Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


one-to-one (Aggregated Multiservices)


Hierarchy Level


Configure a single interface to be the preferred one-to-one (1:1) backup for an active aggregated multiservices (AMS) interface. If the active interface fails, the backup interface takes over. A 1:1 (stateful) configuration synchronizes traffic states and data structures between the active and backup PICs. This is required for high availability of IPsec connections. 1:1 configuration is supported only on MS-MPCs but is not currently supported on MX-SPC3s.


The preferred backup must be one of the member interfaces (mams–) that have already been configured at the [edit interfaces interface-name load-balancing-options] hierarchy level.


preferred-backup preferred-backup

Use the specified interface as the preferred backup member interface. The member interface format is mams-a/b/0, where a is the Flexible PIC Concentrator (FPC) slot number and b is the PIC slot number.

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 15.2.