ESXi includes an SNMP agent that can send notifications (traps and informs) and receive GET, GETBULK, and GETNEXT requests.
In ESXi 5.1 and later releases, the SNMP agent adds support for version 3 of the SNMP protocol, offering increased security and improved functionality, including the ability to send informs. You can use esxcli commands to enable and configure the SNMP agent. You configure the agent differently depending on whether you want to use SNMP v1/v2c or SNMP v3.
As an alternative to configuring SNMP manually using esxcli commands, you can use host profiles to configure SNMP for an ESXi host. See the vSphere Host Profiles documentation for more information.