- Configuring Interface Characteristics
- Configuring Auto-MDIX
- Configuring Ethernet Management Port
- Checking Port Status and Connectivity
- Configuring LLDP, LLDP-MED, and Wired Location Service
- Configuring System MTU
- Configuring Per-Port MTU
- Configuring EEE
- Configuring Power over Ethernet
- Configuring 2-event Classification
- Configuring COAP Proxy Server
- Configuring an External USB Bluetooth Dongle
- M2 SATA Module
- Troubleshooting Interface and Hardware Components
Configuring System MTU
Information About the MTU
The default maximum transmission unit (MTU) size for payload received in Ethernet frame and sent on all device interfaces is 1500 bytes.
System MTU Value Application
This table shows how the MTU values are applied.
Configuration |
system mtu command |
---|---|
Standalone switch |
You can enter the system mtu command on a switch and it affects all ports on the switch. The range is from 1500 to 9216 bytes. |
For more information about setting the MTU sizes, see the system mtu global configuration command in the command reference for this release.
Beginning from Cisco IOS XE Amsterdam 17.3.x, the minimum IPv6 system MTU is fixed at 1280 as per RFC 8200.
How to Configure MTU
Configuring the System MTU
Follow these steps to change the MTU size for switched packets:
Procedure
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode.
|
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
system mtu bytes Example:
|
(Optional) Changes the MTU size for all interfaces. |
Step 4 |
end Example:
|
Returns to privileged EXEC mode. |
Step 5 |
copy running-config startup-config Example:
|
Saves your entries in the configuration file. |
Step 6 |
show system mtu Example:
|
Verifies your settings. |
Configuring Protocol-Specific MTU
To override system MTU values on routed interfaces, configure protocol-specific MTU under each routed interface. To change the MTU size for routed ports, perform this procedure
Procedure
Command or Action | Purpose | |
---|---|---|
Step 1 |
configure terminal Example:
|
Enters global configuration mode. |
Step 2 |
interface interface Example:
|
Enters interface configuration mode. |
Step 3 |
ip mtu bytes Example:
|
Changes the IPv4 MTU size |
Step 4 |
ipv6 mtu bytes Example:
|
(Optional) Changes the IPv6 MTU size. |
Step 5 |
end Example:
|
Returns to privileged EXEC mode. |
Step 6 |
copy running-config startup-config Example:
|
Saves your entries in the configuration file. |
Step 7 |
show system mtu Example:
|
Verifies your settings. |
Configuration Examples for System MTU
Example: Configuring Protocol-Specific MTU
Device# configure terminal
Device(config)# interface gigabitethernet 0/1
Device(config-if)# ip mtu 900
Device(config-if)# ipv6 mtu 1286
Device(config-if)# end
Example: Configuring the System MTU
Device# configure terminal
Device(config)# system mtu 1600
Device(config)# exit
Additional References for System MTU
Related Documents
Related Topic | Document Title |
---|---|
For complete syntax and usage information for the commands used in this chapter. |
See the Interface and Hardware Commands section in the Command Reference (Catalyst 9400 Series Switches) |
Standards and RFCs
Standard/RFC | Title |
---|---|
RFC 8200 |
Internet Protocol, Version 6 (IPv6) Specification |
Feature History for System MTU
This table provides release and related information for features explained in this module.
These features are available on all releases subsequent to the one they were introduced in, unless noted otherwise.
Release |
Feature |
Feature Information |
---|---|---|
Cisco IOS XE Everest 16.6.1 |
System MTU |
System MTU defines the maximum transmission unit size for frames transmitted on all interfaces of a switch. |
Cisco IOS XE Cupertino 17.7.1 |
System MTU |
This feature was implemented on supervisor modules C9400X-SUP-2 and C9400X-SUP-2XL, which were introduced in this release. |
Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.