Cisco QSFP-40G-LR4-S
QSFP 40GBASE-LR4 Trnscvr Mod. LC. 10km. Enterprise-Class, Original Cisco
Product Highlights
Extending 40 Gigabit Ethernet beyond the confines of a single wiring closet or data hall shouldn't mean compromising on reliability or manageability. The Cisco QSFP-40G-LR4-S is an original Cisco enterprise-class QSFP+ transceiver module purpose-built for 40GBASE-LR4 connectivity over distances up to 10 km on standard G.652 single-mode fiber.
The module multiplexes four 10 Gbps electrical channels onto four CWDM wavelengths (1271, 1291, 1311, and 1331 nm) and transmits them through a single duplex LC connector — eliminating the need for parallel fiber or MPO cabling. On the receive side, integrated demultiplexing recovers the four lanes transparently. This makes the QSFP-40G-LR4-S ideal for inter-building links, campus backbone uplinks, and data center spine-to-leaf connections where reach beyond short-range multimode is required.
As an S-Class module, the QSFP-40G-LR4-S supports 40GBASE Ethernet only (it does not support OTU3 or FCoE), keeping it streamlined for enterprise switching environments. It is hot-swappable, supports digital optical monitoring (DOM) for proactive link health management, and is certified and tested on Cisco QSFP 40G ports for guaranteed compatibility. With a maximum power consumption of just 3.5 W and a commercial operating temperature range, it fits seamlessly into dense aggregation and core switch deployments.
Features & Benefits
40GBASE-LR4 Long-Reach Connectivity
The QSFP-40G-LR4-S supports link lengths of up to 10 km over a standard pair of G.652 single-mode fiber with duplex LC connectors. This eliminates the distance limitations of multimode optics and enables campus backbone, inter-building, and metro-edge deployments without signal regeneration.
4-Lane CWDM Wavelength Multiplexing
Four 10 Gbps channels are carried over CWDM wavelengths at 1271, 1291, 1311, and 1331 nm, all multiplexed and demultiplexed within the module. This delivers 40 Gbps aggregate throughput over just two fibers (TX/RX), simplifying cabling infrastructure and reducing fiber strand counts compared to parallel-fiber alternatives.
Enterprise S-Class Simplicity
The S-Class designation means this module is optimized for 40GBASE Ethernet only — it does not carry OTU3 or FCoE traffic. For enterprise switching environments where Ethernet is the sole requirement, this focused design ensures straightforward deployment and Cisco-certified reliability.
Hot-Swappable & DOM-Enabled
The QSFP+ form factor allows tool-free, hot-swappable installation into any compatible Cisco 40G QSFP port. Built-in Digital Optical Monitoring (DOM) provides real-time telemetry — including temperature, supply voltage, laser bias current, and per-lane optical power — enabling proactive fault detection and SNMP-based network management.
Low Power, High Density
With a maximum power draw of just 3.5 W, the QSFP-40G-LR4-S keeps thermal output low even in fully populated line cards. This translates directly to reduced cooling costs and higher port density in space-constrained data center and campus core environments.
Deployment Scenarios
Campus Backbone / Inter-Building Links
Connect campus core switches across buildings up to 10 km apart using existing single-mode fiber plant. The QSFP-40G-LR4-S provides a reliable, high-bandwidth backbone without the cost of deploying new fiber or intermediate repeaters.
Data Center Spine-to-Leaf Uplinks
In larger data center fabrics where spine and leaf switches reside in separate halls or floors, the 10 km reach of the LR4 optic ensures consistent 40G uplink performance over longer single-mode runs that exceed short-range SR4 distances.
Enterprise Core Aggregation
Aggregate traffic from distribution-layer switches into high-performance core routers or switches. The 40 Gbps throughput and long-reach capability make this transceiver well-suited for consolidating multiple 10G uplinks into a single 40G trunk.
Disaster Recovery / Secondary Site Connectivity
Establish dedicated 40G fiber links between primary and DR sites within a metro campus. The 10 km reach covers most intra-campus DR scenarios, supporting high-speed replication and failover traffic.
General
Performance
Physical
Environmental
Compliance
Compatibility Notes
The QSFP-40G-LR4-S is designed for use in Cisco platforms with QSFP+ 40G ports. Compatible platforms include various models across the Nexus 2000, 3000, 5000, 6000, 7000, and 9000 Series switches, as well as Catalyst 3850, 9200, 9300, 9300L, and 9500 Series switches, and ASR 1000 and ASR 9000 Series routers, among others.
Important: Always verify compatibility for your specific platform and software release using the Cisco Transceiver-to-Device Compatibility Matrix before ordering.
The minimum cabling distance for LR4 modules is 2 meters per IEEE 802.3. Use G.652 single-mode fiber with duplex LC patch cords.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| QSFP-40G-LR4 | Cisco 40GBASE-LR4 QSFP (Multi-Rate) | Supports both 40GBASE-LR4 Ethernet and OTU3 data rates; choose this if OTN transport is required. |
| QSFP-40G-SR4-S | Cisco 40GBASE-SR4-S QSFP (Short-Range) | Short-range multimode (OM3/OM4) optic for up to 150 m; lower cost for intra-rack or intra-row links. |
| QSFP-40G-ER4 | Cisco 40GBASE-ER4 QSFP (Extended-Range) | Extends reach to 40 km over SMF for metro or long-haul campus links beyond 10 km. |
| QSFP-4X10G-LR-S | Cisco 4×10G LR QSFP (Breakout-Capable) | Supports 4×10G breakout mode for interoperability with 10GBASE-LR interfaces; uses MPO connector. |
