Cisco ISR4321/K9 4321 Integrated Services Router

The Cisco ISR4321/K9 4321 Integrated Services Router is engineered to meet the growing demands of small enterprise branch offices. It delivers secure, high-performance connectivity and scalable service integration. With an initial system throughput of 50 Mbps and a pay-as-you-grow model that scales up to 100 Mbps via licensing, this router is ideal for businesses seeking flexibility, reliability, and long-term investment protection. Running on Cisco IOS XE, the ISR4321 brings enterprise-grade features such as voice, security, application visibility, and intelligent WAN into a compact, 1U rack-mountable form.

Product Features

Modular and Scalable Architecture

The ISR4321 features a modular design with support for up to two Network Interface Modules (NIMs) and one Integrated Services Card (PVDM4), allowing businesses to expand network capabilities as their needs grow without replacing the hardware.

Advanced Routing and WAN Services

Supports multiple IPv4 and IPv6 routing protocols including OSPF, EIGRP, BGP, and policy-based routing. Application-aware traffic routing is enhanced with Performance Routing (PfR) and Network-Based Application Recognition (NBAR2).

Flexible Throughput Licensing

Comes with 50 Mbps performance by default, with optional upgrade to 100 Mbps via performance licenses (FL-4320-PERF-K9), offering flexibility and cost-efficiency for scaling network demands.

Integrated Security and VPN Support

Includes firewall features, support for IPsec VPN, DMVPN, and FlexVPN, ensuring secure data transmission across multiple branches or remote access locations.

Voice and Collaboration-Ready

With one PVDM4 slot, the ISR4321 supports digital and analog voice capabilities, including FXO, FXS, BRI, and T1/E1 interfaces, enabling businesses to integrate unified communications.

Compact and Power-Efficient Design

Occupying just 1 rack unit, the ISR4321 is suitable for space-constrained deployments and supports PoE with up to 260W power output using PoE Boost for powering phones or access points.

Enhanced LED Monitoring

Front panel includes LED indicators for system health, fan operation, PoE status, and slot activity, offering visual diagnostics for quick hardware monitoring and maintenance.

Product Specifications

• Product Code: Cisco ISR4321/K9
• Form Factor: 1U rackmount or desktop
• Aggregate Throughput: 50 Mbps (default), upgradeable to 100 Mbps
• WAN/LAN Ports: 2 RJ-45 Gigabit Ethernet ports, 1 SFP port
• Management Port: 1 RJ-45 Gigabit Ethernet MGMT port
• Console Ports: 1 RJ-45 and 1 USB Type B mini port
• USB Ports: 1 USB Type A
• Network Interface Module Slots: 2 (single-wide or 1 double-wide)
• Integrated Services Card Slot: 1 PVDM4
• Memory: 4 GB (default), 8 GB (maximum)
• Flash Memory: 4 GB (default), 8 GB (maximum)
• Power Supply: External AC and PoE options
• PoE Support with Boost: Up to 260W
• Dimensions (H x W x D): 44.55 x 369.57 x 294.64 mm
• Package Weight: 9.19 kg

Compatible Modules and Accessories

• Licenses:
  • FL-4320-PERF-K9 (Performance upgrade license)
  • L-SL-4320-APP-K9 (Cisco AppX license with WAAS support)
• Smart Serial Cables:
  • CAB-SS-449FC (RS-449 DCE Female to Smart Serial)
• Console Cables:
  • CAB-CONSOLE-RJ45 (RJ45 to DB9)
  • CAB-CONSOLE-USB (USB Type A to mini-B)
• Network Interface Modules (NIMs):
  • NIM-2CE1T1-PRI (Voice and WAN PRI module)
  • NIM-1MFT-T1/E1 (Multiflex Trunk T1/E1)
  • NIM-4E/M (Analog voice E&M interface)
  • NIM-2FXS, NIM-2FXS/4FXO (Analog voice modules)
• SFP Modules:
  • GLC-LH-SMD (1000BASE-LX/LH)
  • GLC-ZX-SMD (1000BASE-ZX)
  • GLC-SX-MMD (1000BASE-SX)