ISR4321/K9 – router – rack-mountable

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ISR4321/K9

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List Price: $3827 $378
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Condition New Factory Sealed Related Quantity
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Shipping Express Shipping 2-6 Days, via DHL, FedEx, UPS, etc. Packaging weight and dimensions included:
Weight 3.8 kg
Dimensions 47 × 34 × 12 cm
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ISR4321/K9 Description

Cisco ISR4321/K9, also known as ISR 4321 or Cisco 4321 router, is an enterprise-class branch router within the Cisco 4000 Series. It integrates WAN, security, and voice features in a compact 1RU form factor. The router provides two Gigabit Ethernet combo ports, two NIM slots for WAN, LTE, or EtherSwitch modules, and license-based throughput scalability from 50 to 100 Mbps. With support for unified communications through Voice NIMs, optional PoE via EtherSwitch NIMs, and Cisco IOS XE software, the ISR4321 delivers secure, flexible, and cost-effective performance for small branch offices and retail deployments.

Product Highlights

Aggregate Throughput (Default)
RJ-45-based ports
SFP-based ports

Quick Specs

Parameter

Specification

GE Ports

2 × 10/100/1000 (RJ-45/SFP combo)

NIM Slots

2

SM-X Slot

None

Voice DSP (PVDM4)

Supported via Voice NIMs

Aggregate Throughput

50–100 Mbps (licensed)

Default / Max DRAM

4 GB / 8 GB

Default / Max Flash

4 GB / 8 GB

Power with PoE

Up to 125 W

Rack Units

1 RU

Weight

~4.8 kg

Key Features

Scalable Small-Branch Performance

ISR4321/K9 delivers 50–100 Mbps throughput via flexible performance licensing, ensuring businesses can start with a lower entry cost and upgrade when traffic demands increase.

Modular Expansion for WAN Diversity

Equipped with 2 NIM slots, the router supports a wide range of modules such as LTE, xDSL, serial, PRI/BRI, and EtherSwitch, giving enterprises the ability to adapt quickly to new access technologies.

Reliable Voice and Collaboration Services

By using voice NIMs with onboard PVDM4 DSPs, the router enables SRST, transcoding, and conferencing, helping organizations maintain voice continuity during WAN failures.

Secure WAN Edge with VPN Integration

Hardware-assisted encryption, IPSec VPN, and SD-WAN readiness make the ISR4321 suitable for secure branch connectivity to headquarters or cloud platforms.

Converged Services with PoE Capability

When combined with PoE-capable EtherSwitch NIMs, the router powers IP phones, access points, or cameras, reducing the need for additional PoE switches at small sites.

Compact and Energy-Efficient Design

The 1RU form factor and low power consumption provide space and energy savings, making ISR4321 ideal for space-constrained environments such as retail stores and small branch racks.

Applications Scenarios

Retail and Franchise Branches

Provides secure VPN connectivity, optional LTE backup, and PoE-enabled EtherSwitch modules to support POS systems, surveillance, and wireless access in small stores.

Healthcare Clinics and Financial Kiosks

Offers resilient WAN access with encrypted VPN, while voice NIMs ensure local telephony continuity for mission-critical environments with limited IT staff.

Education and Government Edge Deployments

Ideal for small campuses or local offices that need modular WAN connectivity (DSL, fiber, or cellular), unified communications, and low-cost PoE expansion.

Front View

ISR4321/K9

1

Grounding

2

Power switch

3

Power input connector

4

GE “MGMT” port (with USB port below)

5

USB Type B mini port

6

Console port

7

Auxiliary port

8

GE 0/0/0 (copper cable) port

9

GE 0/0/1 RJ-45 (copper cable) port

10

GE 0/0/0 SFP (fiber-optic) port

Rear View

1

NIM slots

ISR4321/K9

Product Comparison

Feature

ISR4321/K9

ISR4331/K9

ISR4351/K9

GE Ports

2 (RJ-45/SFP combo)

3

3

NIM Slots

2

2

3

SM-X Slot

None

1

1

On-board PVDM/ISC

None

1

1

DRAM Default / Max

4 / 8 GB

4 / 16 GB

4 / 16 GB

Flash Default / Max

4 / 8 GB

4 / 16 GB

4 / 16 GB

Aggregate Throughput

50–100 Mbps

100–300 Mbps

200–400 Mbps

PoE Budget Max

125 W

250 W

500 W

Rack Units

1 RU

1 RU

2 RU

Weight

~4.8 kg

~5.6 kg

~8.4 kg

ISR4321/K9 Supported Modules

Module Type / Part Numbers

Supported on ISR4321/K9

Network Interface Modules (NIMs)

Yes – 2 slots (single-wide or one double-wide with divider removed)

NIM-1GE-CU-SFP / NIM-2GE-CU-SFP

Yes

NIM-1MFT-T1/E1 / NIM-2MFT-T1/E1

Yes

NIM-4MFT-T1/E1 / NIM-8MFT-T1/E1

Yes

NIM-1CE1T1-PRI / NIM-2CE1T1-PRI

Yes

NIM-8CE1T1-PRI

Yes

NIM-ES2-8 / NIM-ES2-8-P

Yes (PoE requires PoE PSU)

NIM-SSD / NIM-HDD

Yes

NIM LTE / xDSL variants

Yes (regional SKUs apply)

Service Modules (SM-X)

Not supported

On-board PVDM4

Not supported (voice DSP provided by voice NIMs)

SFP Modules

Supported (100M/1G SFPs)

Legacy WIC/EHWIC

Not supported

Specifications

Parameter Specification Parameter Specification
Model ISR4321 (Cisco 4000 Series ISR) Form Factor 1RU rack-mount
GE Ports 2 × 10/100/1000 (RJ-45/SFP combo) NIM Slots 2 (single or one double-wide)
SM-X Slot None Voice DSP Via Voice NIM with onboard PVDM4
DRAM Default/Max 4 GB / 8 GB Flash Default/Max 4 GB / 8 GB
Aggregate Throughput 50–100 Mbps (licensed) Encryption Hardware-assisted VPN
USB Ports USB 2.0 Type-A, mini-USB console Console / AUX RJ-45 console, RJ-45 auxiliary
Operating System Cisco IOS XE Power Supply AC default, optional DC PSU
PoE Capability Up to 125 W via EtherSwitch NIM with PoE PSU Cooling Integrated fans
Operating Temp 0–40 °C Humidity 10%–90% non-condensing
Dimensions (H×W×D) 1.75 × 17.25 × 12–13 in Weight ~4.8 kg
Compliance IEC/EN/UL 60950-1/62368-1, CISPR 22/24 Class A Licensing Performance, Security, UC, AppX

Get More Information

Discover unbeatable prices and fast shipping for the ISR4321/K9 Access the detailed ISR4321/K9 datasheet and ensure you’re getting the best deal with our reliable delivery service. Need assistance? Our free live chat support is here to help. For more information about the product and pricing, contact us via Live chat or email us at [email protected]

Quality Certifications

Customer Reviews

Write A Review
5.0
(3 reviews)
5 Stars
3
4 Stars
0
3 Stars
0
2 Stars
0
1 Stars
0
    Office Mgr
    Posted on 25/10/2024
    Verified Buyer
    5.0

    IT guy installed it quickly. Internet is stable.

    Lando Calrissian
    Posted on 10/06/2024
    Verified Buyer
    5.0

    Hello, what have we here? A fine router. Good deal.

    SOHO Consultant
    Posted on 14/02/2024
    Verified Buyer
    5.0

    Small footprint, fanless options available. Good for small offices.

Questions & Answers

  • Where does ISR4321/K9 fit?

    An entry ISR 4000 for small branches needing secure WAN, optional SD-WAN, and basic voice features in a compact form factor.

  • ISR4321 vs ISR4221—how to decide?

    4321 offers more performance headroom. Pick 4221 for very small sites; choose 4321 for slightly heavier VPN or voice needs.

  • Is SD-WAN supported?

    Yes. Operates under Cisco SD-WAN with controller templates or as a traditional ISR with dynamic routing.

  • Voice capabilities?

    Supports CUBE (small session counts), SRST, and voice NIMs for analog integration. Enable QoS for voice priority.

  • Redundancy tips?

    Use dual broadband/MPLS links or LTE backup. Test failover under load to confirm user experience.

  • Management options?

    Web UI for basic provisioning, APIs/Ansible for automation, telemetry for monitoring.

  • Deployment scenarios?

    Small retail, remote offices, and kiosks with modest bandwidth and occasional voice.

  • Licensing advice?

    Right-size SD-WAN, security, and CUBE to avoid over-licensing small sites.

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  • ISR4321-K9 Datasheet

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