ISR4351 AX K9 WAN Optimization and PfR Router
Product Overview
The Cisco ISR4351-AX/K9 is an Application Experience (AX)
integrated services router from the Cisco ISR 4000 Series. Designed
for medium-sized branch offices, it combines routing, application
optimization, and secure WAN connectivity in one modular platform.
With an included AX license, it enables Application Visibility and
Control (AVC), Performance Routing (PfR), and WAN optimization
(WAAS). The ISR4351-AX/K9 delivers modular scalability, SD-WAN
readiness, and QoS-rich performance at 200 Mbps (upgradable to 400
Mbps).
Product Details
| Specification | Description |
|---|---|
| Product Code | ISR4351-AX/K9 |
| Series | Cisco ISR 4000 Series |
| Form Factor | 2RU rack-mountable |
| Base Performance | 200 Mbps (upgradeable to 400 Mbps) |
| Built-in Interfaces | 4 x 1G RJ45, Console, USB |
| NIM Slots | 2 x Network Interface Module slots |
| SM Slots | 2 x Service Module slots |
| 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 (with SD-WAN image) |
| Security Capabilities | IPsec VPN, ZBFW, SSL VPN (with SEC license) |
| Application Performance | Application-aware QoS and path optimization |
| High Availability | NSF, ISSU, dual PSU/fans supported |
Product Features
Includes AX license for application-aware routing and WAN optimization
Supports NBAR2, NetFlow, WAAS, and Performance Routing (PfR)
Modular design with 2 NIM and 2 SM slots for expansion flexibility
Delivers 200–400 Mbps system throughput, ideal for hybrid WANs
Powered by Cisco IOS XE, enabling SD-WAN, telemetry, and programmability
Redundant power options for enterprise-grade resiliency
Ideal for cloud-access edge, application performance monitoring, and secure WAN routing
Similar Models Comparison
| Model | AX License | Max Performance | SD-WAN Ready | NIM/SM Slots | Form Factor |
|---|---|---|---|---|---|
| ISR4351-AX/K9 | Yes | 400 Mbps | Yes | 2 / 2 | 2RU |
| ISR4451-AX/K9 | Yes | 2 Gbps | Yes | 3 / 2 | 2RU |
| ISR4431-AX/K9 | Yes | 1 Gbps | Yes | 2 / 1 | 1RU |
| ISR4331-AX/K9 | Yes | 300 Mbps | Yes | 2 / 1 | 1RU |
Latest AX-Enabled ISR Models Comparison
| Model | Performance Range | Key AX Features | Best Use Case |
|---|---|---|---|
| ISR4351-AX/K9 | 200 – 400 Mbps | AVC, WAAS, PfR | Medium branch, cloud & WAN edge |
| ISR4451-AX/K9 | 1 – 2 Gbps | Enhanced WAN optimization | Large branch or regional HQ |
| ISR4331-AX/K9 | 100 – 300 Mbps | AVC, PfR | Small-to-medium branch deployments |
