Reference Guide

668 | IPv4 Routing
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e
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.
Syntax
ip mtu value
To return to the default IP MTU value, enter
no ip mtu.
Parameters
Defaults
1500 bytes
Command Modes
INTERFACE (Gigabit Ethernet and 10 Gigabit Ethernet interfaces)
Command
History
Usage
Information
When you enter no mtu command, FTOS reduces the ip mtu value to 1536 bytes. To return
the IP MTU value to the default, enter
no ip mtu.
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 (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.
Port Channels:
All members must have the same link MTU value and the same IP MTU value.
• The Port Channel link MTU and IP MTU must be less than or equal to the link
MTU and IP MTU values configured on the channel members.
Example: if the members have a link MTU of 2100 and an IP MTU 2000, the Port Channel’s
MTU values cannot be higher than 2100 for link MTU or 2000 bytes for IP MTU.
VLANs:
• All members of a VLAN must have same IP MTU value.
• Members can have different Link MTU values. Tagged members must have a
link MTU 4 bytes higher than untagged members to account for the packet tag.
• The VLAN link MTU and IP MTU must be less than or equal to the link MTU
and IP MTU values configured on the VLAN members.
value Enter the maximum MTU size if the IP packet is fragmented.
Default: 1500 bytes
Range: 576 to 9234
Version 8.3.7.0 Introduced on S4810
Version 8.1.1.0 Introduced on E-Series ExaScale
pre-Version 6.1.1.0 Introduced for E-Series