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    Chassis Cluster Overview

    Chassis cluster groups a pair of the same kind of vSRX instances into a cluster to provide network node redundancy. The vSRX instances in a chassis cluster must be running the same Junos OS release, and each instance becomes a node in the chassis cluster. You connect the control virtual interfaces on the respective nodes to form a control plane that synchronizes the configuration and Junos OS kernel state on both nodes in the cluster. The control link (a virtual network or vSwitch) facilitates the redundancy of interfaces and services. Similarly, you connect the data plane on the respective nodes over the fabric virtual interfaces to form a unified data plane. The fabric link (a virtual network or vSwitch) allows for the management of cross-node flow processing and for the management of session redundancy.

    The control plane software operates in active/passive mode. When configured as a chassis cluster, one node acts as the primary and the other as the secondary to ensure stateful failover of processes and services in the event of a system or hardware failure on the primary . If the primary fails, the secondary takes over processing of control plane traffic.

    Note: If you configure a chassis cluster across two hosts, disable igmp-snooping on the bridge that each host physical interface belongs to and that the control virtual NICs (vNICs) use. This ensures that the control link heartbeat is received by both nodes in the chassis cluster.

    The chassis cluster data plane operates in active/active mode. In a chassis cluster, the data plane updates session information as traffic traverses either node, and it transmits information between the nodes over the fabric link to guarantee that established sessions are not dropped when a failover occurs. In active/active mode, traffic can enter the cluster on one node and exit from the other node.

    Chassis cluster functionality includes:

    • Resilient system architecture, with a single active control plane for the entire cluster and multiple Packet Forwarding Engines. This architecture presents a single device view of the cluster.
    • Synchronization of configuration and dynamic runtime states between nodes within a cluster.
    • Monitoring of physical interfaces, and failover if the failure parameters cross a configured threshold.
    • Support for generic routing encapsulation (GRE) and IP-over-IP (IP-IP) tunnels used to route encapsulated IPv4 or IPv6 traffic by means of two internal interfaces, gr-0/0/0 and ip-0/0/0, respectively. Junos OS creates these interfaces at system startup and uses these interfaces only for processing GRE and IP-IP tunnels.

    At any given instant, a cluster node can be in one of the following states: hold, primary, secondary-hold, secondary, ineligible, or disabled. Multiple event types, such as interface monitoring, Services Processing Unit (SPU) monitoring, failures, and manual failovers, can trigger a state transition.

    Modified: 2017-05-11