ISR4321/K9 – 2×GE WAN/LAN Ports – 2×NIM Slots – ISR 4321 Router
9/mo Solds
Established Global IT Distributor
With over a decade of industry experience, we are a certified Cisco Partner delivering genuine enterprise networking hardware and trusted services to system integrators, ISPs, and enterprises worldwide.
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
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.
Application Scenarios
Provides secure VPN connectivity, optional LTE backup, and PoE-enabled EtherSwitch modules to support POS systems, surveillance, and wireless access in small stores.
Offers resilient WAN access with encrypted VPN, while voice NIMs ensure local telephony continuity for mission-critical environments with limited IT staff.
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
|
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 |
Product Comparison
|
Feature |
ISR4321/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
Need pricing, stock, or shipping details for the ISR4321/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.
Quality Certifications
Customer Reviews
Questions & Answers
-
What is ISR4321/K9 used for?
-
What throughput tier does ISR4321/K9 occupy?
-
How many onboard Gigabit Ethernet ports does ISR4321/K9 have?
-
What expansion slots are available on ISR4321/K9?
-
How is ISR4321/K9 different from ISR4221/K9?
-
How is ISR4321/K9 different from ISR4331/K9?
-
Can ISR4321/K9 run SD-WAN?
-
What memory and flash are listed for ISR4321/K9?
Warranty
Layer23-Switch.com offers genuine, high-quality ICT products at competitive wholesale prices—ensuring exceptional value without compromising quality.
All items are brand new, original, and factory-sealed.
Upon request, each unit can be fully tested and verified by a Cisco CCIE-certified engineer to ensure perfect working condition before shipment.
Our Cisco CCIE-certified experts provide free professional support via phone, email, online chat, or remote login—helping you deploy and troubleshoot with confidence.
If you are not satisfied with your purchase, you may request an exchange or full refund. Our customer service team will guide you through the return process quickly and smoothly. Visit Return Policy page for more information.
We support multiple secure payment and logistics options, backed by industry-leading verification:
Visit How to Pay page for more information
Extended, Worry-Free Warranty Coverage Factory New Sealed Enterprise Hardware:
· 3 Years Factory New Sealed
Visit Warranty Policy page for more information
Verify, plan, and comparewith confidence
Use practical tools to check device details, review lifecyclemilestones, and compare hardware before you buy.
Standard Services
Personalized Service, Superior Product Maintenance for Ultimate Satisfaction.
- Projects and Technical Support
- Easy Purchasing Supply
- Product Lifecycle Protection
- Exclusive F3 Team Support
Customized Support for Your Needs with CCIE, HCIE, HPE ASE, etc.
Glad I found Layer23. They’re now in my regular vendor rotation.
Transparent pricing — no surprises at checkout.
Every piece of hardware we buy goes through an authenticity check. This one was spotless. Minor delay in delivery, but everything was in order.
IT guy installed it quickly. Internet is stable.
Hello, what have we here? A fine router. Good deal.