Cisco ISR4331/K9 4331 Integrated Services Router

Cisco ISR4331/K9 is a high-performance branch-office router from Cisco’s 4000 Series, designed to deliver integrated networking and security services in a compact 1-RU form factor. It offers modular interface flexibility, predictable throughput in the 100 Mbps to 300 Mbps range, and is ideal for enterprise edge deployments, including WAN access, SD-WAN, VPN termination, firewalling, and unified communications.

Product Features

Modular Interface Architecture

The ISR4331/K9 features multiple slots (2 NIM modules + 1 SM-X enhanced service module slot) for scalability and flexibility in deploying WAN, LAN, wireless, or security modules.

Predictable Performance with Integrated Services

Rated for aggregate throughput of between 100 Mbps and 300 Mbps (depending on licensed performance level) with integrated services such as firewall, NAT, IPS, application visibility — enabling consistent branch performance under load.

On-board WAN/LAN Ports & Slots for Expansion

The router includes 3 onboard 10/100/1000 ports (2 RJ-45 + 2 SFP with one combo port) and supports expansion via NIM/SM-X modules.

Enterprise-Grade OS & Features

Runs Cisco IOS XE, supports advanced features such as SD-WAN, encryption, segmentation, embedded compute for virtualized services (NFV), making it well-suited for modern branch infrastructure.

Compact and Rack-Mountable Design

Fits in a 1 RU chassis (~44 mm × 438 mm × 438 mm), making it suitable for wiring closets or branch office deployments.

Product Specifications

• Model: ISR4331/K9
• Aggregate Throughput: 100 Mbps to 300 Mbps
• On-board LAN/WAN Ports: 3 × 10/100/1000 (2 RJ-45 + 2 SFP combo)
• Expansion Slots:
  • 1 × SM-X (Enhanced Service Module) slot
  • 2 × NIM (Network Interface Module) slots
• Default Memory: 4 GB DRAM, upgradable to 16 GB
• Default Flash: 4 GB, up to 16 GB
• Form Factor / Dimensions: 1 RU; approx. 44.45 mm H × 438.15 mm W × 438.15 mm D
• Power Supply Options: Internal AC (with a DC variant SKU available)
• Lifecycle Status: End-of-Sale announced (Nov 07 2023) and End-of-Support expected Nov 30 2028.