Cisco ISR 4000 Series Integrated Services Router ISR4331/K9

The Cisco ISR 4000 Series Integrated Services Router ISR4331/K9 delivers enterprise-grade routing, security, and WAN connectivity designed for medium to large branch offices and distributed enterprise locations. This modular platform combines high-performance routing with integrated security services, application optimization, and flexible connectivity options in a single resilient device. Moreover, the ISR4331/K9 provides the foundation for secure digital transformation initiatives, thereby enabling businesses to deploy advanced services including SD-WAN, unified communications, and cloud applications across distributed network infrastructures.

Key Features & Benefits

• High-Performance Routing Engine: Delivers up to 300 Mbps aggregate throughput with advanced security services enabled, supporting bandwidth-intensive applications without performance degradation. Consequently, branch offices can run multiple concurrent services including firewall inspection, VPN encryption, and application visibility while maintaining consistent network performance.
• Modular Network Interface Cards (NIMs): Supports three front-panel NIM slots accepting various interface modules including Ethernet, serial, T1/E1, and wireless connectivity options. Furthermore, this modularity allows businesses to customize router configurations based on specific connectivity requirements and adapt to changing network demands without replacing the entire platform.
• Integrated Security Services: Includes embedded security features supporting Cisco IOS Zone-Based Firewall, IPsec VPN, and advanced threat protection through optional subscription services. As a result, organizations consolidate multiple security functions into a single platform, reducing hardware costs and simplifying security policy management across distributed locations.
• Redundant Power Supply Options: Accommodates optional secondary power supply module for critical deployments requiring maximum uptime and service continuity. Therefore, businesses in industries such as retail, healthcare, and financial services can maintain network connectivity during power failures or planned maintenance activities.
• SD-WAN and Application Optimization: Supports Cisco SD-WAN capabilities with application-aware routing, dynamic path selection, and centralized policy management. In addition, integrated application optimization features including WAAS (Wide Area Application Services) improve performance for cloud-based applications and reduce WAN bandwidth consumption for distributed file sharing.

Technical Specifications

Performance & Capacity

• Throughput: Up to 300 Mbps aggregate with firewall and IPS enabled
• Maximum Throughput: 100 Mbps IPsec VPN, 300 Mbps stateful firewall
• Routing Capacity: 2.5 million packets per second (PPS)
• Maximum Sessions: 250,000 concurrent sessions
• VLANs: Up to 4096 VLAN interfaces supported
• Routing Protocols: BGP, OSPF, EIGRP, RIP, IS-IS, static routing

Interface Options

• Built-in Interfaces: 3x Gigabit Ethernet (RJ-45) WAN/LAN ports
• Service Module Slots: 1x SM-X slot for service modules
• NIM Slots: 3x front-accessible slots for Network Interface Modules
• USB Ports: 2x USB 3.0 ports (console, storage, cellular failover)
• Console/Management: RJ-45 console port, auxiliary port

Memory & Processing

• Processor: Quad-core x86 CPU
• DRAM: 4 GB default (upgradeable to 16 GB)
• Flash Storage: 8 GB eUSB (embedded USB storage)
• Disk Storage: Optional internal SSD storage available

Power & Environmental

• Power Supply: AC 250W internal power supply (redundant option available)
• Power Consumption: Typical 58W, maximum 110W
• Input Voltage: 100-240V AC, 50-60Hz auto-sensing
• Operating Temperature: 0°C to 40°C (32°F to 104°F)
• Operating Humidity: 10% to 85% non-condensing
• Cooling: Front-to-back or side-to-side airflow options

Physical Specifications

• Dimensions: 440mm x 442mm x 87mm (17.3″ x 17.4″ x 3.4″)
• Rack Height: 2RU (two rack units)
• Weight: 7.35 kg (16.2 lbs) without modules
• Mounting: 19-inch rack-mountable with included hardware

Certifications & Compliance

• Safety: UL 60950-1, IEC 60950-1, EN 60950-1
• EMC: FCC Part 15 Class A, VCCI Class A, EN 55022 Class A, CISPR22 Class A
• Environmental: RoHS compliant
• Network Standards: IEEE 802.3, 802.1Q, 802.1p

Security Features

• VPN: IPsec, SSL VPN, DMVPN, FlexVPN, GET VPN
• Firewall: Zone-Based Firewall (ZBFW), stateful packet inspection
• Authentication: RADIUS, TACACS+, 802.1X
• Encryption: AES 128/192/256-bit, 3DES, DES
• Optional Services: Cisco Advanced Malware Protection (AMP), Threat Defense

Software & Licensing

• Operating System: Cisco IOS XE Software
• Base License: IP Base (included)
• Optional Licenses: Security, Application Experience (AX), Unified Communications (UC)
• Management: Cisco DNA Center, Cisco Prime Infrastructure, CLI, web GUI

Use Cases & Applications

Medium to Large Branch Offices

The ISR4331/K9 serves as the primary WAN edge router for branch offices supporting 100-250 users with diverse connectivity requirements. Additionally, the three NIM slots accommodate combinations of broadband, MPLS, and LTE backup connections for business continuity. Furthermore, integrated security services eliminate the need for separate firewall appliances, reducing equipment costs and rack space requirements at remote locations.

Retail Store Networks

Retail organizations deploy the Cisco ISR4331 at regional stores requiring secure connectivity for point-of-sale systems, inventory management, and customer WiFi services. Moreover, the router’s performance capacity handles credit card transaction encryption, video surveillance traffic, and guest internet access simultaneously without service degradation. Specifically, the optional redundant power supply ensures continuous payment processing capability during utility interruptions.

Healthcare Facility Networks

Medical clinics, urgent care centers, and regional healthcare facilities utilize the ISR4331 for HIPAA-compliant network infrastructure supporting electronic health records and medical imaging applications. Notably, the integrated security features provide encryption and access control necessary for protecting patient data across WAN connections. Meanwhile, quality of service (QoS) capabilities prioritize telemedicine video sessions and critical clinical applications over general internet traffic.

Manufacturing Plant Connectivity

Industrial facilities leverage the ISR4331 to connect production systems, warehouse management applications, and enterprise resource planning (ERP) platforms across WAN infrastructure. Additionally, the router supports industrial protocols and SCADA communications while maintaining separation between operational technology (OT) and information technology (IT) networks through VLAN segmentation. Therefore, manufacturing organizations can modernize plant connectivity without compromising production system security or reliability.

Financial Services Branch Locations

Banks, credit unions, and financial advisory offices deploy the Cisco ISR4331 for secure branch connectivity supporting regulatory compliance requirements and customer-facing applications. Furthermore, the platform’s high-performance VPN capabilities protect financial transaction data traversing public internet connections. In addition, the router integrates with Cisco Identity Services Engine (ISE) for network access control, ensuring only authorized devices access sensitive financial systems.

Educational Campus Networks

Universities and large school districts implement the ISR4331 at distributed campus locations requiring resilient connectivity to central data centers and internet services. Specifically, the modular design accommodates diverse connectivity requirements including fiber Ethernet, broadband, and cellular backup across multiple campus buildings. Moreover, the router supports large numbers of concurrent VPN sessions for remote learning initiatives and staff telework programs.

Management & Deployment

The Cisco ISR 4000 Series integrates seamlessly with Cisco DNA Center for intent-based networking, providing automated provisioning, policy enforcement, and lifecycle management across distributed router populations. Consequently, IT teams can deploy configuration changes, security updates, and feature enhancements centrally without manual intervention at each branch location. For organizations implementing SD-WAN initiatives, the ISR4331 supports Cisco SD-WAN architecture with vManage orchestration, enabling application-aware routing and zero-touch deployment for new sites. Additionally, traditional management methods including CLI access, web-based GUI, and SNMP integration remain available for organizations preferring conventional network administration approaches. Furthermore, the router’s modular architecture supports field upgrades and service expansions without service interruptions, thereby protecting initial hardware investments while accommodating evolving business requirements over the platform’s operational lifecycle.