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10-23
Cisco Catalyst Switch Module 3110 and 3012 for IBM BladeCenter Software Configuration Guide
OL-12189-01
Chapter 10 Configuring Interface Characteristics
Configuring the System MTU
The upper limit of the system routing MTU value is based on the switch or switch stack configuration
and refers to either the currently applied system MTU or the system jumbo MTU value. For more
information about setting the MTU sizes, see the system mtu global configuration command in the
command reference for this release.
Beginning in privileged EXEC mode, follow these steps to change the MTU size for switched and routed
packets:
If you enter a value that is outside the allowed range for the specific type of interface, the value is not
accepted.
This example shows how to set the maximum packet size for a Gigabit Ethernet port to 7500 bytes:
Switch(config)# system jumbo mtu 7500
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 jumbo bytes (Optional) Change the MTU size for all Gigabit
Ethernet and 10-Gigabit Ethernet interfaces on the
switch or the switch stack. The range is from 1500 to
9198 bytes.
Step 3
system mtu routing bytes (Optional) Change the system MTU for routed ports.
You can also set the maximum MTU to be advertised by
the routing protocols that support the configured MTU
size. 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.
The range is from 1500 to the system jumbo MTU value
(in bytes).
Step 4
system mtu bytes (Optional) Change the MTU size for all interfaces.
Note The range is 1500 to 1998 bytes; the default is
1500 bytes.
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.
Step 8
show system mtu Verify your settings.