It is important to note that Cisco IOU images are proprietary software intended only for Cisco's internal use and are not officially available for public download. For legal and ethical lab environments, the recommended alternative is to use , which provides access to officially licensed, up-to-date virtual images.
Download the i86bi-linux-l2-adventerprisek9-15.2d.bin file.
Network professionals prefer IOL images in EVE-NG due to their rapid boot times and low RAM footprint (often requiring only 256MB to 512MB of RAM per node). To use it, the binary is placed in the /opt/unetlab/addons/iol/bin/ directory and requires a valid iourc license file to validate the Cisco process execution. 2. GNS3 (Graphical Network Simulator-3) i86bi-linux-l2-adventerprisek9-15.2d.bin
Fix permissions via the EVE-NG CLI using the command: /opt/unetlab/wrappers/unl_wrapper -a fixpermissions Create your iourc license file in the same directory. 3. Integration in GNS3 To add it to GNS3:
: Full support for PVST+, Rapid-PVST+, and Multiple Spanning Tree (MST). It is important to note that Cisco IOU
: This tag signifies the target hardware platform for which this software image is compiled. In the context of IOU/IOL, i86bi stands for Intel 86 (x86) Boot Image . It indicates that this software is native code meant to run directly on an Intel/AMD (x86) processor's Linux operating system, rather than emulating the hardware of a physical Cisco router.
Specifically, users have reported the following limitations: Network professionals prefer IOL images in EVE-NG due
The file must be executable for the simulation to start. Run the following commands via SSH: Make Executable
Build instructions for setting up a CCIE R&S lab in KVM - GitHub
Compared to VIRL/vIOS images, IOU images are extremely lightweight. You can run 20-30 switches on a laptop with 8GB of RAM.
When building large topologies, resource consumption is the biggest bottleneck. Network emulators allow you to choose between standard IOL images or newer Cisco vIOS images (extracted from Cisco CML/VIRL). Cisco IOL (15.2d.bin) Cisco vIOS-L2 (CML) Native Linux Process Full Virtual Machine (QEMU) RAM Usage ~100 MB – 250 MB per node ~512 MB – 1 GB per node Boot Time Near instantaneous (< 5 seconds) 1 to 3 minutes CPU Overhead Extremely low idle CPU Moderate to high idle CPU Scaling Can easily run 50+ switches on a laptop Limited by RAM/CPU cores