The fabric (fab) link in a Juniper SRX chassis cluster is a dedicated, high-speed connection responsible for synchronizing real-time objects (RTOs) and forwarding data plane traffic between the two nodes. To ensure optimal performance and low latency for this critical function, the fab link does not support packet fragmentation. The MTU of the physical interfaces used for the fab link must be large enough to handle the largest data packet plus an internal header. Furthermore, the physical interfaces that will serve as the fab link(s) must be explicitly defined in the chassis cluster configuration, binding them to the logical fab0 or fab1 interfaces.

C. The fab link supports traditional interface features.

This is incorrect. The fab link is a special-purpose internal link for cluster synchronization and does not support standard interface features like firewall filters or most Class of Service (CoS) policies.

D. The Junos OS supports only one fab link.

This is incorrect. Junos OS supports configuring up to two fabric links (fab0 and fab1) to provide redundancy and increased bandwidth for the data plane connection between the nodes.

1. Juniper Networks TechLibrary

Chassis Cluster Feature Guide for SRX Series Devices

"Understanding Chassis Cluster Fabric Links". This document states

"The fabric link does not support fragmentation." It also details the purpose of the link

which is distinct from traditional interfaces.

2. Juniper Networks TechLibrary

Junos OS Security Configuration Guide

"Configuring Chassis Cluster Fabric Interfaces (CLI Procedure)". This guide shows the explicit configuration commands required: set chassis cluster fabric-link member-interface

confirming that the physical interface must be specified.

3. Juniper Networks TechLibrary

Chassis Cluster Feature Guide for SRX Series Devices

"Example: Configuring an SRX Series Chassis Cluster". This configuration example explicitly shows the setup for both fab0 and fab1

demonstrating that more than one fab link is supported. For instance

set chassis cluster fabric-link member-interface fab0 member-interface ge-0/0/1 and set chassis cluster fabric-link member-interface fab1 member-interface ge-5/0/1.