Configuring System MTU

Information About the MTU

The default maximum transmission unit (MTU) size for frames received and transmitted on all interfaces is 1500 bytes.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.

System MTU Guidelines

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 1522 bytes. You can increase the MTU size to support jumbo frames on all Gigabit Ethernet interfaces by using the system mtu jumbo global configuration command.

How to Configure MTU

Configuring the System MTU

Beginning in privileged EXEC mode, follow these steps to change the MTU size for all 10/100 or Gigabit Ethernet interfaces:

SUMMARY STEPS

configure terminal
system mtu bytes
system mtu jumbo
end
copy running-config startup-config
do show system mtu

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure terminal Example: `Device# configure terminal`	Enters global configuration mode.
Step 2	system mtu `bytes` Example: `Device(config)# system mtu 1500`	(Optional) Change the MTU size for all interfaces on the switch stack that are operating at 10 or 100 Mb/s. Enter 1500, 2026 or jumbo to specify the MTU size. The MTU value of jumbo is 10218.
Step 3	system mtu jumbo Example: `Device(config)# system mtu jumbo`	(Optional) Changes the MTU size for all Gigabit Ethernet interfaces on the switch or the switch stack. Enter 1500, 2026 or jumbo to specify the MTU size. The MTU value of jumbo is 10218.
Step 4	end Example: `Device(config)# end`	Returns to privileged EXEC mode.
Step 5	copy running-config startup-config Example: `Device# copy running-config startup-config`	Saves your entries in the configuration file.
Step 6	do show system mtu Example: `Device# do show system mtu`

Configuration Examples for System MTU

This example shows how to set the maximum packet size for a Gigabit Ethernet port to 1500 bytes:


Device(config)# system mtu 1500system mtu 1900

Device(config)# exit

This is an example of output from the show system mtu command:


Device# show system mtu
System MTU size is 1500 bytes.

Additional References for System MTU

MIBs


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: http://www.cisco.com/go/mibs

Technical Assistance


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.	http://www.cisco.com/support

Feature Information for System MTU


Release	Modification
Cisco IOS Release 15.0(2)EXCisco IOS Release 15.2(5)E	This feature was introduced.

Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(7)E (Catalyst 2960-X Switch)

Bias-Free Language

Book Title

Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(7)E (Catalyst 2960-X Switch)

Chapter Title