there is software to simulate any arbitrarily complex network: GNS3, eve-ng, Cisco Modeling labs, etc

I'm talking about heterogenous legacy hardware that isn't owned by Cisco, not complex topologies.

	▲	bijowo1676 26 minutes ago \| parent [-]
		Cisco doesn't talk to devices, Cisco talks protocols, most of them are documented in specs and they are often vendor neutral. if any hardware does not confirm to specs, thats on them and its actually a reason to pull out and replace legacy hw