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Configuring the System MTU
Beginning in privileged EXEC mode, follow these steps to add a description for an interface:
Command
Step 1
configure terminal
Step 2
interface interface-id
Step 3
description string
Step 4
end
Step 5
show interfaces interface-id description
or
show running-config
Step 6
copy running-config startup-config
Use the no description interface configuration command to delete the description.
This example shows how to add a description on a port and how to verify the description:
Switch# config terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface gigabitethernet0/2
Switch(config-if)# description Connects to Marketing
Switch(config-if)# end
Switch# show interfaces gigabitethernet0/2 description
Interface Status
Gi0/2
Configuring the System MTU
The default maximum transmission unit (MTU) size for frames received and transmitted on all interfaces
on the switch 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 jumbo mtu command. If you do not configure the system mtu jumbo command, the setting
of the system mtu command applies to all Gigabit Ethernet interfaces.
You cannot set the MTU size for an individual interface; you set it for all 10/100 or all Gigabit Ethernet
interfaces on the switch. When you change the system or jumbo MTU size, you must reset the switch
before the new configuration takes effect.
Frames sizes that can be received by the switch CPU are limited to 1998 bytes, no matter what value was
entered with the system mtu or system mtu jumbo commands. Although frames that are forwarded are
typically not received by the CPU, in some cases packets are sent to the CPU, such as traffic sent to
control traffic, SNMP, or Telnet.
If Gigabit Ethernet interfaces are configured to accept frames greater than the 10/100 interfaces, jumbo
Note
frames received on a Gigabit Ethernet interface and sent on a 10/100 interface are dropped.
Catalyst 2928 Switch Software Configuration Guide
12-26
Purpose
Enter global configuration mode.
Specify the interface for which you are adding a description, and enter
interface configuration mode.
Add a description (up to 240 characters) for an interface.
Return to privileged EXEC mode.
Verify your entry.
(Optional) Save your entries in the configuration file.
Protocol Description
admin down
down
Chapter 12
Connects to Marketing
Configuring Interface Characteristics
OL-23389-01
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Troubleshooting
