System Mtu - Cisco Catalyst 3550 Command Reference Manual

Chapter 2 Cisco IOS Commands

system mtu

Use the system mtu global configuration command to set the maximum packet size or maximum
transmission unit (MTU) size for the switch. Use the no form of this command to restore the global MTU
value to its original default value.
Syntax Description
bytes
Defaults
The default MTU size is 1500 bytes.
Command Modes
Global configuration
Command History Release
12.1(4)EA1
Usage Guidelines
When you use this command to change the MTU size, you must reset the switch before the new
configuration takes effect.
If you enter a value that is outside the range for the specific type of switch, the value is not accepted.
Note The switch does not support setting the MTU on a per-interface basis.
The size of frames that can be received by the switch CPU is limited to 1500 bytes, no matter what value
was entered with the system mtu command. Although frames that are forwarded or routed typically are
not received by the CPU, in some cases packets are sent to the CPU, such as traffic sent to control traffic,
SNMP, Telnet, or routing protocols.
Examples
This example shows how to set the maximum packet size for a Gigabit Ethernet switch to 1580 bytes:
Switch(config)# system mtu 1580
Switch(config)# exit
Switch# reload
This example shows the response when you try to set a Fast Ethernet switch to an out-of-range number:
Switch(config)# system mtu 1580
% Invalid input detected at '^' marker.
You can verify your settings by entering the show system mtu privileged EXEC command.
78-11195-09
system mtu bytes
no system mtu
Packet size in bytes. The range is from 1500 to 2000 bytes for Gigabit
Ethernet switches and from 1500 to 1546 bytes for Fast Ethernet switches.
Modification
This command was first introduced.
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Catalyst 3550 Multilayer Switch Command Reference
system mtu
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