Cisco 1941 (CISCO1941/K9) to ISR 4221 Migration Guide

If your branch network still runs on the Cisco 1941 Integrated Services Router (PID CISCO1941/K9), you are operating hardware that is fully past Cisco's support lifecycle. The 1941 reached End-of-Sale on September 29, 2018, lost software maintenance on September 29, 2019, and crossed its Last Day of Support (LDoS) on September 30, 2023. As of today, there is no path to a TAC case, no RMA on a failed unit, and no security fix for any CVE that surfaces against IOS 15.x on this platform. Cisco's own End-of-Life bulletin names the ISR 4221 (PID ISR4221/K9) as the migration target. This guide explains what the milestones actually mean, why the ISR 4221 is a genuine upgrade rather than a like-for-like swap, and how to plan a clean cutover.

Why the 1941's end-of-life status is an active risk, not a someday problem

The 1941 is a dual Gigabit Ethernet ISR Generation 2 branch router built on a multicore PowerPC architecture, with two onboard GE WAN/LAN ports, two EHWIC slots, an ISM/PVDM slot, and software-activation licensing (IP Base, plus Data, SEC, and UC technology packages unlocked by PAK). It was a workhorse for small-site WAN edge for the better part of a decade. That longevity is exactly the problem now: a box this widely deployed is a known, well-documented attack surface, and once a platform is past LDoS, Cisco PSIRT no longer issues fixed releases for it. A new IOS 15 vulnerability that lands tomorrow simply will not be patched on the 1941.

There is also a hard operational risk: with no RMA, a power-supply or board failure on a 1941 means a cold spare from the gray market or an emergency refresh under outage pressure, which is the most expensive and error-prone way to replace anything. See the full lifecycle breakdown on the CISCO1941/K9 EoL detail page.

What each milestone date means in practice

• End-of-Sale (2018-09-29): the last date you could order a 1941 new from Cisco. Anything bought after this is used, refurbished, or remaining channel stock.
• End of Software Maintenance (2019-09-29): the last date Cisco released maintenance rebuilds and bug fixes for IOS on this platform. Releases after this are frozen, so any defect found later stays unfixed.
• Last Day of Support / LDoS (2023-09-30): the hard cutoff. After this date there is no Cisco TAC, no hardware RMA, and no security patching, even with an active service contract. SmartNet cannot be renewed against the chassis.

The takeaway: every 1941 in production today sits past all three milestones. There is no remaining grace period to plan against; the refresh is already overdue.

The recommended replacement: Cisco ISR 4221 (ISR4221/K9)

The ISR 4221 is the bulletin-designated successor and the right baseline replacement for a 1941. It is a member of the ISR 4000 family running IOS-XE rather than classic IOS, and that single change reshapes how the platform is managed, secured, and scaled.

Throughput and architecture

The 1941's real-world forwarding with services enabled (IPsec, NAT, ZBFW, NetFlow) typically landed in the 25-75 Mbps range. The ISR 4221 ships with a default aggregate throughput of 35 Mbps and is software-license-upgradeable to 75 Mbps, 100 Mbps, and up to 2.5 Gbps via a performance license, with no hardware change. The 4221 separates the control plane and data plane on a multicore x86 data-plane engine, so enabling deep services degrades performance far more gracefully than on the 1941's monolithic IOS process. For sites that have outgrown the 1941's ceiling, the throughput headroom alone justifies the move.

Modularity, ports, and PoE

The 4221/K9 base configuration provides two onboard GE RJ45 ports and two Network Interface Module (NIM) slots, plus 8 GB of flash and 4 GB of DRAM, shipped with IP Base. The NIM slot family is the modern equivalent of the 1941's EHWIC slots: it carries serial, T1/E1, xDSL, LTE/5G, and a 4- or 8-port GE switch NIM, and the GE switch NIM can be ordered with PoE/PoE+ for powering a phone or AP at a micro-site. If you have EHWIC modules in your 1941s, plan to repurchase the NIM equivalents; EHWICs are not carried forward.

Licensing: PAK to Smart Licensing, and the path to SD-WAN

This is the biggest operational difference. The 1941 used node-locked PAK activation for its technology packages. The ISR 4221 uses Cisco Smart Licensing, with feature sets delivered through technology packages (Application Experience, Security, and the Unified set) plus a separately licensed performance tier. Smart Licensing pools entitlements at the account level instead of locking them to a serial number, which simplifies RMA and audit reporting. Just as important, the ISR 4221 can run the Cisco SD-WAN (Catalyst SD-WAN, formerly Viptela) image, so the same chassis that replaces a static-routed 1941 can later join a centrally managed, zero-touch-provisioned overlay without a forklift. The 1941 has no SD-WAN path at all.

A practical migration plan

1. Assess and inventory

Pull show inventory, show license, and show running-config from each 1941. Catalog the EHWIC modules in use (serial, T1/E1, ADSL, the HWIC-4ESW switch module), the technology packages activated, and the IOS feature set each site actually depends on. This inventory drives both the NIM bill of materials and the license tier you order on the 4221.

2. Plan license and feature parity

Map each 1941 feature to its IOS-XE equivalent. Most IOS 15 config translates cleanly (interfaces, OSPF/EIGRP/BGP, NAT, ACLs, IPsec), but verify the items that changed names or behavior in IOS-XE: zone-based firewall, NetFlow to Flexible NetFlow, and the move from CLI license activation to Smart Licensing. Decide your throughput tier now so the performance license is on the purchase order, not a follow-on order weeks later.

3. Physical: rack, power, uplinks, optics

The 4221 is a compact 1RU chassis with an internal AC supply, so rack and power planning is straightforward at most branch sites. Confirm NIM population for any serial/T1 circuits, order the matching cables, and if you need fiber uplinks, plan the SFP/optics for the GE ports. If a 1941 was quietly powering a phone or AP through an EHWIC switch module, order the PoE-capable GE switch NIM to preserve that.

4. Phased cutover

Stage and pre-configure 4221s in a lab, validate against a pilot site, then cut over branch by branch during maintenance windows. Keep the 1941 racked but cabled out as an immediate rollback for the first few cutovers. Because the 4221 can run plain IOS-XE first and adopt SD-WAN later, you can decouple the hardware refresh from any overlay migration to reduce change risk.

5. Secure decommission

After cutover, wipe each 1941 (erase startup-config, clear the file system, factory-default) before it leaves the building. For DoD and healthcare environments, document the sanitization to NIST 800-88 and retain the chain-of-custody record. Do not resell or recycle a unit until it is confirmed clean.

Procurement notes for government and enterprise buyers

• TAA compliance: order ISR 4221/K9 units from an authorized partner who can attest to country-of-origin for the chassis and NIMs, which is mandatory for federal and many SLED purchases.
• GPC payment: micro-purchases and single-site refreshes can be placed on the Government Purchase Card through Uniqcli.
• Lead times: ISR 4000 modules and performance licenses can have variable lead times; lock the BOM early and ask for stock visibility rather than assuming overnight availability.
• Authorized sourcing: buying refresh hardware from the authorized channel keeps your new chassis eligible for genuine SmartNet/Smart Net Total Care, which the gray market cannot guarantee.

Uniqcli is an authorized Cisco partner and can scope a like-for-like or higher-throughput 4221 build, confirm TAA compliance, accept the GPC, and plan the cutover. Browse the Cisco router catalog, review other refreshes on the Cisco EoL hub, or skip straight to a tailored bill of materials. Get a refresh quote for your 1941 fleet and we will turn your inventory into a costed migration plan.