I will give a short list of popular network emulators and network equipment:
GNS3
www.gns3.com
Open vSwitch
www.openvswitch.org
UNetLab http://www.routereflector.com/unetlab/
EVE-NG www.eve-ng.com
Cisco Packet Tracer
https://www.netacad.com/ru/courses/packet-tracer
Mininet
mininet.org
Huawei eNSP
HP Network Simulator