Cisco 40GBase-CSR4 40Gbps Multi-Mode Fiber Transceiver Module

The Cisco QSFP-40G-CSR4 is a multimode fiber transceiver module that delivers 40 Gigabit Ethernet connectivity inside data centers, campus cores, and high-performance computing clusters. It combines four 10 Gigabit channels into a single 40 Gbps link, giving network engineers a straightforward way to move large volumes of traffic between switches, routers, servers, or storage arrays without replacing existing multimode cabling.

The module supports distances of up to 300 meters on OM3 fiber and 400 meters on OM4 fiber, so it comfortably covers most rack-to-rack or room-to-room runs within modern facilities. Installation is simple: slide the transceiver into any Cisco device with a standard QSFP+ port and connect an MPO or MTP cable. The familiar 12-fiber ribbon interface aligns with common trunk infrastructures, which means you can upgrade bandwidth while keeping cable management intact.

For environments that need flexible port allocations, the transceiver can run in a 4 x 10G breakout mode when used with a ribbon-to-duplex fan-out cable. This capability lets a single QSFP+ port feed up to four independent 10GBase-SR connections, an approach often used to aggregate server or storage links into a top-of-rack switch.

Low power draw and a space-saving footprint make the Cisco QSFP-40G-CSR4 a practical choice for high-density deployments. Whether you are building a new leaf-spine fabric or extending an existing enterprise backbone, the module provides a reliable, standards-based path to higher throughput without adding operational complexity.

• 40 Gbps total bandwidth carried over four parallel 10 Gbps lanes
• Up to 300 meters reach on OM3 laser optimized multimode fiber
• Up to 400 meters reach on OM4 laser optimized multimode fiber
• MPO or MTP connector for direct termination to 12-fiber ribbon cables
• 4 x 10G breakout mode supports multiple 10GBase-SR interfaces through a fan-out cable
• Compatible with any Cisco platform that offers a QSFP+ slot
• Low power consumption and compact size help maximize port density