Cisco ASA5585-NM-20-1GE: The Essential Expansion Module for Firewall Power

Jun 11 , 2025 9

ASA5585-NM-20-1GE: The Essential Expansion Module for Firewall Power

Looking to boost your Cisco ASA 5585-X series firewall’s connectivity? The ASA5585-NM-20-1GE module is a critical piece of hardware, but understanding its specifics is key before integrating it. Here’s a detailed breakdown focusing on its capabilities and practical aspects:

1. Core Function & Identity:

• The ASA5585-NM-20-1GE is a dedicated 20-port Gigabit Ethernet Expansion Module designed exclusively for Cisco's ASA 5585-X series next-generation firewalls.

• It plugs directly into the appliance's expansion slot, instantly adding 20 physical 10/100/1000 Mbps copper Ethernet ports to the base configuration. This is invaluable for environments demanding numerous physical connections (e.g., DMZ segments, internal network zones, multiple ISP uplinks).

2. Performance Impact:

• Processing: As an interface module, it doesn't possess its own separate CPU or RAM. Its performance is intrinsically tied to the host ASA 5585-X model (SSP-10, -20, -40, -60). Adding ports doesn't inherently slow down the firewall, but the aggregated traffic load flowing through all interfaces (including these new ports) is processed by the firewall's main SSP.

• Storage: The module contains no significant storage capacity; configuration resides on the firewall's main storage.

• Handling Traffic: It provides line-rate throughput (1 Gbps per port) for switching/routing traffic internally within the firewall. The critical performance bottleneck remains the firewall's SSP processing capacity for inspecting/securing traffic passing through the appliance to other segments.

3. Key Functional Capabilities:

• Provides 20 additional Layer 2/Layer 3 capable Ethernet interfaces.

• Supports all standard ASA interface features: security levels, VLAN tagging (802.1Q), IP addressing, access-control, routing protocols, failover, etc.

• Enables high port density for complex network segmentation and service isolation without needing external switches for basic connectivity.

4. Design & Physical Attributes:

• Form Factor: A compact, hot-swappable module designed to fit seamlessly into the dedicated slot on the rear of the ASA 5585-X chassis.

• Port Layout: Features 20 RJ-45 ports arranged horizontally on the module's faceplate.

• Indicators: Standard per-port status LEDs (Link/Activity) and a module status LED. Clean, functional design prioritizing port density.

5. User Experience Considerations:

• Installation: Relatively simple physical installation (slide into slot, secure with screws). Configuration is done entirely within the ASA's OS (ASDM or CLI) like any other interface.

• Cabling: Managing 20 cables requires careful planning for airflow and organization within the rack. High-density RJ-45 ports are closely spaced.

• Heat & Noise: Adds slightly to the overall thermal load of the chassis, potentially causing fans to spin slightly faster/noticeably under high ambient temps, but usually not a major increase over the base appliance noise.

6. Price Point:

• Primarily available on the secondary/refurbished market (Cisco End-of-Sale). Prices fluctuate significantly based on demand, seller, and warranty offered (e.g., 500 - 1500 USD range is common, but always verify current market value).

• Value Proposition: Offers the most cost-effective way to add a large number of ports directly to the firewall chassis compared to buying an external managed switch and consuming valuable appliance data ports.

7. Battery Consumption:

• Not Applicable. As a line-powered internal module within a larger AC/DC powered appliance, the ASA5585-NM-20-1GE itself has no battery.

8. Compatibility & Expansion:

• Essential Compatibility: Works only with Cisco ASA 5585-X models (ASA5585-X, ASA5585-X SSP-10/20/40/60). Not compatible with any other ASA model or Cisco product line.

• Software Compatibility: Requires ASA OS versions that support the ASA 5585-X platform. Generally compatible with all common 8.x/9.x versions used on these models.

• Expansion Limitations: This is an interface module. Its function is port expansion on the firewall itself. It does not enable adding other types of modules (e.g., you cannot plug another card into this module).

9. Software Support & Firmware:

• Managed entirely through the host ASA's operating system (Cisco ASA OS). No separate firmware downloads or management for the module itself.

• Configuration and monitoring are done using the standard ASA tools: Cisco Adaptive Security Device Manager (ASDM) GUI or the Command-Line Interface (CLI).

• End-of-Sale/Support: As the ASA 5585-X platform is End-of-Sale and End-of-Support, new features or bug fixes specifically for this module from Cisco are highly unlikely. Relies on stable mature code within supported ASA OS versions for the platform.

Conclusion:

The Cisco ASA5585-NM-20-1GE is the definitive solution for maximizing physical port density directly on your ASA 5585-X firewall. If your deployment requires connecting numerous networks or devices without using external switches, this module is indispensable. Its value lies in its high port density, direct integration, and relatively lower secondary market cost compared to external alternatives. Just remember that ultimate firewall throughput is governed by your chosen SSP, and ensure strict compatibility with your ASA 5585-X model before purchasing. For administrators managing complex network segmentation on this platform, the -NM-20-1GE remains a highly practical upgrade.