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The Cisco ISR4451 routers are part of the Cisco 4000 Family of Cisco integrated routers, delivering a robust, all-in-one edge platform for branch offices and small-to-midsize enterprises.
Built on Cisco IOS XE software and a multicore x86 architecture, the ISR4451 supports up to 1 Gbps of default encrypted throughput and can be upgraded to 2 Gbps with a performance license, making it an ideal choice for demanding WAN environments.
With on-box SD-WAN, advanced security services, and flexible modularity, these enterprise-grade routers enable secure, high-performance connectivity and application convergence in a compact 1 RU form factor.
Product Overview
Specification
| Feature | Cisco ISR4451-X/K9 |
| Default Aggregate Throughput | 1 Gbps |
| Performance License Throughput | 2 Gbps |
| CEF-Only (Boost License) Throughput | > 4 Gbps |
| Onboard 10/100/1000 Ports (RJ-45) | 4 |
| Onboard 1 Gbps SFP Ports | 4 |
| Enhanced SM-X Service-Module Slots | 2 |
| Doublewide SM-X Slots | 1 (when no singlewide SM-X installed) |
| NIM Slots | 3 |
| Onboard ISC Slot | 1 |
| DRAM (Default) | Data-Plane: 2 GB; Control/Services: 4 GB |
| DRAM (Maximum) | Data-Plane: 2 GB; Control/Services: 16 GB |
| Flash Memory (Default/Max) | 8 GB / 32 GB |
| CPU Architecture | Multicore x86 |
| Embedded Security & SD-WAN | SD-WAN, IPsec, optional NGFW/IPS/AMP, URLF |
| Form Factor | 1 RU rack-mount |
Core Features
-
Multicore x86 Architecture
The ISR4451’s multicore processor separates control, data, and services planes. This ensures consistent routing performance even when running multiple on-box services, such as Cisco Catalyst SD-WAN and advanced security features, concurrently. -
High Throughput with Flexible Licensing
Out of the box, the router delivers up to 1 Gbps of IPsec VPN throughput. A simple license upgrade doubles this to 2 Gbps, and an optional boost license unlocks over 4 Gbps of CEF-only throughput for raw routing performance. -
Integrated SD-WAN and Advanced Security
Cisco Catalyst SD-WAN services offer policy-driven overlay tunnels and intelligent path selection across MPLS, broadband, and LTE links. Optional on-box security bundles provide NGFW, Snort IPS, Cisco AMP, and URL Filtering for unified threat defense. -
Modular Expansion Slots
Three NIM slots, two Enhanced SM-X slots, and one Integrated Services Card (ISC) slot accommodate WAN interface modules, voice DSP modules (PVDM4), storage expansions, and containerized applications, all with Online Insertion and Removal (OIR) support. -
Comprehensive Memory and Storage
Separate control/services and data-plane DRAM planes (4 GB and 2 GB default) can be upgraded independently for optimized performance. Flash memory can be expanded from 8 GB to 32 GB to support large configurations, logs, and on-box VNFs. -
Trustworthy Solutions
Secure Boot, hardware Root of Trust, and Secure Unique Device Identification (SUDI) ensure platform integrity from factory to runtime, mitigating supply-chain and runtime threats. -
Zero-Touch Provisioning & Automation
Integration with Cisco DNA Center and Plug-and-Play capability enables automated onboarding, configuration, and lifecycle management, reducing branch deployment time by up to 70%. -
Scalable SD-WAN Overlay Tunnels
Supports up to 2,500 SD-WAN tunnels for secure, application-aware connectivity, allowing consolidation of multiple branch sites and optimized traffic steering.
Competitor Comparison
| Capability | Cisco ISR4451 | FortiGate 200E | Juniper SRX 1500 |
| IPsec VPN Throughput | 2 Gbps (perf. license); > 4 Gbps CEF | 10 Gbps | 7 Gbps |
| SD-WAN Support | Cisco Catalyst SD-WAN | FortiOS Secure SD-WAN | Juniper Secure Connect |
| Embedded Security | NGFW, IPS, AMP, URLF (on-box) | NGFW, IPS, Antivirus, SD-WAN | NGFW, IPS, UTM |
| Modular Expansion | 3 NIM, 2 SM-X, 1 ISC slot | Fixed appliance | 2 service cards |
| Management Platforms | Cisco DNA Center, CLI, SNMP | FortiManager, FortiCloud | Juniper Mist, CLI |
| Form Factor | 1 RU rack-mount | Desktop/1 RU optional rack | 1 RU rack |
Installation and Setup
Technical Guides
Site Survey & Rack Planning
- Assess available rack space and power (AC/DC), and plan for module slot usage (NIM, SM-X, ISC).
- Ensure adequate airflow and cable management for optimal thermal performance.
License Activation
- Use license install flash:performance.lic to enable higher throughput.
- Enable security services with license boot module isr4451 sec; reload to activate NGFW/IPS/AMP.
SD-WAN Overlay Configuration
sdwan
overlay name branch-overlay
exit
interface GigabitEthernet0/2
sdwan transport interface color biz-internet
no shutdown
Security Policy Deployment
security
ip inspect name NGFW policy
inspect ngfw
url-filtering enable
malware-defense enable
exit
Module Installation (OIR)
hw-module subslot 0 power off
install module SM-X-4G-LTE
hw-module subslot 0 power on
Memory Upgrade
- Insert matched 8 GB DDR3 ECC DIMMs in pairs for control plane memory expansion to 16 GB.
- Verify with show platform hardware memory status.
Firmware Maintenance
Schedule rolling IOS XE updates via Cisco DNA Center or:
request platform software package install profile dna
CLI Configuration Examples
Enable and Enter SD-WAN Configuration
configure terminal
sdwan
Create SD-WAN Overlay
configure terminal
sdwan
overlay name branch-overlay
Configure WAN Interfaces
configure terminal
interface GigabitEthernet0/2
description Internet-Link
sdwan transport interface color biz-internet
no shutdown
Apply IPsec Profile to Tunnel
configure terminal
crypto ikev2 proposal ipsec-prop
encryption aes-gcm
integrity sha256
exit
crypto ipsec profile ipsec-profile
set ikev2 ipsec-prop ipsec-prop
exit
interface Tunnel0
ip address 10.1.1.1 255.255.255.252
tunnel source GigabitEthernet0/2
tunnel mode ipsec ipv4
tunnel protection ipsec profile ipsec-profile
Activate Next-Gen Firewall
configure terminal
license boot module isr4451 sec
security
Real Case Studies and Scenarios
-
Global Retail Chain
A multinational retailer deployed ISR4451-X in 300 stores. Zero-touch provisioning via Cisco DNA Center reduced rollout time by 60%, and SD-WAN multiplexed broadband and LTE links for sub-second failover, ensuring uninterrupted point-of-sale services. -
Healthcare Campus WAN Consolidation
A major hospital integrated ISR4451-X with on-box NGFW and Cisco Umbrella SIG for HIPAA-compliant security. With 2 Gbps aggregate throughput, they supported real-time telemedicine, electronic health records access, and medical IoT devices without latency. -
Financial Services Branch Network
A regional bank replaced legacy routers with ISR4451-X to run containerized compliance and analytics apps. The multicore architecture offloaded services to the programmable plane, improving transaction processing times by 40% during peak hours.
Frequently Asked Questions (FAQs)
-
What is the default and maximum throughput of the Cisco ISR4451?
The router delivers 1 Gbps by default and can be upgraded to 2 Gbps with a performance license; an optional boost license unlocks > 4 Gbps of raw routing throughput. -
How many WAN/LAN ports are onboard?
It includes 4× 10/100/1000 RJ-45 ports and 4× 1 Gbps SFP ports for flexible WAN or LAN connectivity. -
What expansion slots does the ISR4451 offer?
Three NIM slots, two Enhanced SM-X slots, and one Integrated Services Card (ISC) slot support expandable interfaces and services. -
Which security services can I run on-box?
Optional container-based NGFW, Snort IPS, Cisco AMP, and URL Filtering are available via the Security bundle. -
Does the router support SD-WAN?
Yes—Cisco Catalyst SD-WAN is fully integrated, enabling policy-driven overlay tunnels and zero-touch provisioning. -
How much memory and storage can be installed?
Default 2 GB data-plane and 4 GB control-plane DRAM can be upgraded (control-plane to 16 GB). Flash can be expanded from 8 GB to 32 GB. -
What management options are available?
Manage via Cisco DNA Center, CLI, SNMP, REST APIs, or Embedded Event Manager for comprehensive automation and analytics.
Conclusion
The Cisco ISR4451 integrated routers deliver a premium enterprise-grade router platform, combining high-performance routing, SD-WAN, and advanced security in a modular, compact package.
With pay-as-you-grow licensing, multicore performance, and extensive expansion slots, the ISR4451 scales to meet evolving branch office requirements.
Integrated with Cisco DNA Center for zero-touch deployment and automated lifecycle management, this wired router simplifies operations while ensuring robust, secure connectivity for today’s digital-first enterprises.
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