Cisco SFP-10/25G-LR-I=: Dual-Rate Optical Transceiver for Hybrid 10G/25G Network Environments

Technical Architecture & Design Philosophy

The ​​Cisco SFP-10/25G-LR-I=​​ represents a breakthrough in multi-rate optical connectivity, combining ​​10GBASE-LR​​ and ​​25GBASE-LR​​ capabilities within a single SFP28 form factor. This dual-mode transceiver operates at ​​1310nm wavelength​​ over single-mode fiber (SMF), achieving ​​10km reach​​ for both speed profiles through adaptive DSP optimization. Key innovations include:

• ​​FlexRate Technology​​: Dynamically adjusts PAM4/NRZ modulation based on detected link speed (10.3125Gbps or 25.78125Gbps) without manual reconfiguration.
• ​​Industrial-Grade Resilience​​: Functions at ​​-40°C to +85°C​​ ambient temperatures, making it suitable for 5G fronthaul deployments and outdoor cabinets.
• ​​Power-Efficient Design​​: Consumes 1.8W at 10G mode and 2.4W at 25G mode – 35% lower than separate 10G/25G modules.

Compatibility & Performance Benchmarks

​​Supported Platforms​​

• ​​Catalyst 9000 Series​​: Requires IOS-XE 17.9+ with Enhanced QSA Adapter (CVR-QSFP-SFP10G) for 25G operation
• ​​Nexus 9300-FX2/FX3 Switches​​: Native support via 25G-capable ports (speed auto-negotiation enabled)

​​Interoperability Testing​​

In 2024 validation with mixed-speed networks:

• ​​Latency​​: 320ns at 10G, 280ns at 25G (FEC disabled)
• ​​Error Rate​​: BER <1E-15 across 72-hour stress tests

Addressing Critical Deployment Questions

“How to Enable Speed Auto-Negotiation in Legacy Switches?”

For Cisco 3850/3650 series:

interface GigabitEthernet1/1/1  
speed auto 10000 25000  

​​Note​​: Requires Advanced IP Services license and QSFP28 uplink modules.

“Can It Backward-Compatible with 1G SFP Ports?”

No – the module requires ​​minimum 10G electrical interface​​. For 1G/10G/25G flexibility, consider Cisco QSFP-100G-SR4-S with breakout cables.

“What Fiber Specifications Ensure 25G Performance?”

• ​​Dispersion Compensation​​: ≤18ps/nm for OM4 MMF (300m)
• ​​Connector Polish​​: UPC (Ultra Physical Contact) with ≤0.2dB insertion loss
• ​​Cleaning Interval​​: Every 6 months using CISCO-CLEAN-KIT2

Optimization Strategies for Hybrid Networks

​​5G Fronthaul Aggregation​​

Deploy in Cisco ASR 9000 routers to handle ​​CPRI/eCPRI​​ traffic from 32-64 cell sites. Key configuration:

controller CPRI 0/0/0  
cpri rate 9.8G  
loopback internal  

​​Data Center Spine-Leaf Migration​​

Use speed-shifting capabilities during 10G→25G fabric upgrades:

1. Phase 1: 25G spine ↔ 10G leaf (existing Cat9K)
2. Phase 2: Full 25G mesh after leaf refresh

Reduces CapEx by 40% compared to parallel networks.

Procurement & Lifecycle Management

For guaranteed interoperability with Cisco DNA Center assurance features, the SFP-10/25G-LR-I= is available here with optional 5-year advanced replacement.

Operational Realities

The SFP-10/25G-LR-I= fills a critical gap in network evolution strategies. While 100G/400G solutions dominate headlines, many enterprises remain trapped in “speed limbo” – needing to support legacy 10G applications while testing 25G workloads. This module’s true value emerges in financial trading networks where low-latency 25G links handle algorithmic traffic while maintaining 10G backup paths. However, organizations must audit existing fiber plants – older OS1 cables may struggle with 25G’s tighter polarization mode dispersion tolerances. As a transitional solution, it buys time for structured migration to 400G-ZR coherent optics without stranded assets.