both enterprise Ethernet and telecom OTN use cases. Built-in digital diagnostics monitoring (DOM) provides real-time insight into key operating parameters such as optical TX/RX power, temperature, and supply voltage — giving network teams the visibility they need to proactively manage link health. As a hot-swappable QSFP+ module, it can be inserted or removed without disrupting the host platform, minimizing maintenance windows and operational risk.
Features & Benefits
Extended-Reach 40G Connectivity
The QSFP-40G-ER4 supports link distances of up to 40 km over standard G.652 single-mode fiber, making it ideal for metro, campus backbone, and data center interconnect scenarios where short-reach optics fall short. By eliminating the need for intermediate signal regeneration, it reduces both equipment costs and points of failure in long-haul 40G links.
4-Channel CWDM Multiplexing
The module carries the 40GE or OTU3 signal over four CWDM wavelengths in the 1310 nm range, with all multiplexing and demultiplexing managed within the device. This allows 40 Gbps aggregate throughput over a simple two-fiber duplex LC connection — no external mux/demux hardware required, keeping your fiber plant lean and cost-effective.
Hot-Swappable QSFP+ Design
The standard QSFP+ form factor enables hot-swap installation and removal without powering down the host switch or router. This means faster deployments, zero-downtime maintenance, and the flexibility to upgrade or troubleshoot optics during production hours.
Digital Diagnostics Monitoring (DOM)
Built-in DOM capabilities provide real-time monitoring of critical parameters including optical transmit and receive power, module temperature, supply voltage, and laser bias current. This data is accessible via the I2C interface per the QSFP+ MSA, enabling proactive fault detection and simplified troubleshooting.
Dual-Standard Compliance
The QSFP-40G-ER4 is compliant with both IEEE 802.3ba 40GBASE-ER4 and OTU3 standards, making it versatile enough for enterprise Ethernet switching as well as telecom OTN client-side transport. This dual-standard support protects your investment across evolving network architectures.
Deployment Scenarios
Data Center Interconnect (DCI)
Connect geographically separated data centers with 40 Gbps links over distances up to 40 km on single-mode fiber. The QSFP-40G-ER4 eliminates the need for intermediate amplification or regeneration, reducing latency and infrastructure complexity for DCI deployments.
Metro / Campus Backbone
Ideal for metropolitan-area networks and large campus backbones where buildings or distribution nodes are separated by several kilometers. The extended 40 km reach on duplex LC fiber provides high-bandwidth aggregation without deploying costly DWDM systems.
Service Provider / Telecom OTN Transport
With OTU3 compliance, the QSFP-40G-ER4 serves as a client-side optic for OTN transport platforms. Service providers can leverage it for 40G client connections feeding into their optical transport network, supporting both Ethernet and OTN encapsulation.
Enterprise Core & Distribution Layer
Deploy in the enterprise core or distribution layer to provide high-speed 40G uplinks between aggregation switches and core routers. The extended reach ensures connectivity even across sprawling enterprise campuses without requiring fiber amplification.
General
Performance
Optical
Electrical & Power
Environmental
Compliance
Compatibility Notes
The Cisco QSFP-40G-ER4 is an original Cisco transceiver designed for use in Cisco platforms with QSFP+ ports that support 40GBASE-ER4 optics. Compatible platform families include (but may not be limited to):
- Cisco Nexus series (e.g., Nexus 3132Q, 3172PQ, 31108PC-V, 56128P, 6001P, 7000/7700 with appropriate line cards, Nexus 9300 with 40G QSFP+ uplink modules)
- Cisco Catalyst series (e.g., Catalyst 9200 with 40G network module, Catalyst 9300/9300L, Catalyst 9500-24Y4C/48Y4C)
Always verify transceiver support in the Cisco Transceiver Compatibility Matrix for your specific platform and software version. The minimum cabling distance is 2 meters per the IEEE 802.3 standard for ER4 modules. Use G.652 single-mode fiber (OS2) for distances up to 40 km.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| QSFP-40G-LR4 | Cisco 40GBASE-LR4 QSFP+ | Supports up to 10 km on SMF — choose LR4 when shorter reach is sufficient and cost savings are desired. |
| QSFP-40G-SR4 | Cisco 40GBASE-SR4 QSFP+ | Short-reach module for multimode fiber (up to 150 m on OM4) with MPO connector — ideal for intra-data-center links. |
| QSFP-4X10G-LR-S | Cisco 4x10G LR QSFP+ | Supports 4×10G breakout to four 10GBASE-LR SFP+ interfaces over 10 km SMF — choose when 10G fan-out is needed. |
| QSFP-40G-LX4 | Cisco 40GBASE-LX4 QSFP+ | Supports up to 2 km on multimode or single-mode fiber with LC connector — a lower-cost option for short campus links. |
