I have a standalone (free) esxi 5.1 server that I use to test Cisco VM's. This week I was working with CSR1000v - a virtual router - and the preferred way to connect to it is to add a serial port to the VM, and configure it to use "network serial", configuring the vm as server and a telnet://x.x.x.x:yyyy and enabling the firewall to pass it. Nothing I did seemed to work. Then I changed the license to "demo" and it worked as advertised. I am not using the "virtual serial concentrator" - just the native "network serial" option.
What license would I need to buy to enable this to work? It's just one host, so I don't need any advanced features such as vmotion, distributed vswitch, etc. Just the ability to use a network-based serial port.