This document provides the minimum commands needed to enable an LAG and some frequent questions:

When configuring a Layer 2 , (trunk) port LAG is needed. To provide Layer 2 connectivity between vlans

Minimum configuration/ Configuring a LAG for QFX/EX devices ,

(the ports will depend in what is required for the design , it could be any for example 10g or 40g , 25g , 1g ) in this case we will use 10g ports xe-0/0/0 and xe-0/0/1, which will form a 20g logical interface.

set interfaces xe-0/0/0 ether-options 802.3ad ae0

set interfaces xe-0/0/1 ether-options 802.3ad ae0

set interfaces ae0 unit 0 family ethernet-switching interface-mode (this could be trunk or list all vlans or only the vlans per clients design )

set interfaces ae0 aggregated-ether-options lacp active <<<<<< this must match accordingly in the other end , also is optional.

set chassis aggregated-devices ethernet device count 5 (this number depends design needs)

FAQ:

Q/ Can the link carry traffic if one of the child interfaces are down down?

A/ Aggregating multiple links between physical interfaces creates a single logical point-to-point trunk link or a LAG. The LAG balances traffic across the member links within an aggregated Ethernet bundle and effectively increases the uplink bandwidth. Another advantage of link aggregation is increased availability, because the LAG is composed of multiple member links. If one member link fails, the LAG continues to carry traffic over the remaining links.

Q/ Can I configure LACP without active?

A/ You need to configure at least one side as active, to have the interface start sending LACP messages.

When LACP is enabled, one side must be set as active in order for the bundled link to be up.