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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-06
Chapter 9 Configuring Interfaces Configuring the System MTU
Note If Layer 2 Gigabit Ethernet interfaces are configured to accept frames greater than the 10/100 interfaces,
jumbo frames received on a Layer 2 Gigabit Ethernet interface and sent on a Layer 2 10/100 interface
are dropped.
Beginning in privileged EXEC mode, follow these steps to change the MTU size for all 10/100 or Gigabit
Ethernet interfaces:
If you enter a value that is outside the allowed range for the specific type of interface, the value is not
accepted.
Once the switch reloads, you can verify your settings by entering the show system mtu privileged EXEC
command.
This example shows how to set the maximum packet size for a Gigabit Ethernet port to 1800 bytes:
Switch(config)# system mtu jumbo 1800
Switch(config)# exit
Switch# reload
This example shows the response when you try to set Gigabit Ethernet interfaces to an out-of-range
number:
Switch(config)# system mtu jumbo 25000
^
% Invalid input detected at '^' marker.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 system mtu bytes (Optional) Change the MTU size for all interfaces on
the switch that are operating at 10 or 100 Mbps. The
range is 1500 to 1998 bytes; the default is 1500 bytes.
Step 3 system mtu jumbo bytes (Optional) Change the MTU size for all Gigabit
Ethernet interfaces on the switch. The range is 1500 to
9000 bytes; the default is 1500 bytes.
Step 4 system mtu routing bytes (Optional) Change the system MTU for routed ports.
The range is 1500 to the system MTU value, the
maximum MTU that can be routed for all ports.
Although larger packets can be accepted, they cannot be
routed.
Step 5 end Return to privileged EXEC mode.
Step 6 copy running-config startup-config Save your entries in the configuration file.
Step 7 reload Reload the operating system.