Hosts

•  How does one add hosts to APIC-EM. Got a Linux VM on the same LAN segment as the APIC-EM VM. It is expected that Linux VM to appear as a host, as it seems to fit the definition of what a host should be.
•  The Linux VM does not appear as a host though.
•  The Linux VM is detected in the Device Discovery, and it does have SSH access with a cisco/cisco account, and a cisco/cisco account is configured in global credentials, and those global credentials are configured for the discovery job.
•  Device Control is enabled, but the discovery entry for the  Linux VM is reporting that the SNMP is timing out. Since Device Control is enabled, and the Linux VM can be accessed via the CLI/SSH with global credentials configured for the discovery job, Is it possible that CLI could be used to enable SNMP as required.  Whether that is even relevant to host discovery.
• The host is being seen in the IP range, but that is all. It is not being discovered. The APIC-EM instance and the Linux VM are on the same subnet.

The host can be discovered via CDP/LLDP/IP Device Tracking or SNMP Traps (only for wireless hosts).

The SNMP/CLI credentials are used to discover the network devices only and not the hosts. As mentioned above the hosts that are connected to a network device, will be discovered using CDP/LLDP/IP device tracking . For a linux VM to be discovered as a host, it needs to be connected to a switch where you have "ip device tracking" enabled (assuming it is a wired host).

When you log in to the switch and entering the command:

 show ip device tracking all

 Do you see the IP of the Linux VM.

enable IP device tracking by entering this commands under configuration mode:

 ip device tracking

ip device tracking probe delay 10

 And also had to enable device tracking per-interface with a hidden command in enable mode:

 ip device tracking interface Fa0/0

ip device tracking interface Fa0/1