ISR4351 K9 High-Performance Integrated Services Router for Mid-Size Offices
Product Overview
The Cisco ISR4351/K9 is a modular integrated services router from
the Cisco ISR 4000 Series, engineered for medium to large branch
offices. It delivers scalable performance from 200 Mbps to 400 Mbps
(via performance-on-demand licenses), with built-in support for
routing, voice, security, SD-WAN, and virtualized services. With
advanced modularity, it supports multiple NIM and SM slots, making
it ideal for converged data, voice, and WAN connectivity.
Product Details
| Specification | Description |
|---|---|
| Product Code | ISR4351/K9 |
| Series | Cisco ISR 4000 Series |
| Form Factor | 1RU Rack-Mountable |
| Default Throughput | 200 Mbps (upgradable to 400 Mbps with license) |
| Processor | Cisco QuantumFlow Processor |
| Memory (DRAM) | 4 GB (upgradeable to 16 GB) |
| Flash Storage | 8 GB (upgradeable to 32 GB) |
| Integrated GE Ports | 3 x 1G RJ45 + 1 x 1G SFP |
| NIM Slots | 2 |
| SM-X Slots | 1 |
| Voice Support | Optional (via DSP modules and licenses) |
| Redundant Power Support | Yes (optional external RPS) |
| Software | Cisco IOS XE (modular, SD-WAN capable) |
| Virtualization Support | Yes (UCS-E, KVM, Linux containers) |
| SD-WAN Support | Yes |
Product Features
Performance-on-Demand licensing allows scalable throughput (200 → 400 Mbps)
Modular platform with two NIM slots and one SM-X slot for WAN, voice, or LTE modules
Optional voice DSPs and Unified Communications capabilities (CME, SRST)
Full SD-WAN ready with support for segmentation, cloud on-ramp, and app-based routing
Built-in security features: ZBFW, IPsec VPN, AVC, Control Plane Protection
High resiliency with redundant power supply support
Ideal for multi-service branch deployments requiring routing, security, and UC in one box
Similar Models Comparison
| Model | Default Throughput | Max Throughput | NIM Slots | Voice Capable | SD-WAN | Ideal For |
|---|---|---|---|---|---|---|
| ISR4451/K9 | 1 Gbps | 2 Gbps | 3 | Optional | Yes | Large branches |
| ISR4351/K9 | 200 Mbps | 400 Mbps | 2 | Optional | Yes | Medium branches |
| ISR4331/K9 | 100 Mbps | 300 Mbps | 2 | Optional | Yes | Small to medium offices |
Latest ISR 4000 Series Models Overview
| Model | Form Factor | Default/Max Throughput | Voice Support | SD-WAN Ready | Target Use Case |
|---|---|---|---|---|---|
| ISR4451/K9 | 2RU | 1G / 2G | Yes (optional) | Yes | Enterprise-class branch |
| ISR4351/K9 | 1RU | 200M / 400M | Yes (optional) | Yes | Medium multiservice branch |
| ISR4331/K9 | 1RU | 100M / 300M | Yes (optional) | Yes | Small-to-mid branch office |
