Command Line Interface Guide

Ethernet Configuration Commands 421
Syntax
mtu bytes
no mtu
• bytes — Number of bytes (Range: 1518-9216)
Default Configuration
The default number of bytes is 1518 (1522 bytes of VLAN-tagged frames).
Command Mode
Interface Configuration (Ethernet, Port-channel) mode
User Guidelines
Because the switch does not fragment frames, received frames that are larger
than the MTU setting are dropped. Packets originated by the CPU are
fragmented on transmission if the link MTU is smaller than the IP MTU.
Setting the MTU less than the IPv4 MTU causes CPU-generated IPv4
packets to be fragmented. Setting the MTU less than the IPv6 MTU causes
CPU-generated IPv6 packets to be dropped. Setting the MTU also
automatically adjusts the IPv4 MTU. Port-channel and interface MTU
settings are configured and maintained independently. Setting the MTU on a
port-channel adjusts the operational MTU of an interface when the interface
is a member of a LAG. The operational MTU is reset back to the interface
MTU setting when the interface leaves the LAG.
Use the show interfaces mtu command to show the interface MTU.
Example
The following example of the mtu command increases maximum packet size
to 9216 bytes.
console(config-if-1/0/5)#mtu 9216
2CSPC4.X8100-SWUM100.book Page 421 Wednesday, August 29, 2012 6:23 PM