Cumulus Linux provides a virtual appliance for testing and development. It’s free to download. The post below shows how to get Cumulus VX up and running in UNL.
During my CCIE studies I used Unetlab for all my lab activities. I found it to be extremely useful for starting up a quick lab with a few routers to work on a specific technology and also for full scale labs – running 30 devices wasn’t an issue.
The Unetlab host runs in a virtual machine or as a bare-metal server and supports IOU, Dynamips and QEMU nodes. The full list of the supported nodes is listed here. Since completing my CCIE I’ve continued to use it for multi-vendor labs, in future I’ll post about some of the other supported vendors, showing how to get their devices up and running.