To provide a redundancy on session (or flow), the data plane software synchronizes its state by sending special payload packets called runtime objects (RTOs) from one node to the other across the fabric data link. By transmitting information about a session between the nodes, RTOs ensure the consistency and stability of sessions if a failover were to occur, and thus they enable the system to continue to process traffic belonging to existing sessions. To ensure that session information is always synchronized between the two nodes, the data plane software gives RTOs transmission priority over transit traffic.
The control plane software, which operates in active/backup mode, is an integral part of JUNOS Software that is active on the primary node of a cluster. It achieves redundancy by communicating state, configuration, and other information to the inactive Routing Engine on the secondary node. If the master Routing Engine fails, the secondary one is ready to assume control.
Below you will see the commands/steps that you can run and follow to request a Data Plane failover (primary -à secondary):
Author: Eric Uwonkunda Ngabonziza