ip mtu

Syntax

ip mtu <VALUE>

Description

This command sets the MTU (maximum transmission unit) for an IP interface. This defines the largest IP packet that can be sent or received by the interface. The MTU has to account for 28 bytes of IP layer overhead, plus a GRE header (when defining a GRE tunnel). It must be larger than the MTU of the interface that the tunnel is using. Packets larger than the MTU are dropped.

The no form of this command sets the MTU to the default value of 1500 bytes.

Command context

config-gre-if

config-ip-if

Parameters

<VALUE>

Specifies the MTU in bytes. Range: 1280 to 9,192 bytes.

Authority

Administrators

Examples

Sets the MTU on GRE interface 33 to 1300 bytes.

switch(config)# interface tunnel 33 mode gre ipv4
switch(config-gre-if)# mtu 1300

Sets the MTU on GRE interface 33 to the default value.

switch(config)# interface tunnel 33 mode gre ipv4
switch(config-gre-if)# ip mtu

Sets the MTU on IPv6 in IPv4 tunnel 27 to 1000 bytes.

switch(config)# interface tunnel 27 mode ip 6in4
switch(config-ip-if)# mtu 1000

Sets the MTU onIPv6 in IPv4 tunnel 27 to the default value.

switch(config)# interface tunnel 27 mode ip 6in4
switch(config-ip-if)# ip mtu