Cisco 3925 vs ISR 4431
The Cisco 3925 (CISCO3925/K9) is an end-of-life ISR G2; the ISR 4431 (ISR4431/K9) is its modern replacement, delivering 500 Mbps to 1 Gbps of software-licensed throughput, four onboard GE ports, and IOS XE with SD-WAN. For a refresh, move to the ISR 4431.
Cisco 3925 Integrated Services Router
End-of-life ISR G2 enterprise branch router running classic IOS, now beyond last day of support.
- 3 onboard 10/100/1000 RJ-45 ports
- 4 EHWIC slots, 2 SM slots, 3 PVDM3 slots, 1 ISM
- Classic Cisco IOS 15.x, single integrated services CPU
- End of sale and end of support; no further fixes
Cisco ISR 4431
Current high-branch / small-aggregation router with multicore IOS XE and 500 Mbps to 1 Gbps licensed throughput.
- 4 onboard GE ports (combo RJ-45 / SFP)
- 3 NIM slots for modular WAN and services
- 500 Mbps default, upgradable to 1 Gbps via boost license
- IOS XE with Cisco SD-WAN; TAA-compliant options
Cisco 3925 Integrated Services Router vs Cisco ISR 4431: spec comparison
| Spec | Cisco 3925 Integrated Services Router | Cisco ISR 4431 |
|---|---|---|
| Status | End of sale / end of support | Current shipping product |
| Onboard GE ports | 3 x 10/100/1000 RJ-45 | 4 x GE (RJ-45 / SFP combo) |
| Default throughput | Up to ~100-150 Mbps (services on) | 500 Mbps, upgradable to 1 Gbps |
| Modular slots | 4 EHWIC, 2 SM, 3 PVDM3, 1 ISM | 3 NIM (no SM-X on 4431) |
| Software | Classic Cisco IOS 15.x | Cisco IOS XE |
| Control / data plane | Single shared CPU | Separate multicore control and data planes |
| SD-WAN support | No | Yes (Cisco SD-WAN / vManage) |
| Default DRAM / flash | 1 GB DRAM / 256 MB CF | 4 GB DRAM / 8 GB flash (default) |
| Redundant power | Optional internal RPS | Dual internal power supplies supported |
| Rack height | 2RU | 1RU |
| TAA / federal | Legacy, no current TAA SKU | TAA-compliant options, GPC-payable |
Choose Cisco 3925 Integrated Services Router if
Keep the 3925 only to bridge a specific legacy module or feature during a staged migration. With no support contract available, it should not be the basis of any new build.
Choose Cisco ISR 4431 if
Choose the ISR 4431 for enterprise branch refreshes and small aggregation roles that need 500 Mbps to 1 Gbps, four GE ports, and SD-WAN on a supported IOS XE platform.
Verdict
Migrate from the 3925 to the ISR 4431. The 4431 jumps to 500 Mbps to 1 Gbps of licensed throughput, adds a fourth onboard GE port, and runs supported IOS XE with SD-WAN in 1RU. Retain the 3925 only briefly to preserve a legacy module during cutover.
Frequently asked questions
Is the Cisco 3925 end of life?
Yes. The CISCO3925/K9 has reached end of sale and end of support and no longer receives software updates or security patches. Cisco's recommended path is the ISR 4431 in the 4000 family.
What replaces the Cisco 3925?
The ISR 4431 (ISR4431/K9) is the modern replacement, matching the 3925's high-branch role with 500 Mbps to 1 Gbps throughput, four GE ports, and IOS XE.
How much faster is the ISR 4431 than the 3925?
The 4431 ships at 500 Mbps default and licenses up to 1 Gbps, several times the practical throughput of the 3925 with services enabled, thanks to its dedicated multicore data plane.
Does the ISR 4431 take the 3925's EHWIC modules?
No. The 4431 uses NIM modules instead of EHWIC/SM, so plan on new interface modules as part of the upgrade.
More ISR G comparisons
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