For example, I will configure the LAG on the Juniper QFX5100, by which I will connect the Juniper MX204.
Specify how many aggregations will be configured on the switch (in my case one, it affects the allocated resources of the device, then you can change it without rebooting):
set chassis aggregated-devices ethernet device-count 1
Specify the minimum number of links for which the ae0 interface should work:
set interfaces ae0 aggregated-ether-options minimum-links 1
Specify the speed:
set interfaces ae0 aggregated-ether-options link-speed 40g
Specify the required VLANs:
set interfaces ae0 unit 0 family ethernet-switching vlan members [ core users ]
Let’s configure the ports that will participate in the aggregation:
set interfaces et-0/0/22 ether-options 802.3ad ae0
set interfaces et-0/0/23 ether-options 802.3ad ae0
set interfaces et-0/0/22 gigether-options no-flow-control
set interfaces et-0/0/23 gigether-options no-flow-control
Specify the trunk mode in one of the commands:
set interfaces ae0 unit 0 family ethernet-switching interface-mode trunk
set interfaces ae0 unit 0 family ethernet-switching port-mode trunk
Additional settings:
set interfaces ae0 aggregated-ether-options lacp active
set interfaces ae0 aggregated-ether-options lacp periodic fast
If there are old settings on the ports that will participate in the aggregation, then we will look at them and delete them:
edit interfaces et-0/0/22
show
delete unit 0
delete vlan-tagging
edit interfaces et-0/0/23
show
...
exit
Let’s apply the configuration:
commit check
commit
Let’s check the ae0 interface:
run show interfaces ae0
run show interfaces ae0 terse
See also my article:
Interface Aggregation (LAG) on Juniper MX