Cisco 4331 (ISR4331/K9) EOL Dates & Catalyst Replacement

Last verified: 2026-10-20

The Cisco 4331 Integrated Services Router (ISR4331/K9) is past its End of Sale date and is no longer receiving standard software maintenance updates. As of October 2026, the hardware remains under routine vulnerability support until its final Last Date of Support (LDoS) on November 30, 2028, at which point all official manufacturer support will cease.

The official replacement for the base ISR4331/K9 is the Catalyst C8200-1N-4T. However, specific feature bundles like the DC-powered variant (ISR4331-DC/K9) have no direct mapped replacement in the official bulletin.

Lifecycle Timeline

These dates apply to the ISR4331 base model and most standard feature bundles as detailed in Cisco Bulletin EOL14896.

Milestone	Date	Status as of Oct 2026
End-of-Life Announcement	November 7, 2022	Past
End of Sale (Hardware & License)	November 7, 2023	Past
Last Ship Date	February 6, 2024	Past
End of New Service Attachment	November 6, 2024	Past
End of SW Maintenance Releases	August 31, 2025	Past
End of Service Contract Renewal	February 5, 2028	Future
Last Date of Support (LDoS)	November 30, 2028	Future

Note: The last supported Cisco IOS-XE release trains for the ISR 4331 are 17.9.x and 17.12.x. Standard EoVSS (vulnerability support) for 17.12 runs until September 2027, followed by ad-hoc patches until the November 2028 LDoS.

Replacement Options

Cisco’s migration strategy moves the ISR 4000 family to the Catalyst 8000 Series Edge Platforms.

Old Part Number	Documented Replacement	Relationship
ISR4331/K9 (Base)	C8200-1N-4T	Official replacement
ISR4331-SEC/K9 (Security Bundle)	C8200-1N-4T	Official replacement
ISR4331-V/K9 (Voice/UC Bundle)	C8200-1N-4T	Official replacement
ISR4331-DC/K9 (DC Power variant)	None	Documentation does not state this
ISR4331/K9	C8300-1N1S-6T / C8300-1N1S-4T2X	Similar / alternative product

Migration Friction & Considerations

In practice, upgrading from the 4331 to the Catalyst 8000 series introduces important operational shifts:

1. Licensing Model Shift: The ISR 4331 utilized perpetual licensing for base IP Base, Security, and UC features. Moving to the Catalyst 8200/8300 requires adopting a Cisco DNA software subscription (Smart Licensing).

2. Hardware Module Compatibility: Existing Network Interface Modules (NIMs) from the ISR 4331 can generally be reused in the Catalyst 8200 and 8300 chassis.

3. Throughput Scaling: While Cisco officially maps the ISR4331 to the C8200-1N-4T, network teams often use the Catalyst C8300 (e.g., C8300-1N1S-6T) as a replacement if the branch has outgrown its original throughput needs or requires 10G WAN interfaces.

4. DC Power Gaps: If you operate the ISR4331-DC/K9, there is no 1:1 replacement explicitly mapped in the EOL bulletin. Buyers will need to review the Catalyst 8200/8300 hardware data sheets to manually spec a DC power supply configuration.

Used Equipment Notes

With the ISR 4331 past its End of Sale but still highly relevant in homelabs and secondary production sites, secondary market availability is high. When purchasing used:

• Verify the exact PID: Distinguish between the base ISR4331/K9 and bundles like ISR4331-SEC/K9 by checking the physical label on the rear or bottom of the chassis.

• Check memory configurations: The base unit shipped with 4GB Flash and 4GB DRAM; many production environments required memory upgrades that may or may not be included by third-party sellers.

FAQ

What is the End of Life date for the Cisco ISR 4331?

The final Last Date of Support (LDoS) for the Cisco ISR 4331 is November 30, 2028.

What replaces the Cisco ISR4331/K9?

Cisco officially recommends the Catalyst C8200-1N-4T router, though the Catalyst C8300 series is frequently used as an alternative for environments needing higher bandwidth or 10G uplinks.

Can I still get software updates for the Cisco 4331?

Standard software maintenance releases ended on August 31, 2025. Only critical vulnerability and security updates are provided for the IOS-XE 17.12.x train until the 2028 LDoS.

Will my 4331 NIM modules work in the replacement router?

Yes, standard Network Interface Modules (NIMs) from the ISR 4000 series are physically compatible with the Catalyst 8200 and 8300 platforms.