Cisco 3900-FANASSY Full English Description

Product Overview

Important Note: The fan assembly supports OIR (Online Insertion and Removal). Complete replacement quickly; prolonged removal will trigger thermal protection and router shutdown. Standard ESD anti-static handling procedures are mandatory during maintenance. This fan assembly cannot be used on 3800 series, 2900 series, ASR series routers or switching platforms.

Key Features

1. Intelligent Variable-Speed Thermal Regulation

   The fan assembly dynamically adjusts fan rotational speed based on real-time internal chassis temperature. Fans operate at low RPM under light load to reduce power draw and acoustic noise, and accelerate automatically to increase airflow when temperatures rise. All thermal telemetry is monitored and reported via Cisco IOS.
2. Front-to-Rear Airflow Architecture

   Cool air enters the router from the front panel, and hot exhaust air flows toward the rear chassis. Keep front and rear ventilation openings unobstructed to avoid airflow restrictions and thermal hotspots.
3. OIR (Online Insertion and Removal) Support

   Field technicians can perform fan assembly replacement while the router remains powered and forwarding traffic. Minimize maintenance duration to prevent over-temperature protection. IOS automatically recognizes and validates the fan hardware after installation.
4. System Monitoring & Alarm Notification

   Cisco IOS continuously monitors the rotation speed of each individual fan rotor.

• Normal status: All fans operate within rated RPM range
• Fault status: The system generates console syslog messages and SNMP traps once fan failure is detected.

1. Internal Fan Redundancy

   Multiple independent fan rotors are built into a single assembly. If one rotor fails, remaining fans provide temporary partial cooling capacity. Network engineers should arrange immediate FRU replacement upon receiving fan fault alerts to avoid unplanned outages.
2. Enterprise-Grade Reliability

   Industrial double-ball bearing DC fans are adopted for stable 24/7 continuous operation in enterprise branch offices, headquarters WAN edge, unified communications voice gateway and remote site networking scenarios.

Supported Hardware Platforms

• Cisco 3925 / 3925E ISR
• Cisco 3945 / 3945E ISR

Not compatible: Cisco 3825, 3845, 2900 series ISR, ASR aggregation routers, Catalyst / Nexus switches.

Typical Application Scenarios

• Enterprise branch WAN, internet edge and voice gateway deployments running Cisco IOS on 3900 ISR G2 routers
• Spare replacement cooling fan assembly for legacy 3925/3945 series routers
• Network maintenance for existing branch infrastructure requiring hot-swappable cooling components

Technical Specifications

• Form Factor: Integrated front fan assembly with metal grille
• Part Number: 3900-FANASSY=
• NEBS Filtered Variant: 3900-FANASSY-NEBS
• Airflow Direction: Front-to-Rear
• Hot Swappable: Yes (OIR supported under Cisco IOS)
• Monitoring: Per-fan RPM monitoring, IOS syslog and SNMP alarm support
• Operating Ambient Temperature: 0°C ~ +40°C
• Compliance: UL, CE, RoHS compliant

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