Cisco IOS-On-UNIX(IOU) is an internal Cisco application used by engineers for testing, proof-of-concept, and validating design.
This is the Linux-based version. It is similar in function to Dynamips/Dynagen/GNS3, but nowhere near as CPU/memory intensive.
This is a VM version with "i86bi_linux-adventerprisek9-ms" and "i86bi_linuxl2-upk9-ms" and support bridge.
thanks dear flyxj