ISR4431/K9 – 4×GE WAN/LAN Ports – 3×NIM Slots – ISR 4431 Router
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ISR4431/K9 Description
The Cisco ISR4431/K9 is a high-performance integrated services router designed for medium-to-large branch offices that require scalable throughput and rich service integration. As a key member of the ISR 4000 family, it features a multicore CPU architecture that separates control, data, and service planes. This design ensures that enabling advanced services like firewalling, IPS, or application visibility does not degrade the router's throughput, delivering consistent performance for mission-critical business applications.
Out of the box, the ISR4431 offers a base throughput of 500 Mbps, which can be upgraded to 1 Gbps via a software license, providing a pay-as-you-grow investment model. It comes with four onboard Gigabit Ethernet ports (combo RJ45/SFP), three Network Interface Module (NIM) slots, and support for the Cisco UCS-E server module. This extensive modularity allows the ISR4431 to consolidate branch infrastructure into a single chassis, functioning as a router, voice gateway, firewall, and edge server simultaneously.
Product Highlights
Quick Specs
|
Parameter |
Specification |
|---|---|
|
GE Ports |
4 × 10/100/1000 (RJ-45/SFP mix) |
|
10GE Ports |
None |
|
NIM Slots |
3 |
|
SM-X Slots |
None |
|
On-board PVDM/ISC |
1 |
|
Aggregate Throughput |
500 Mbps (base), up to 1 Gbps (licensed) |
|
Default / Max DRAM |
4 GB / 16 GB |
|
Default / Max Flash |
8 GB / 32 GB |
|
Max Power with PoE |
~250 W |
|
Rack Units |
1 RU |
|
Weight |
~6.2 kg |
Key Features
Provides 500 Mbps base throughput, scalable to 1 Gbps with licensing, supporting bandwidth-heavy branch applications, cloud access, and hybrid WAN designs.
Expands easily with T1/E1, xDSL, LTE, or EtherSwitch NIMs, enabling organizations to tailor WAN, voice, or LAN services to their exact needs.
Supports PVDM4 DSP modules in the onboard ISC, delivering SRST, conferencing, and transcoding for reliable unified communications.
Hardware-accelerated VPN, IPSec, and SD-WAN readiness ensure data security and policy-based segmentation across distributed branch networks.
Up to 16 GB DRAM and 32 GB flash allow greater service density, caching, and support for advanced Cisco IOS XE features without compromising performance.
1RU form factor with integrated cooling, stable operation in enterprise racks, and lower energy use make it efficient for mid-to-large branch environments.
Application Scenarios
Suited for medium and large offices that require resilient WAN connectivity, application-aware routing, and secure VPN to connect to HQ or cloud services.
Delivers reliable multi-service integration, encrypted transactions, and compliance-driven VPN security, ensuring smooth operations in distributed sites.
Enables converged services at the branch edge, providing secure inter-site networking, branch telephony survivability, and modular WAN expansion for mission-critical environments.
Product Comparison
|
Feature |
Cisco ISR4431/K9 (Current Model) |
Cisco ISR4331/K9 (Lower Tier) |
Cisco ISR4451-X/K9 (Higher Tier) |
Cisco 2921/K9 (Legacy EOL) |
|---|---|---|---|---|
|
Throughput (Base/Max) |
500 Mbps / 1 Gbps |
100 Mbps / 300 Mbps |
1 Gbps / 2 Gbps |
~50 Mbps (Max) |
|
Onboard GE Ports |
4 (Combo) |
3 (2x RJ45, 1x Combo) |
4 (Combo) |
3 (RJ45/SFP) |
|
NIM Slots |
3 |
2 |
3 |
4 (EHWIC) |
|
SM-X Slots |
0 |
1 |
2 |
1 (NME) |
|
Rack Height |
1 RU |
1 RU |
2 RU |
2 RU |
|
Default DRAM |
4 GB |
4 GB |
4 GB |
512 MB |
|
Power Supply |
Internal (Redundant Opt) |
Internal (Single) |
Internal (Redundant Opt) |
Internal |
|
SD-WAN Support |
Full |
Full |
Full |
No |
Selection Guide
- Requirement for 500M-1G Throughput
Select the ISR4431 if your branch WAN bandwidth requirements exceed 300 Mbps. Unlike the smaller ISR4331 (capped at 300M), this model scales up to 1 Gbps, providing ample headroom for future fiber internet upgrades. - Voice Integration Needs
If your branch requires a local voice gateway (CUBE/SRST) but does not need the heavy compute of a UCS-E server blade (which requires SM-X slots), the ISR4431 is the cost-effective “sweet spot.” It supports internal DSPs and voice interface cards natively. - No Need for Service Modules (SM-X)
Note that the ISR4431 does not have SM-X slots (unlike the 4331 and 4451). If you plan to install single-wide or double-wide service modules (like high-density switch blades or UCS-E servers), you should choose the ISR4331 or upgrade to the ISR4451. - Power Redundancy Priority
This is the lowest-end model in the ISR 4000 series that supports internal redundant power supplies. If power redundancy is a mandatory compliance requirement for your branch, the ISR4431 is the starting point (the 4300 series only supports single internal PSUs).
Front View
|
1 |
Power supply unit (PSU1) |
2 |
LEDs |
|
3 |
On/Off switch |
4 |
Optional power supply unit (PSU0) |
Chassis View
|
1 |
USB ports |
2 |
GE ports |
|
3 |
Screws to open the NIM slot |
4 |
Router label tray |
|
5 |
NIM slot (with cover) |
6 |
Ground connection |
Specifications
| Parameter | Specification | Parameter | Specification |
|---|---|---|---|
| Model | ISR4431 (Cisco 4000 Series ISR) | Form Factor | 1RU rack-mount |
| GE Ports | 4 × 10/100/1000 | 10GE Ports | None |
| NIM Slots | 3 | SM-X Slots | None |
| On-board ISC | 1 slot for PVDM4 DSPs | USB Ports | 2 × USB 2.0 Type-A, 1 × mini-USB console |
| Console / AUX | RJ-45 console and RJ-45 auxiliary | Operating System | Cisco IOS XE |
| Default / Max DRAM | 4 GB / 16 GB | Default / Max Flash | 8 GB / 32 GB |
| Aggregate Throughput | 500 Mbps (base), 1 Gbps (licensed) | Encryption | Hardware-assisted VPN |
| WAN/LAN via Modules | NIMs for T1/E1, serial, xDSL, LTE, EtherSwitch | SFP Support | 100/1000 Mbps SFPs |
| Power Supply | AC PSU, optional DC | Max PoE Budget | Up to 250 W with PoE PSU |
| Cooling | Integrated fan system | Operating Temp | 0–40 °C |
| Humidity | 5%–85% non-condensing | Altitude | 0–10,000 ft |
| Dimensions (H×W×D) | 1.73 × 17.25 × 19.97 in | Weight | ~6.2 kg |
| Compliance | IEC/EN/UL 60950-1/62368-1, CISPR 22/24 Class A | Licensing | Performance, Security, UC, AppX |
Get More Information
Need pricing, stock, or shipping details for the ISR4431/K9 ? Layer23-Switch can help you check current availability, lead time, and delivery options for this. Send us the part number, quantity, and destination country via live chat or email sales@layer23-switch.com for a fast quotation.
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Customer Reviews
Questions & Answers
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What is ISR4431/K9 used for?
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What throughput tier does ISR4431/K9 occupy?
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How many onboard Gigabit Ethernet ports does ISR4431/K9 have?
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What expansion slots are listed for ISR4431/K9?
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How is ISR4431/K9 different from ISR4351/K9?
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Does ISR4431/K9 support dual power supplies?
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Can ISR4431/K9 run SD-WAN and security services together?
-
What memory is listed for ISR4431/K9?
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