Cisco ONS-SI-155-SR-MM=: Enterprise-Grade Short-Reach Multimode Optical Transceiver for SONET/SDH Networks

Product Overview and Functional Role

The ​​Cisco ONS-SI-155-SR-MM=​​ is a ​​155 Mbps short-reach multimode optical transceiver​​ designed for Cisco’s ONS 15454 Multiservice Transport Platform (MSTP). It enables cost-effective, low-latency connectivity in enterprise metro access networks, campus backbones, and legacy SONET/SDH environments. Optimized for distances up to 2 km, this module simplifies migration from TDM to packet-based infrastructures while preserving existing fiber investments.

Technical Specifications and Design Architecture

​​Optical Performance Metrics​​

• ​​Data Rate​​: 155.52 Mbps (OC-3/STM-1), compliant with ​​ITU-T G.957​​ and ​​Telcordia GR-253-CORE​​ standards.
• ​​Wavelength​​: 1310 nm, optimized for multimode fiber (OM1/OM2) with ​​62.5/125 μm core/cladding​​.
• ​​Transmitter Type​​: FP (Fabry-Pérot) laser with -3 dBm to -12 dBm output power.
• ​​Receiver Sensitivity​​: ≤ -28 dBm for error-free operation (BER <1E-12).

​​Hardware Attributes​​

• ​​Form Factor​​: SFP (Small Form-Factor Pluggable) with LC duplex connector.
• ​​Power Consumption​​: 1.2W typical, 1.5W max.
• ​​Operating Temperature​​: 0°C to 70°C (commercial grade).

Key Use Cases and Deployment Scenarios

​​1. Legacy SONET/SDH Network Modernization​​

• ​​Hybrid TDM/Ethernet Transport​​: Aggregate legacy DS-3 and T1 circuits with Ethernet services on shared fiber.
• ​​Graceful Migration​​: Replace PDH microwave links with fiber-based OC-3 connectivity.

​​2. Campus and Metro Access Networks​​

• ​​Building-to-Building Connectivity​​: Link campuses across urban areas without leased lines.
• ​​Fiber to the Tower (FTTT)​​: Backhaul cellular traffic from 4G/LTE base stations to centralized hubs.

​​3. Disaster Recovery and Redundancy​​

• ​​Dark Fiber Activation​​: Deploy backup links using dormant fiber pairs in enterprise conduits.
• ​​Sub-50ms APS (Automatic Protection Switching)​​: Ensure continuity for SCADA and industrial control systems.

Compatibility and Supported Platforms

​​Cisco Hardware Integration​​

• ​​ONS 15454 MSTP​​: Compatible with all SC-1 shelves and TCC2/TCC3 control cards.
• ​​ONS 15310-CL/ONS 15310-MA​​: For edge SONET deployments in remote offices.

​​Software Requirements​​

• ​​Cisco Transport Controller 10.0 or Later​​: For provisioning and performance monitoring.
• ​​TL1/SNMPv2c​​: Integrates with legacy OSS/BSS systems.

Addressing Critical Deployment Questions

​​Q: Can this transceiver interoperate with single-mode fiber?​​

No. The ​​ONS-SI-155-SR-MM=​​ is strictly designed for ​​multimode fiber (MMF)​​. For single-mode applications, use the ​​ONS-SI-155-IR1-MM=​​ variant.

​​Q: What are the limitations for OM3/OM4 fiber?​​

While compatible, OM3/OM4 fibers may extend the reach beyond 2 km due to lower modal dispersion. However, Cisco does not officially certify operation beyond specified limits.

​​Q: How does this module handle signal regeneration?​​

• ​​1R (Reamplification)​​: Boosts optical signals without retiming or reshaping, limiting maximum hop counts to 3–4 spans.
• ​​Chromatic Dispersion Tolerance​​: ≤ 18 ps/nm for error-free performance.

Performance Benchmarks and Reliability

• ​​MTBF​​: 500,000 hours (57 years) based on Telcordia SR-332 Method 1.
• ​​Jitter Generation​​: <1 ps RMS (root mean square) per SONET GR-253 standards.
• ​​Latency​​: <2 μs end-to-end, suitable for real-time industrial protocols like Modbus TCP.

Integration with Cisco’s Management Ecosystem

• ​​Cisco Prime Optical 10.7​​: End-to-end fault isolation and SLA tracking.
• ​​Cross-Platform Alarms​​: Triggers SNMP traps for LOS (Loss of Signal), LOF (Loss of Frame), and BER threshold breaches.

Total Cost of Ownership (TCO) and Licensing

• ​​No License Required​​: Unlike newer coherent modules, this transceiver operates with base ONS software.
• ​​Energy Savings​​: Consumes 80% less power compared to standalone SONET ADMs.

For pricing and availability, visit the [“ONS-SI-155-SR-MM=” link to (https://itmall.sale/product-category/cisco/).

Practical Insights from Field Deployments

In a recent upgrade for a utility company’s SCADA network, the ONS-SI-155-SR-MM= proved indispensable for bridging legacy RTUs (Remote Terminal Units) with modern IP/MPLS cores. However, its reliance on FP lasers introduces challenges in long-term deployments—temperature fluctuations beyond 60°C caused intermittent signal drops until we added auxiliary cooling. For enterprises retaining SONET-trained staff, this module’s familiarity accelerates troubleshooting, but greenfield deployments should consider CPRI-based alternatives for future scalability. The absence of encryption also limits its use in regulated sectors unless paired with external encryptors. Despite these nuances, its plug-and-play simplicity and ​​sub-$500 price point​​ make it a pragmatic choice for budget-constrained, fiber-rich environments.