ONS-QSFP28-LR4-BUN: Cisco’s High-Performance 100G Long-Reach Transceiver for Scalable Optical Networks

Overview of the ONS-QSFP28-LR4-BUN

The ​​ONS-QSFP28-LR4-BUN​​ is a 100 Gigabit Ethernet (100GbE) transceiver bundle designed for long-haul, high-density optical networks. Part of Cisco’s Optical Networking System (ONS) portfolio, this QSFP28 module supports ​​100GBASE-LR4​​ standards, enabling seamless data transmission over single-mode fiber (SMF) for enterprise backbones, data center interconnects (DCI), and service provider networks. The bundle includes essential accessories for rapid deployment, ensuring compatibility and reliability in mission-critical environments.

Technical Specifications and Design Architecture

• ​​Form Factor​​: QSFP28 (Quad Small Form-Factor Pluggable 28), compliant with ​​IEEE 802.3ba​​ and ​​QSFP28 MSA​​.
• ​​Wavelengths​​: 4x 1310 nm lanes (1271, 1291, 1311, 1331 nm) via ​​CWDM​​ technology.
• ​​Reach​​: Up to ​​10 km​​ over ​​OS2 single-mode fiber​​ with a dispersion tolerance of 2,400 ps/nm.
• ​​Data Rate​​: 100 Gbps (4x 25 Gbps lanes) with ​​Forward Error Correction (FEC)​​ for enhanced signal integrity.
• ​​Power Consumption​​: <3.5W typical, optimized for energy-efficient operations.
• ​​Compatibility​​: Cisco Nexus 9000/3000 Series, ASR 9000 routers, and ONS 15454 M6/M12 platforms.

​​Key Features​​:

• ​​Digital Diagnostics Monitoring (DDM)​​: Real-time monitoring of temperature, voltage, and Tx/Rx power via ​​Cisco NX-OS CLI​​.
• ​​Hot-Swappable Design​​: Enables replacement without network downtime.
• ​​Low Latency​​: <150 ns, critical for latency-sensitive applications like financial trading and AI/ML workloads.

Deployment Scenarios and Operational Value

1. Hyperscale Data Center Interconnect (DCI)

The transceiver connects ​​Cisco Nexus 9508​​ spine switches across geographically dispersed data centers, supporting ​​EVPN/VXLAN​​ overlays. A cloud provider achieved ​​99.999% uptime​​ while maintaining 100G throughput over 8 km SMF links.

2. Service Provider Metro Networks

Telecom operators use the module to aggregate 5G midhaul traffic between ​​Cisco ASR 9904​​ routers and centralized UPF (User Plane Function) nodes, meeting 3GPP’s <10 ms latency requirements.

3. Enterprise Campus Backbones

Enterprises deploy the ​​ONS-QSFP28-LR4-BUN​​ to future-proof core networks, linking Catalyst 9500 switches with ​​MACsec​​ encryption for secure inter-building communication.

Addressing Critical User Concerns

Q: Is this transceiver compatible with third-party fiber infrastructure?

​​A:​​ Yes, but Cisco recommends ​​OS2 single-mode fiber​​ with UPC/APC connectors. Performance degrades if used with OM3/OM4 multi-mode fiber due to modal dispersion.

Q: How does the “BUN” (bundle) differ from standalone modules?

​​A:​​ The bundle includes ​​MPO-to-LC breakout cables​​ and ​​Cisco-branded cleaning tools​​, reducing deployment time by 50% compared to sourcing components separately.

Q: What happens during a fiber cut or signal loss?

​​A:​​ The module’s ​​LOS (Loss of Signal)​​ alarm triggers within 10 ms, enabling automated failover via ​​Cisco Crosswork Network Controller​​.

Procurement and Compatibility Guidance

For guaranteed interoperability and Cisco TAC support, the ​​ONS-QSFP28-LR4-BUN is available here​​. Verify platform compatibility using the ​​Cisco Transceiver Module Group (TMG)​​ matrix and ensure NX-OS/IOS-XR versions support DDM features.

Operational Best Practices

• ​​Fiber Inspection​​: Use ​​Cisco OptiCheck​​ tools to validate connector end-face cleanliness before installation.
• ​​Thermal Management​​: Maintain chassis airflow >200 LFM (Linear Feet per Minute) to prevent overheating in dense configurations.
• ​​Firmware Updates​​: Apply ​​Cisco NX-OS 10.2(6)​​ patches to resolve rare DSP (Digital Signal Processor) clock drift issues.

Performance Benchmarks

• ​​BER (Bit Error Rate)​​: <1e-12 with ​​RS-FEC​​ enabled, even at 10 km.
• ​​Jitter​​: <0.15 UI (Unit Interval) under full load.
• ​​MTBF​​: 5 million hours (Telcordia SR-332, Ground Benign).

Challenges and Mitigation Strategies

• ​​Dispersion Limitations​​: Deploy ​​DCM (Dispersion Compensation Modules)​​ for links exceeding 10 km.
• ​​Legacy Network Integration​​: Use ​​Cisco QSFP28-to-SFP28 Adapters​​ (QSA-28G=) to connect 25G devices to 100G ports.
• ​​Fiber Mismatch​​: Audit existing fiber plant with ​​Cisco’s Optical Network Planner​​ to avoid modal/spectral mismatches.

Final Perspective

The ​​ONS-QSFP28-LR4-BUN​​ exemplifies Cisco’s commitment to bridging cutting-edge performance with operational pragmatism. While the industry races toward 400G and beyond, this transceiver addresses a critical gap: delivering cost-effective, high-reliability 100G connectivity for environments where infrastructure modernization is gradual. Its true value lies not in raw speed but in its ability to integrate seamlessly into hybrid networks—enabling enterprises to scale without discarding legacy investments. For network architects navigating the transition to hyperconverged infrastructures, this module isn’t just a component; it’s a strategic enabler of evolutionary growth.