Transceiver Module Cisco QSFP-40G-CSR-S Fiber optic

The QSFP-40G-CSR-S is a pluggable 40G fiber optic transceiver module with a QSFP form factor and duplex LC connector interface for use over multimode fiber (MMF). It supports 40GBASE-CSR operation by running four 10 Gbit/s lanes on four wavelengths over existing duplex OM3 or OM4 MMF, enabling reuse of 10 Gigabit duplex MMF infrastructure while keeping the same supported link distances.

Advantages

This Cisco QSFP-40G-CSR-S transceiver supports 40 Gbit/s aggregation using four 10G lanes, works with laser-optimized OM3 and OM4 multimode fibers, and provides link reach of up to 300 m on OM3 and 400 m on OM4. It uses standard LC duplex connectors for straightforward integration into existing duplex MMF cabling and offers a QSFP interface for compatibility with QSFP ports on switches and routers. The module does not support FCoE.

Suitable for

• Data center uplinks and aggregation where 40 Gigabit Ethernet is required over MMF
• Migration from 10G to 40G while reusing existing duplex OM3/OM4 cabling
• High-density switch-to-switch links using QSFP ports and LC duplex connectors

Key specifications

• Standard: 40GBASE-CSR
• Data rate: 40 Gbit/s (4 × 10 Gbit/s lanes)
• Connector: Duplex LC
• Fiber type: Multimode (OM3 / OM4)
• Typical reach: 300 m on OM3, 400 m on OM4
• Form factor: QSFP
• FCoE support: Not supported

How to use

Insert the QSFP-40G-CSR-S module into a compatible QSFP port on your switch or router, and connect the duplex LC patch cables to the multimode fiber links. Ensure the switch or host transceiver port is configured for 40G operation and that the connected fiber is OM3 or OM4 rated for the required distance. Verify link status and speed through the device management interface.

Recommendations

Use laser-optimized OM3 or OM4 duplex multimode fiber and high-quality LC patch cords. Confirm QSFP port compatibility with Cisco devices and check firmware or driver requirements. Do not use this module for FCoE traffic as it is not supported.