Cisco Catalyst 3550

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Catalyst 3550 Multilayer Switch Command Reference
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Chapter 2 Catalyst 3550 Switch Cisco IOS Commands
system mtu
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 return to the default
setting.
system mtu bytes
no system mtu
Syntax Description
Defaults The default MTU size is 1500 bytes.
Command Modes Global configuration
Command History
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.
bytes Packet size in bytes. The range is 1500 to 2000 bytes for Gigabit Ethernet
switches and 1500 to 1546 bytes for Fast Ethernet switches.
Release Modification
12.1(4)EA1 This command was introduced.