The original IEEE 802.3 specifications defined a valid Ethernet frame size from 64 to 1,518 bytes. Considering that the standard Ethernet header is 18 bytes in length, then the payload for a standard frame ranges in size from 46 to 1,500 bytes. This is the MTU.

However, since the original Ethernet specification was defined, different IEEE standards have been developed that support additional, expanded frame types listed here as follows:

• VLAN tagging (802.1Q): This is with an additional 4 bytes in the Ethernet header.
• Provider Bridge (802.1ad): This is with an additional 8 bytes to the original frame to support service and customer tagging.
• FCoE frames: These have an MTU of 2,500 bytes.
• Multiprotocol Label Switching (MPLS): This increases the maximum Ethernet frame size to 1,518 bytes + (n * 4 bytes), where n is the number of stacked labels.
• VXLAN: This adds another 50 bytes.
• Jumbo frames: These are Ethernet frames with more than 1,500 bytes of payload, typically around 9,000 bytes. They are mostly used for IP-based storage traffic.

Which is the recommended MTU? If you plan to use jumbo frames for iSCSI or NFS traffic, there is a specific KB 1007654—iSCSI and Jumbo Frames configuration on VMware ESXi/ESX at https://kb.vmware.com/kb/100765. For VXLAN traffic, their recommended MTU is 1,600.