What is 40G QSFP+ Transceiver?
40G QSFP+ transceiver refers to the Quad-Small-Form-Factor-Pluggable Plus Module. It is a hot-swappable, parallel fiber-optic module with 4 independent 10G data tracks in each direction for a total speed of 40 Gbps. QSFP+ transceiver also called a QSFP+ module, and it is fully compliant with the QSFP+ MSA standard. According to the QSFP standard, the 40G QSFP + terminal can be either a duplex LC or 12 fiber MTP / MPO port. 40G QSFP+ modules provide customers with a wide range of high-density 40 Gigabit Ethernet connectivity options for data centers, high-performance computing networks, enterprise core, and distribution layers, and transport applications for service providers.
QSFP-40G-SR4 40GBASE-SR4 Transceiver
Cisco QSFP-40G-SR4 is a 40GBASE-SR4 QSFP+ transceiver. It fully complies with the 40GBASE-SR4 standard. The QSFP-40G-SR4 supports link lengths of 100m and 150m on laser-optimized OM3 and OM4 multimode fibers. Cisco QSFP-40G-SR4 enables high-bandwidth 40G optical links mainly through ribbon fiber optic cables terminated with fiber optic connectors, and can also be used along with ribbon fiber to breakout cables for connection to four 10GBASE-SR optical interfaces.
QSFP-40G-SR4-S 40GBASE-SR4 Transceiver
QSFP-40G-SR4-S is typically standing for Cisco S-Class 40GBASE-SR4 QSFP module. It supports link lengths of 100 and 150 meters, respectively, on laser-optimized OM3 and OM4 multimode fibers. It primarily enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber connectors. The QSFP-40G-SR4-S is optimized to guarantee interoperability with any IEEE-compliant 40GBase-SR4 QSFP module.
QSFP-40G-SR-BD 40GBASE-SR BiDi Transceiver
QSFP-40G-CSR4 40GBASE-SR BiDi Transceiver
QSFP-40G-SR4 vs QSFP-40G-SR4-S vs QSFP-40G-SR-BD vs QSFP-40G-CSR4 Comparison, What is the difference?
The comparison between QSFP-40G-SR4 vs QSFP-40G-SR4-S vs QSFP-40G-SR-BD vs QSFP-40G-CSR4 is shared as below.
| Features | QSFP-40G-SR4 | QSFP-40G-SR4-S | QSFP-40G-SR-BD | QSFP-40G-CSR4 |
| Appearance | ||||
| Transceiver Type | QSFP+ Module | QSFP+ Module | QSFP+ Module | QSFP+ Module |
| Wavelength | 850 nm | 850 nm | 832~918 nm | 850 nm |
| Reach | 100m@OM3, 150m@OM4 | 100m@OM3, 150m@OM4 | 100m@OM3, 150m@OM4 | 300m@OM3, 400m@OM4 |
| Fibre Type | Multimode Fiber (MMF) | Multimode Fiber (MMF) | Multimode Fiber (MMF) | Multimode Fiber (MMF) |
| Connector Type | MPO | MPO | LC Duplex | MPO |
| Data Rate | 40 Gbps | 40 Gbps | 40 Gbps | 40 Gbps |
| Cabling Type | Ethernet 40GBASE-SR4 Cabling | Ethernet 40GBASE-SR4 Cabling | Ethernet 40GBASE-SR BiDi Cabling | Ethernet 40GBASE-CSR4 Cabling |
| DOM Support | Yes | Yes | Yes | Yes |
| Operating Temperature | 0°C to 70°C (Commercial Grade) | 0°C to 70°C (Commercial Grade) | 0°C to 70°C (Commercial Grade) | 0°C to 70°C (Commercial Grade) |
| Storage Temperature | -40°C to 85°C | -40°C to 85°C | -40°C to 85°C | -40°C to 85°C |
| Weight | 0.05 kg | 0.05 kg | 0.05 kg | 0.05 kg |
| Other features | Non-S-Class | S-Class | Non-S-Class | Non-S-Class |
Conclusion
As the above comparison, you may choose the right QSFP+ module for your network. If your link distance is less than 150 meters, then QSFP-40G-SR4 or QSFP-40G-SR4-S transceiver is the right one. If your link distance is more than 150 meters, then QSFP-40G-CSR4 transceiver is the better one. If you need to transmit on duplex multimode fiber, then QSFP-40G-SR-BD will be the best choice, because it allows you to reach bidirectional connectivity over OM3 or OM4 multimode fiber.