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When configuring the system MTU values, follow these guidelines:
The device does not support the MTU on a per-interface basis.
If you enter the system mtu bytes command in global configuration mode, the command affects all the switched and routed ports on the switch.
The default maximum transmission unit (MTU) size for payload received in Ethernet frame and sent on all device interfaces is 1500 bytes.
The upper limit of the IP or IPv6 MTU value is based on the switch or switch stack configuration and refers to the currently applied system MTU value. For more information about setting the MTU sizes, see the system mtu global configuration command in the command reference for this release.
Follow these steps to change the MTU size for switched packets:
| 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. |
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
| 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
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
Device# configure terminal
Device(config)# system mtu 1600
Device(config)# exit
| MIB | MIBs Link |
|---|---|
|
All the supported MIBs for this release. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
| Description | Link |
|---|---|
|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
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 Fuji 16.9.2 |
System MTU |
System MTU defines the maximum transmission unit size for frames transmitted on all interfaces of a switch. |
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.
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