MC-LAG: Keep a link up on a multichassis link aggregation group (MC-LAG) when LACP is not configured on one of the MC-LAG peers

Junos OS provides connectivity from provider edge devices to customer edge devices when LACP is not configured on a customer edge device. The customer edge device must have one link connected to the provider edge device, though, and multichassis link aggregation must be configured between the provider edge devices in the MC-LAG. You can configure the force-up feature in Link Aggregation Control Protocol (LACP) on the provider edge device for which you need connectivity. Additionally, only one member interface in the aggregated Ethernet interface can be active, otherwise the provider edge device will receive duplicate packets.