Cisco ISR4431/K9 Enterprise Router – High-Performance Edge Routing

What It Is

The Cisco ISR4431/K9 is an enterprise-class integrated services router from the Cisco ISR 4000 series. It is designed for medium-to-large branch offices and campus edge deployments, offering modular hardware expansion and integrated IP base (IPB) software features. This model provides a balance of performance, modularity, and security-ready architecture for WAN aggregation and multi-service routing.

Technical Details

• Form Factor: 2 RU modular router with 4 built-in Gigabit Ethernet (GE) ports.
• Network Interface Slots: 3 Network Interface Module (NIM) slots for adding WAN, LAN, or service modules.
• Default Memory: 4 GB DRAM (upgradable), 8 GB flash storage.
• Software Feature Set: IP Base (IPB) license, supporting advanced routing and basic security functions.
• Modular Expansion: NIM slots support a wide range of interface types, including Ethernet, serial, and T1/E1.
• Performance Class: Suitable for concurrent services such as routing, VPN, and firewall at moderate throughput rates.
• Chassis Capacity: Designed for high-availability with redundant power supply options (not included).

Configuration & Options

• Included: Cisco ISR4431/K9 chassis with 4 GE ports, 3 NIM slots, 8 GB flash, 4 GB DRAM, and IP Base software.
• Memory Upgrade: Optional expansion to 8 GB DRAM for increased performance under heavy service load.
• NIM Modules: Compatible with Cisco NIM series modules for additional Ethernet, WAN, or voice interfaces.
• Software Upgrades: Optional license upgrades (e.g., Security, AppX) available for enhanced feature sets.
• Power Supplies: Supports external or internal redundant AC/DC power options (sold separately).

Operating Conditions

The Cisco ISR4431/K9 is optimized for deployment in enterprise branch offices, regional offices, or as a head-end router for smaller remote sites. It operates in controlled indoor environments (standard rack-mount, telecom rooms or server closets) with typical temperature ranges for enterprise equipment. The modular NIM slots allow adaptation to changing network requirements without full hardware replacement, making it suitable for evolving WAN environments.