Specifications

mtu
MP-360
Cisco IOS Multiprotocol Label Switching Command Reference
January 2010
Usage Guidelines Each interface has a default maximum packet size or MTU size. This number generally defaults to the
largest size possible for that interface type. On serial interfaces, the MTU size varies but cannot be set
to a value less than 64 bytes.
Changing the MTU Size
Changing the MTU size is not supported on a loopback interface.
Changing an MTU size on a Cisco 7500 series router results in the recarving of buffers and resetting of
a
ll interfaces. The following message is displayed:
%RSP-3-Restart:cbus complex
.
You can configure native Gigabit Ethernet ports on the Cisco 7200 series router to a maximum MTU size
of
9216 bytes. The MTU values range from 1500 to 9216 bytes.
Protocol-Specific Versions of the mtu Command
Changing the MTU value with the mtu interface configuration command can affect values for the
protocol-specific versions of the command (the ip mtu command, for example). If the value specified
with the ip mtu interface configuration command is the same as the value specified with the mtu
interface configuration command, and you change the value for the mtu interface configuration
command, the ip mtu v
alue automatically matches the new mtu interface configuration command value.
However, changing the values for the ip mtu c
onfiguration commands has no effect on the value for the
mtu interface configuration command.
ATM and LANE Interfaces
ATM interfaces are not bound by what is configured on the major interface. By default, the MTU on a
subinterface is equal to the default MTU (4490); if a client is configured, the default is 1500. The MTU
can be changed on subinterfaces, but it may result in recarving of buffers to accommodate the new
maximum MTU on the interface.
Cisco 7600 Valid MTU Values
On the Cisco 7600 platform, valid values are from 64 to 9216 for SVI ports; from 1500 to 9170 for the
GE-WAN+ ports; and from 1500 to 9216 for all other ports.
If you enable the jumbo frames, the default is 64 for the SVI ports and 9216 for all the other ports. The
j
umbo frames are disabled by default.
Cisco uBR10012 Universal Broadband Router
When configuring the interface MTU size on a Gigabit Ethernet SPA on a Cisco uBR10012 router,
consider the following guidelines:
• The default interface MTU size accommodates a 1500-byte packet, plus 22 additional bytes to cover
the following additional overhead:
– Layer 2 header—14 bytes
12.2(33)SCB This command was integrated into Cisco IOS Release 12.2(33)SCB.
Cisco IOS XE
Re
lease 2.4
This command was modified. Support for the xconnect subinterface
configuration mode was added for this command. The command was
integrated into Cisco IOS XE Release 2.4.
Release Modification