By default, ESXi provides an extensible multipathing module called the Native Multipathing Plug-In (NMP).
Generally, the VMware NMP supports all storage arrays listed on the VMware storage HCL and provides a default path selection algorithm based on the array type. The NMP associates a set of physical paths with a specific storage device, or LUN. The specific details of handling path failover for a given storage array are delegated to a Storage Array Type Plug-In (SATP). The specific details for determining which physical path is used to issue an I/O request to a storage device are handled by a Path Selection Plug-In (PSP). SATPs and PSPs are sub plug-ins within the NMP module.
With ESXi, the appropriate SATP for an array you use will be installed automatically. You do not need to obtain or download any SATPs.