GNS3 supports many vendors and multiple operating systems from vendors such as Cisco. Learn about the various Cisco OS’s like NX-OS, IOSv, IOSvL2, IOS-XRv and others like Arista cEOS, Juniper and more!
Free software worth $200: https://goo.gl/613TUF
Packet Pushers NOS: http://packetpushers.net/virtual-toolbox/list-network-operating-systems/
GNS3 Support (Go here if you need help): https://gns3.com/community