Enabling Jumbo Frames on RHEL7 with nmcli

Use the NetworkManager command-line tool to see your connections:

# nmcli connection show --active
NAME UUID TYPE DEVICE
em1 7bb105a5-f663-4e5b-a8aa-fdeb2a16e1a0 802-3-ethernet em1


View the attributes of a single connection:

# nmcli connection show em1
...
802-3-ethernet.mtu: auto


Change the MTU to your new value (in this example, 9000):

# nmcli connection modify em1 802-3-ethernet.mtu 9000


Check for the change:

# nmcli connection show em1
...
802-3-ethernet.mtu: 9000