• MTU, or Maximum Transmission Unit, is the largest possible Ethernet frame a device can forward

• 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.

• 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

CCIE-EI v1.1