System Mtu - Cisco catalyst 3750 Command Reference Manual

system mtu

system mtu
Use the system mtu global configuration command to set the maximum packet size or maximum
transmission unit (MTU) size for Gigabit Ethernet ports, for routed ports, or for Fast Ethernet (10/100)
ports. Use the no form of this command to restore the global MTU value to its default value.
Syntax Description
bytes
jumbo bytes
routing bytes
Defaults
The default MTU size for all ports is 1500 bytes.However, if you configure a different value for the
system MTU, that configured value becomes the default MTU size for routed ports when it is applied
following a switch reset.
Command Modes Global configuration
Command History Release
12.1(11)AX
12.2(25)SEC
12.2(25)SED
Usage Guidelines
When you use this command to change the system MTU or jumbo MTU size, you must reset the switch
before the new configuration takes effect.The system mtu routing command does not require a switch
reset to take effect.
The system MTU setting is saved in the switch environmental variable in NVRAM and becomes
effective when the switch reloads. Unlike the system MTU routing configuration, the MTU settings you
enter with the system mtu and system mtu jumbo commands are not saved in the switch IOS
configuration file, even if you enter the copy running-config startup-config privileged EXEC
Catalyst 3750 Switch Command Reference
2-868
system mtu {bytes | jumbo bytes | routing bytes}
no system mtu
Set the system MTU for ports that are set to 10 or 100 Mb/s. The range
is 1500 to 1998 bytes. This is the maximum MTU received at 10/100-Mb/s
Ethernet switch ports.
Set the system jumbo MTU for Gigabit Ethernet ports operating at 1000
Mb/s or greater. The range is 1500 to 9000 bytes. This is the maximum MTU
received at the physical port for Gigabit Ethernet ports.
Set the maximum MTU for routed packets. You can also set the maximum
MTU to be advertised by the routing protocols that support the configured
MTU size. The range is 1500 bytes to the system MTU value. The system
routing MTU is the maximum MTU for routed packets and is also the
maximum MTU that the switch advertises in routing updates for protocols
such as OSPF.
Modification
This command was introduced.
The bytes range is now 1500 to 1998.
The routing bytes keywords were added.
Chapter 2 Catalyst 3750 Switch Cisco IOS Commands
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