What are two available modes when using LACP with an aggregated Ethernet bundle?

On Junos devices used in data centers, an aggregated Ethernet bundle can run either static bundling or dynamic bundling using LACP. When LACP is used, Junos supports two negotiation modes: active and passive. These modes control whether the device initiates LACP negotiation by transmitting LACP Data Units or whether it waits to respond to LACP Data Units sent by its peer. In active mode, the system periodically sends LACP control frames to begin and maintain the negotiation. In passive mode, the system does not initiate negotiation but will respond if it receives LACP control frames from the neighbor.

From an operational perspective, active is typically recommended on at least one side of the link so the bundle reliably forms even if the peer is configured to be passive. If both ends are passive, each side waits for the other to start, and the aggregated link might not come up as expected. This is a common cause of down or partially formed bundles in leaf spine uplinks and server dual-homing scenarios.

Options aggressive and mixed are not Junos LACP modes for aggregated Ethernet. In Junos, you configure LACP under the aggregated-ether-options hierarchy and select active or passive behavior, along with optional timing such as periodic fast for quicker detection.