Inter-Chassis Stateful Synchronization Overview
Stateful synchronization replicates the state of long-lived NAT, stateful firewall, and IDS sessions on the master services PIC and sends it to the backup services PIC, which is on a different MX Series chassis. By default, long lived sessions are defined as having been active on the services PIC for at least 180 seconds, though you can configure this to a higher value.
The following restrictions apply:
NAPT44 is the only translation type supported.
Replicating state information for the port block allocation (PBA), endpoint-independent mapping (EIM), or endpoint-independent filters (EIF) features are supported supported for Next Gen Services.
When configuring a service set for NAT, stateful firewall, or IDS that belongs to a stateful synchronization setup, you must use a next-hop service set, and the NAT, stateful firewall, and IDS configurations for the service set must be identical on both MX Series chassis.
Figure 1 shows the stateful synchronization topology.
Interchassis stateful synchronization of the services session state allows uninterrupted services when a switchover occurs from a services PIC on one chassis to a services PIC on another chassis.