To configure the speed and duplex of an interface on a Juniper device QFX running Junos using the Command Line Interface (CLI), follow these steps:

Log in to the device as a user with administrative privileges.
Enter configuration mode by typing the following command:

SYNTAX:

configure

Specify the interface that you want to configure by typing its name. For example, to configure the speed and duplex of interface ge-0/0/0, enter the following command:

SYNTAX:

set interfaces ge-0/0/0 speed 1000m

To set the duplex, use the following command:

SYNTAX:

set interfaces ge-0/0/0 ether-options no-auto-negotiation

set interfaces ge-0/0/0 ether-options link-mode full-duplex

Note: Replace “ge-0/0/0” with the name of the interface that you want to configure.

Commit the changes by entering the following command:

SYNTAX:

commit

Verify that the configuration has been applied correctly by entering the following command:

SYNTAX:

show interfaces ge-0/0/0

This will display the interface configuration, including the speed and duplex settings that you just configured.You have successfully configured the speed and duplex of an interface on a Juniper device QFX running Junos using the CLI.