Reference Guide

Command History
Version 8.3.11.1 Introduced on the Z9000.
Version 8.3.7.0 Introduced on the S4810.
Version 8.1.1.0 Introduced on the E-Series ExaScale.
Version 7.6.1.0 Introduced on the S-Series.
Version 7.5.1.0 Introduced on the C-Series.
pre-Version
6.1.1.0
Introduced for the E-Series.
Usage
Information
To avoid denial of service (DOS) attacks, keep the number of fragments allowed for re-
assembly low.
ip mtu
Set the IP MTU (frame size) of the packet transmitted by the RPM for the line card interface. If the packet must be
fragmented, FTOS sets the size of the fragmented packets to the size specified in this command.
E-Series, S4810
Syntax
ip mtu value
To return to the default IP MTU value, use the no ip mtu command.
Parameters
value Enter the maximum MTU size if the IP packet is fragmented. The
range is 576 to 9234. The default is 1500 bytes.
Defaults 1500 bytes
Command Modes INTERFACE (Gigabit Ethernet and 10 Gigabit Ethernet interfaces)
Command History
Version 8.3.7.0 Introduced on the S4810.
Version 8.1.1.0 Introduced on the E-Series ExaScale.
pre-Version
6.1.1.0
Introduced on the E-Series.
Usage
Information
When you enter the no mtu command, FTOS reduces the ip mtu value to 1536 bytes. To return
the IP MTU value to the default, use the no ip mtu command.
You must compensate for Layer 2 header when configuring link MTU on an Ethernet interface
or FTOS may not fragment packets. If the packet includes a Layer 2 header, the difference
between the link MTU and IP MTU (the ip mtu command) must be enough bytes to include
for the Layer 2 header.
Link MTU and IP MTU considerations for Port Channels and VLANs are as follows
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