ISR4431-AX/K9 – SD-WAN Ready Router for Mid-Branch Optimization
Product Overview
The Cisco ISR4431-AX/K9 is an Application Experience (AX)
integrated services router from the Cisco ISR 4000 Series. It’s
engineered for mid-size enterprise branches that need secure,
intelligent WAN services and application-aware routing. The
included AX license enables advanced features like Application
Visibility and Control (AVC), Performance Routing (PfR), WAN
optimization, and Cisco WAAS. With performance scaling from 500
Mbps to 1 Gbps, the ISR4431-AX/K9 is ideal for hybrid WAN, SD-WAN,
and cloud-ready infrastructure.
Product Details
| Specification | Description |
|---|---|
| Product Code | ISR4431-AX/K9 |
| Series | Cisco ISR 4000 Series |
| Form Factor | 1RU rack-mountable |
| Base Performance | 500 Mbps (upgradable to 1 Gbps via license) |
| Built-in Interfaces | 4 x 1G RJ45 (2 routed, 2 switched), Console, USB |
| NIM Slots | 2 x Network Interface Module slots |
| SM Slots | 1 x Service Module slot |
| DRAM | 4 GB (expandable to 16 GB) |
| Flash Storage | 8 GB (expandable) |
| Power Supply | Optional dual redundant AC/DC |
| Software | Cisco IOS XE |
| AX License Features | AVC, PfR, WAAS, DPI, NBAR2 |
| SD-WAN Support | Yes (via Cisco SD-WAN image) |
| Security Capabilities | ZBFW, IPsec VPN, SSL VPN (via SEC license) |
| High Availability | NSF, ISSU, dual PSU/fans supported |
Product Features
Includes AX license for Application Visibility and Control (AVC), PfR, and WAN optimization
Delivers up to 1 Gbps system performance with software upgrade
Modular with 2 NIM + 1 SM slot for adding voice, LTE, switch, or T1/E1 modules
Cisco IOS XE OS provides SD-WAN, programmability, and software-defined routing
Supports NetFlow, NBAR2, QoS, deep packet inspection, and cloud access control
Ready for hybrid WAN deployments with dynamic traffic path optimization
Highly reliable with hardware redundancy, ISSU, and field-replaceable units
Similar Models Comparison
| Model | AX License | Max Performance | SD-WAN Support | Form Factor | Target Use Case |
|---|---|---|---|---|---|
| ISR4431-AX/K9 | Yes | 1 Gbps | Yes | 1RU | Mid-size branches, cloud edge |
| ISR4451-AX/K9 | Yes | 2 Gbps | Yes | 2RU | Large branches, high-throughput |
| ISR4351-AX/K9 | Yes | 400 Mbps | Yes | 2RU | Medium branch connectivity |
| ISR4331-AX/K9 | Yes | 300 Mbps | Yes | 1RU | Small branch with cloud apps |
Latest AX-Enabled ISR Models Comparison
| Model | Performance Range | Key AX Features | Best Use Case |
|---|---|---|---|
| ISR4431-AX/K9 | 500 Mbps – 1 Gbps | AVC, PfR, WAAS | SD-WAN and hybrid WAN branches |
| ISR4451-AX/K9 | 1 – 2 Gbps | Enhanced optimization | Converged WAN and cloud gateways |
| ISR4331-AX/K9 | 100 – 300 Mbps | Basic AX and NBAR2 | Small branches, basic visibility |
