Administrator Guide

To return to the default MTU value, use the no mtu command.
Parameters
value Enter a maximum frame size in bytes. The range is from 594 to 9216. The default is
1554.
Defaults 1554
Command Modes INTERFACE
Command
History
This guide is platform-specific. For command information about other platforms, see the relevant Dell
Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version Description
9.10(0.0) Reduced the maximum size of the maximum transmission unit (MTU) to 9216
bytes.
9.9(0.0) Introduced on the C9010.
9.2(1.0) Introduced on the Z9500.
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.3.7.0 Introduced on the S4810.
8.1.1.0 Introduced on the E-Series ExaScale.
7.5.1.0 Introduced on the C-Series.
6.2.1.0 Introduced on the E-Series.
Usage
Information
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 the Layer 2 header.
When you enter the no mtu command, the system reduces the IP MTU value to 1536 bytes.
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. For 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. For example, the VLAN contains tagged members with Link MTU
of 1522 and IP MTU of 1500 and untagged members with Link MTU of 1518 and IP MTU of 1500. The
VLAN’s Link MTU cannot be higher than 1518 bytes and its IP MTU cannot be higher than 1500 bytes.
The following shows the difference between Link MTU and IP MTU.
Layer 2
Overhead
Link MTU and IP MTU Delta
Ethernet
(untagged)
18 bytes
VLAN Tag 22 bytes
734 Interfaces