MTU, or Maximum Transmission Unit, is the largest possible Ethernet frame a device can forward
IEEE 802.3 standard
Min Ethernet frame size = 64 bytes (B).
Max Ethernet frame size = 1518 B.
Updated to 1522 B for VLAN tagging.
Jumbo frames
Payload greater than 1500 B.
For use on local networks.
Can be as large as 9000 B.
Ports have to be at least 1 Gb/s.
Baby Jumbo frames
Slightly larger than 1500 B payload.
Super Jumbo frames
Payload greater than 9000 B.
MTU Configuration
Configure on a Cisco WS-3750X-48P.
core-switch(config)#system mtu ?
<1500-1998> MTU size in bytes
jumbo Set Jumbo MTU value for GigabitEthernet or TenGigabitEthernet interfaces
routing Set the Routing MTU for the system
Configure on a Cisco 9300-24UX.
sw-27(config)#system mtu ?
<1500-9198> MTU size in bytes