ASR-9922-DC= Overview

The ​​ASR-9922-DC=​​ is a Cisco-certified DC power shelf designed for the ASR 9922 Router, a high-density platform in the ASR 9000 Series. It provides ​​-48V DC input​​ compatibility, catering to telecom operators and enterprises with legacy DC power infrastructure.

Technical Breakdown: Core Features

• ​​Power Capacity​​: Supports ​​12 kW per shelf​​ (4x 3kW DC PEMs) with N+N redundancy.
• ​​Voltage Range​​: Accepts ​​-40V to -72V DC​​, compatible with global telecom DC standards.
• ​​Hot-Swap Functionality​​: PEMs can be replaced without interrupting router operations.
• ​​Environmental Tolerance​​: Operates at ​​-5°C to 55°C​​, ideal for non-climate-controlled edge sites.

Why This Power Shelf Matters in Modern Networks

• ​​Legacy Infrastructure Integration​​: Enables ASR 9922 deployment in central offices still reliant on DC plants.
• ​​Energy Efficiency​​: Achieves ​​94% conversion efficiency​​, reducing OPEX versus traditional rectifier systems.
• ​​Safety Compliance​​: Meets ​​Telcordia GR-3108​​ and ​​ETSI EN 300 132-3​​ standards for DC installations.

Key Deployment Scenarios

1. ​​Wireless Provider Hub Sites​​: Powers 400G IPoDWDM backhaul routers in 5G networks.
2. ​​Submarine Cable Landing Stations​​: Withstands salt-air corrosion in coastal DC power environments.
3. ​​Industrial IoT Gateways​​: Supports harsh environments like oil refineries with DC backup systems.

Sourcing and Configuration Guidance

While Cisco.com outlines technical requirements, physical validation of components is critical. For assured compatibility, review the ​​ASR-9922-DC= inventory at ITmall.sale​​.

​​Implementation checklist​​:

• Verify DC plant grounding matches Cisco’s ​​ISSU (In-Service Software Upgrade)​​ requirements.
• Confirm breaker ratings (63A minimum per PEM feed).
• Order redundant PEMs as single-unit failures reduce total capacity by 25%.

Addressing Operator Concerns

​​Q: Can this shelf support mixed AC/DC inputs?​​
No—the ASR-9922-DC= is DC-only. Hybrid deployments require separate ASR-9922-AC shelves.

​​Q: What happens during DC voltage drops below -40V?​​
The shelf triggers an alarm and initiates graceful shutdown at ​​-38.5V​​ to prevent hardware damage.

Field Engineer Perspective

In a recent Tier 2 carrier deployment, a “minor” oversight in DC busbar sizing caused a 22-minute outage when PEMs drew simultaneous startup current. The ASR-9922-DC= isn’t just power hardware—it’s a systems engineering challenge. Its value lies not in the shelf itself, but in forcing teams to audit often-neglected DC infrastructure. Those who treat it as a checkbox component risk learning the hard way that even terabit routers are powerless without precision-matched electrons.