Cisco SFP-25G-SR-S
25GBASE-SR SFP Module, Original Cisco
Product Highlights
As data centers scale to meet the demands of virtualization, cloud workloads, and east-west traffic growth, the jump from 10G to 25G at the server-access layer is one of the most impactful upgrades you can make. The Cisco SFP-25G-SR-S is a 25GBASE-SR SFP28 transceiver module that delivers 25 Gbps Ethernet connectivity over multimode fiber, providing a 2.5× bandwidth increase while leveraging your existing MMF cabling plant.
Operating at 850nm with a VCSEL transmitter and LC duplex connector, this module supports link lengths of up to 70m over OM3 and 100m over OM4 multimode fiber — ideal reach for top-of-rack (ToR) and end-of-row (EoR) architectures. The SFP28 form factor is hot-swappable and backward-compatible with SFP+ port cages, simplifying migration paths. Built-in Digital Optical Monitoring (DOM) gives network engineers real-time insight into optical power levels, temperature, and bias current for proactive link health management.
Designed for Cisco Catalyst and Nexus switching platforms with SFP28 ports, the SFP-25G-SR-S requires RS-FEC on the host port for optimal performance. With low power consumption and standards-based IEEE 802.3by compliance, this original Cisco transceiver is a reliable, high-density building block for modern 25G Ethernet fabrics.
Features & Benefits
25 Gbps Short-Reach Performance
The SFP-25G-SR-S delivers 25GBASE-SR connectivity at 850nm over multimode fiber, supporting distances of up to 70m on OM3 and 100m on OM4 cabling. This makes it the go-to optic for short-range, high-bandwidth server-to-switch and switch-to-switch links inside the data center.
Hot-Swappable SFP28 Form Factor
Built on the industry-standard SFP28 form factor with a 20-pin connector, this module supports hot-plug insertion and removal without disrupting adjacent ports. The compact design maximizes front-panel port density, critical for high-radix leaf switches.
Digital Optical Monitoring (DOM)
Integrated DOM/DDM functionality provides real-time telemetry on optical output power, received power, module temperature, laser bias current, and supply voltage. This data enables proactive fault detection and simplifies troubleshooting, reducing mean time to repair.
Low Power, High Density
With a maximum power consumption of just 1.2W, the SFP-25G-SR-S keeps thermal overhead low even in fully populated line cards. This efficiency is essential for dense spine-leaf fabrics where every watt and BTU matters at scale.
Standards-Based Interoperability
Compliant with IEEE 802.3by and the SFP28 Multi-Source Agreement (MSA), this transceiver interoperates with other standards-compliant 25GbE interfaces. RS-FEC is required on the host port to ensure reliable, error-free transmission at full reach.
Deployment Scenarios
Data Center Top-of-Rack (ToR) Connectivity
Connect 25GbE server NICs to leaf switches in a ToR architecture. The SFP-25G-SR-S provides the bandwidth headroom needed for virtualized workloads, storage traffic, and east-west communication — all within the typical sub-100m cable runs of a data center row.
Spine-Leaf Fabric Interconnects
Use 25G SR optics for switch-to-switch uplinks in a spine-leaf topology where inter-switch distances are short. The low power draw and high port density of SFP28 modules allow you to build scalable, non-blocking fabrics cost-effectively.
10G-to-25G Migration
Upgrade existing 10G multimode links to 25G without replacing your OM3/OM4 fiber plant. The SFP28 form factor fits into SFP28-capable ports on newer Cisco Catalyst and Nexus platforms, delivering a 2.5× throughput increase with minimal infrastructure change.
High-Performance Computing (HPC) Clusters
Interconnect compute nodes in HPC environments where low latency and high bandwidth are critical. The 25G SR link provides a cost-effective, standards-based alternative to proprietary interconnects for cluster networking.
General
Optical
Performance
Electrical / Power
Environmental
Compliance
Compatibility Notes
Platform Compatibility: The SFP-25G-SR-S is supported on Cisco platforms with SFP28 ports, including Catalyst 9200 (25G network module), Catalyst 9500, Catalyst 9600, Nexus 9200, Nexus 9300, Nexus 9500, and Nexus 3000 series switches. Always verify your specific platform and software version using the Cisco Transceiver Module Group (TMG) Compatibility Matrix.
FEC Requirement: This module requires RS-FEC (Reed-Solomon Forward Error Correction) to be enabled on the host port for proper operation.
Fiber & Connector: Use OM3 (2000 MHz·km) or OM4/OM5 (4700 MHz·km) multimode fiber with LC/PC or LC/UPC patch cords. APC connectors are not supported.
Operating Temperature: 0°C to 70°C (commercial temperature range).
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| SFP-10/25G-CSR-S | Cisco 10/25GBASE-CSR SFP28 Module | Extended reach — up to 300/400m on OM3/OM4 at 25G; dual-rate 10G/25G support for flexible migration |
| SFP-10/25G-LR-S | Cisco 10/25GBASE-LR SFP28 Module | Single-mode fiber, up to 10 km reach — ideal for campus or inter-building links vs. SR's short-range MMF focus |
| SFP-25G-AOC10M | Cisco 25G SFP28 Active Optical Cable (10m) | Pre-terminated AOC for ultra-short intra-rack connections — lower cost but fixed length, no field-terminable fiber |
| SFP-H25G-CU3M | Cisco 25G SFP28 DAC Cable (3m) | Passive copper direct-attach cable — lowest cost and latency for sub-3m connections, but limited to very short runs |
