Today I had a customer ask me so what happens if I select Enable MAC Learning when I create a new logical switch. Well the answer is simple and most likely something you will never need to use. Enabling MAC learning is useful if the virtual workloads have multiple MAC addresses or are using vmnics with trunking.
Enabling MAC Learning builds a VLAN/MAC pair learning table on each vNic. This table is stored as part of the dvfilter data. During vMotion, dvfilter saves and restores the table at the new location. The switch then issues RARPs for all the VLAN/MAC entries in the table.