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The default maximum transmission unit (MTU) size for frames received and transmitted on all interfaces is 1500 bytes. You can increase the MTU size for all interfaces operating at 10 or 100 Mb/s by using the system mtu global configuration command. You can increase the MTU size to support jumbo frames on all Gigabit Ethernet interfaces by using the system mtu jumbo global configuration command.
Note | The switch supports jumbo frames at CPU. |
When configuring the system MTU values, follow these guidelines:
The default maximum transmission unit (MTU) size for frames received and transmitted on all interfaces is 1500 bytes. You can increase the MTU size for all interfaces operating at 10 or 100 Mb/s by using the system mtu global configuration command. You can increase the MTU size to support jumbo frames on all Gigabit Ethernet interfaces by using the system mtu jumbo global configuration command.
Gigabit Ethernet ports are not affected by the system mtu command; 10/100 ports are not affected by the system mtu jumbo command. If you do not configure the system mtu jumbo command, the setting of the system mtu command applies to all Gigabit Ethernet interfaces.
Beginning in privileged EXEC mode, follow these steps to change the MTU size for all 10/100 or Gigabit Ethernet interfaces:
1.
configure terminal
2.
system mtu
bytes
3.
system mtu
jumbo
bytes
4.
end
5.
copy
running-config startup-config
6.
reload
7.
show system mtu
This example shows how to set the maximum packet size for a Gigabit Ethernet port to 7500 bytes:
Switch(config)# system mtu 1900 Switch(config)# system mtu jumbo 7500 Switch(config)# exit
If you enter a value that is outside the allowed range for the specific type of interface, the value is not accepted. This example shows the response when you try to set Gigabit Ethernet interfaces to an out-of-range number:
Switch(config)# system mtu jumbo 25000
^
% Invalid input detected at '^' marker.
This is an example of output from the show system mtu command:
Switch# show system mtu
Global Ethernet MTU is 1500 bytes.
Description | Link |
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To help you research and resolve system error messages in this release, use the Error Message Decoder tool. |
https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi |
MIB | MIBs Link |
---|---|
All 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 |
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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. |
Release |
Modification |
---|---|
Cisco IOS 15.0(2)EX
|
This feature was introduced. |