Even in 2026, with EVE-NG and CML dominating the conversation, the classic combination remains one of the most efficient ways to build large-scale Layer 3 topologies on a laptop.
April 17, 2026 | Category: GNS3 Tutorials | Reading Time: 5 minutes Cisco IOU L3 - GNS3
Breathing New Life into Old Labs: A Deep Dive into Cisco IOU L3 on GNS3 Even in 2026, with EVE-NG and CML dominating
IOU requires a license file called iourc . You must place a valid iourc file in the GNS3 config directory (usually ~/.GNS3/ on Linux/Mac or %LOCALAPPDATA%/GNS3 on Windows). A sample iourc entry looks like: [license] hostname = 12345678 Even in 2026