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The main differences between 25G CSR (usually referring to Cisco’s SFP-10/25G-SR-S) and 25G SR (SFP-25G-SR-S) SFP modules are transmission distance, speed flexibility, and application scenarios. CSR is an enhanced version of SR, particularly suitable for long-distance multi-mode scenarios that require smooth transitions between 10G and 25G.
Here is a detailed comparison between the 10 25Gbase CSR and SR SFP module:
Transmission Distance
- 25G SR (Short Range): A SFP28 standard short distance optical module. When using OM4 multimode fiber, the maximum transmission distance is 100 meters.
- 25G CSR (Combo/Campus Short Range): “Campus” Short Range, representing a longer distance. On OM4 fiber, it can support a transmission distance of up to 300-400 meters, significantly longer than SR.
Rate Flexibility
- 25G SR: Typically designed to operate only at 25Gbps rates (or compatible fixed low rates).
- 25G CSR: It is a dual rate 10 25Gbase CSR SFP module. It can run at two speeds: 10Gbps and 25Gbps.
Application Scenarios
- 25G SR: Designed specifically for high-speed and short distance connections between servers and switches in data centers, pursuing low power consumption and low cost.
- 25G CSR: mainly used for upgrading enterprise park networks. It allows users to upgrade core switches to 25G while access layer switches remain at 10G, achieving smooth migration from 10G to 25G and protecting investments.
Comparison of Key Technical Parameters
| Item | 25G SR (SFP-25G-SR-S) | 25G CSR (SFP-10/25G-CSR-S) |
| wavelength | 850nm | 850nm |
| fiber type | MMF) | MMF |
| Distance (OM4) | 100 meter | ~400 meter |
| Distance (OM3) | 70 meter | ~300 meter |
| rate | 25G | 10G / 25G dual rate |
| Main applications | Inside the data center rack | Core/Aggregation Layer of Enterprise Park Network |
Conclusion
- If you need high-density, extremely short distance (<100 meters) 25G interconnection within a data center, choose SR transceiver.
- If you are upgrading your campus network and require longer transmission distances (<300 meters/400 meters) or compatibility with 10G old equipment, choose CSR transceiver.
