Juniper Exam JN0-335 Topic 3 Question 18 Discussion

The fab interface is a fabric link that connects the two nodes in a chassis cluster. A chassis cluster is a high-availability feature that groups two identical SRX Series devices into a cluster that acts as a single device. The fab interface has two functions:

Real-time objects (RTOs) are exchanged on the fab interface to maintain session synchronization: RTOs are data structures that store information about active sessions, such as source and destination IP addresses, ports, protocols, and security policies. RTOs are exchanged between the nodes on the fab interface to ensure that both nodes have the same session information and can take over the traffic in case of a failover.

In an active/active configuration, inter-chassis transit traffic is sent over the fab interface: In an active/active configuration, both nodes in a cluster can process traffic for different redundancy groups (RGs). RGs are collections of interfaces or services that fail over together from one node to another. If traffic needs to transit from one RG to another RG that is active on a different node, it is sent over the fab interface.