Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

 
 

Monitor Chassis Cluster Interfaces

Learn interface monitoring, which tracks the operational state of an interface by determining whether it is up or down. If one or more monitored interfaces fail, the associated redundancy group fails over to the other node in the cluster.

Chassis Cluster Redundancy Group Interface Monitoring

For a redundancy group to automatically failover to the peer node, its interfaces must be configured for monitoring. When you configure a redundancy group, you can specify a set of interfaces whose operational status (up or down) is monitored to determine the health of the group. A monitored interface can be a child interface of any redundant Ethernet interface.associated with the redundancy group. Each monitored interface is assigned a weight.

Every redundancy group has a threshold tolerance value, which is set to 255 by default. When a monitored interface becomes unavailable, its configured weight is subtracted from the redundancy group's threshold. When the threshold reaches 0, the redundancy group fails over to the other node. For example, if redundancy group 1 is primary on node 0, and its threshold reaches 0, redundancy group 1 fails over and becomes primary on node 1. At that point, all child interfaces of the redundant Ethernet interfaces associated with redundancy group 1 on node 1 begin forwarding traffic.

You can verify the interface weight by running the following operational mode commands:

  • show chassis cluster information

  • show chassis cluster interfaces

We do not recommend configuring data plane features, such as interface monitoring and IP monitoring, on redundancy group 0 (RG0) for Firewalls in a chassis cluster.

Use redundancy group 0 (RG0) manual failovers with caution. An RG0 failover results in a a Routing Engine (RE) failover, during which all processes running on the current primary node are terminated and then restarted on the new primary Routing Engine (RE). This process can cause loss of state, such as routing information, and may temporarily degrade system performance due to increased system churn.

A redundancy group failover occurs when the cumulative weight of the redundancy group's monitored interfaces reduces its threshold value to 0. If the monitored interfaces of a redundancy group on both nodes reach their thresholds at the same time, the redundancy group becomes primary on the node with the lower node ID. In a two-node cluster, this is node 0.

  • To reduce the frequency of failovers caused by interface monitoring failures, use the hold-down-interval statement.

  • If a failover occurs for redundancy group 0 (RG0), interface monitoring on the RG0 secondary node is disabled for 30 seconds. This behavior prevents other redundancy groups from failing over simultaneously with the RG0 failover.

Benefits of Monitoring Chassis Cluster Redundancy Group Interfaces

  • Determines the operational status of a specific interface in a chassis cluster as monitored by a given redundancy group.

  • Enables automatic failover of the interface to the peer node if the interface goes down.

Example: Configure Chassis Cluster Redundancy Group Interface Monitoring

This example shows how to configure an interface to be monitored by a specific redundancy group for automatic failover to the peer node. It also shows how to assign a weight to the monitored interface and how to verify the remaining threshold by configuring two interfaces on each node and associating them with redundancy groups.

Requirements

Before you begin, create a redundancy group. See Example: Configuring Chassis Cluster Redundancy Groups.

Overview

To determine the remaining redundancy group threshold after a monitored interface goes down, you can configure the system to monitor the health of the interfaces associated with a redundancy group. When you assign a weight to a monitored interface, the system continuously checks the interface's availability. If a physical interface fails, its configured weight is subtracted from the threshold of the associated redundancy group .

Each redundancy group has a default threshold value of 255. When the threshold is reduced to 0, a failover is triggered, even if the redundancy group is configured for manual failover and the preempt option is not enabled.

In this example, you verify the remaining threshold behavior by configuring two interfaces on each node and associating them to redundancy group 1 (RG1), each with different weights. The interfaces on node 0 are assigned weights of 130 and 140, while the interfaces on node 1 are assigned weights of 150 and 120. Additionally, one interface from each node is configured and associated with redundancy group 2 (RG2), using the default interface weight of 255.

Figure 1 illustrates the network topology used in this example.

Topology

Figure 1: SRX Series Chassis Cluster Interface Monitoring Topology Network diagram of two SRX Series devices in high availability cluster, showing Node 0 and Node 1 connected by fabric and control links, with host devices H0 and H1.

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the edit hierarchy level, and then enter commit from configuration mode.

Procedure

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For instructions on how to do that, see Using the CLI Editor in Configuration Mode in the Junos OS CLI User Guide.

To configure chassis cluster interface monitoring:

  1. Specify the number of redundant Ethernet interfaces.

  2. Set up redundancy group 0 for the Routing Engine failover properties, and set up RG1 and RG2 (all interfaces are in one redundancy group in this example) to define the failover properties for the redundant Ethernet interfaces.

  3. Set up interface monitoring to monitor the health of the interfaces and trigger redundancy group failover.

    We do not recommend enabling interface monitoring for RG0, because interface flaps can cause the control plane to switch between nodes.

    Interface failover occurs only when the redundancy group's threshold reaches zero.

  4. Set up the redundant Ethernet (reth) interfaces and assign them to a zone.

Results

From configuration mode, confirm your configuration by entering the show chassis and show interfaces commands. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.

If you are done configuring the device, enter commit from configuration mode.

Verification

The following sections guide you through verifying and, when necessary , troubleshooting interface status. The process shows how to check the status of each interface in a redundancy group, verify the status after interfaces are disabled, and review detailed information for each interface until all interfaces in the redundancy group have been examined.

Verify Chassis Cluster Status

Purpose

Verify the chassis cluster status, failover status, and redundancy group information.

Action

From operational mode, enter the show chassis cluster status command.

Meaning

Use the show chassis cluster status command to confirm that devices in the chassis cluster are communicating properly, with one device functioning as the primary node and the other as the secondary node.

Verify Chassis Cluster Interfaces

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster interfaces command.

Meaning

The sample output confirms that monitoring interfaces are up and that the weight of each interface being monitored is displayed correctly as configured. These values do not change if the interface goes up or down. The weights only change for the redundant group and can be viewed when you use the show chassis cluster information command.

Verify Chassis Cluster Information

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster information command.

Meaning

The sample output confirms that node 0 and node 1 are healthy, and the green LED on the device indicates that there are no failures. Also, the default weight of the redundancy group (255) is displayed. The default weight is deducted whenever an interface mapped to the corresponding redundancy group goes down.

Refer to the following verification sections to observe how the redundancy group value changes when a monitored interface goes down or comes back up.

Verifyi Interface ge-0/0/1 Status After Disabling Interface ge-0/0/1 of RG1 in Node 0 with a Weight of 130

Purpose

Verify that the interface ge-0/0/1 is disabled on node 0.

Action

From configuration mode, enter the set interface ge-0/0/1 disable command.

Meaning

The sample output confirms that interface ge-0/0/1 is disabled.

Verify Chassis Cluster Status After Disabling Interface ge-0/0/1 of RG1 in Node 0 with a Weight of 130

Purpose

Verify the chassis cluster status, failover status, and redundancy group information.

Action

From operational mode, enter the show chassis cluster status command.

Meaning

Use the show chassis cluster status command to confirm that devices in the chassis cluster are communicating properly, with one device functioning as the primary node and the other as the secondary node.

Verify Chassis Cluster Interfaces After Disabling Interface ge-0/0/1 of RG1 in Node 0 with a Weight of 130

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster interfaces command.

Meaning

The sample output confirms that monitoring interface ge-0/0/1 is down.

Verify Chassis Cluster Information After Disabling Interface ge-0/0/1 of RG1 in Node 0 with a Weight of 130

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster information command.

Meaning

The sample output confirms that in node 0, the RG1 weight is reduced to 125 (that is, 255 minus 130) because monitoring interface ge-0/0/1 (weight of 130) went down. The monitoring status is unhealthy, the device LED is amber, and the interface status of ge-0/0/1 is down.

If interface ge-0/0/1 is brought back up, the weight of RG1 in node 0 becomes 255. Conversely, if interface ge-0/0/2 is also disabled, the weight of RG1 in node 0 becomes 0 or less (in this example, 125 minus 140 = -15) and triggers failover, as indicated in the next verification section.

Verify Interface ge-0/0/2 Is Disabled

Purpose

Verify that interface ge-0/0/2 is disabled on node 0.

Action

From configuration mode, enter the set interface ge-0/0/2 disable command.

Meaning

The sample output confirms that interface ge-0/0/2 is disabled.

Verify Chassis Cluster Status After Disabling Interface ge-0/0/2

Purpose

Verify the chassis cluster status, failover status, and redundancy group information.

Action

From operational mode, enter the show chassis cluster status command.

Meaning

Use the show chassis cluster status command to confirm that devices in the chassis cluster are communicating properly, with one device functioning as the primary node and the other as the secondary node. On RG1, you see interface failure, because both interfaces mapped to RG1 on node 0 failed during interface monitoring.

Verify Chassis Cluster Interfaces After Disabling Interface ge-0/0/2

Purpose

Verify information about chassis cluster interfaces.

Action

From operational mode, enter the show chassis cluster interfaces command.

Meaning

The sample output confirms that monitoring interfaces ge-0/0/1 and ge-0/0/2 are down.

Verify Chassis Cluster Information After Disabling Interface ge-0/0/2

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster information command.

Meaning

The sample output confirms that in node 0, monitoring interfaces ge-0/0/1 and ge-0/0/2 are down. The weight of RG1 on node 0 reached zero value, which triggered RG1 failover during use of the show chassis cluster status command.

For RG2, the default weight of 255 is set for redundant Ethernet interface 2 (reth2). When interface monitoring is required, we recommend that you use the default weight when you do not have backup links like those in RG1. That is, if interface ge-0/0/3 is disabled, it immediately triggers failover because the weight becomes 0 (255 minus 225), as indicated in the next verification section.

Verify Interface Status After Disabling ge-0/0/3

Purpose

Verify that interface ge-0/0/3 is disabled on node 0.

Action

From configuration mode, enter the set interface ge-0/0/3 disable command.

Meaning

The sample output confirms that interface ge-0/0/3 is disabled.

Verify Chassis Cluster Status After Disabling Interface ge-0/0/3

Purpose

Verify the chassis cluster status, failover status, and redundancy group information.

Action

From operational mode, enter the show chassis cluster status command.

Meaning

Use the show chassis cluster status command to confirm that devices in the chassis cluster are communicating properly, with one device functioning as the primary node and the other as the secondary node.

Verify Chassis Cluster Interfaces After Disabling Interface ge-0/0/3

Purpose

Verify information about chassis cluster interfaces.

Action

From operational mode, enter the show chassis cluster interfaces command.

Meaning

The sample output confirms that monitoring interfaces ge-0/0/1, ge-0/0/2, and ge-0/0/3 are down.

Verify Chassis Cluster Information After Disabling Interface ge-0/0/3

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster information command.

Meaning

The sample output confirms that in node 0, monitoring interfaces ge-0/0/1, ge-0/0/2, and ge-0/0/3 are down.

In regard to RG1, allowing any interface in node 0 go up triggers a failover only if the preempt option is enabled. In the example, preempt is not enabled. Therefore the node should return to normal, with no monitor failure showing for RG1.

Verify Interface ge-0/0/2 Is Enabled

Purpose

Verify that interface ge-0/0/2 is enabled on node 0.

Action

From configuration mode, enter the delete interfaces ge-0/0/2 disable command.

Meaning

The sample output confirms that interface ge-0/0/2 disable is deleted.

Verify Chassis Cluster Status After Enabling Interface ge-0/0/2

Purpose

Verify the chassis cluster status, failover status, and redundancy group information.

Action

From operational mode, enter the show chassis cluster status command.

Meaning

Use the show chassis cluster status command to confirm that devices in the chassis cluster are communicating properly, with as one device functioning as the primary node and the other as the secondary node.

Verify Chassis Cluster Interfaces After Enabling Interface ge-0/0/2

Purpose

Verify information about chassis cluster interfaces.

Action

From operational mode, enter the show chassis cluster interfaces command.

Meaning

The sample output confirms that monitoring interfaces ge-0/0/1 and ge-0/0/3 are down. Monitoring interface ge-0/0/2 is up after the disable has been deleted.

Verify Chassis Cluster Information After Enabling Interface ge-0/0/2

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster information command.

Meaning

The sample output confirms that in node 0, monitoring interfaces ge-0/0/1 and ge-0/0/3 are down. Monitoring interface ge-0/0/2 is active after the disable has been deleted.

Verify Chassis Cluster RG2 Preempt

Purpose

Verify that the chassis cluster RG2 is preempted on node 0.

Action

From configuration mode, enter the set chassis cluster redundancy-group 2 preempt command.

Meaning

The sample output confirms that chassis cluster RG2 preempted on node 0.

In the next section, you check that RG2 fails over back to node 0 when preempt is enabled when the disabled node 0 interface is brought online.

Verify Chassis Cluster Status After Preempting RG2

Purpose

Verify the chassis cluster status, failover status, and redundancy group information.

Action

From operational mode, enter the show chassis cluster status command.

Meaning

Use the show chassis cluster status command to confirm that devices in the chassis cluster are communicating properly, with one device functioning as the primary node and the other as the secondary node.

Verify Interface ge-0/0/3 Is Enabled

Purpose

Verify that interface ge-0/0/3 is enabled on node 0.

Action

From configuration mode, enter the delete interfaces ge-0/0/3 disable command.

Meaning

The sample output confirms that interface ge-0/0/3 disable has been deleted.

Verify Chassis Cluster Status After Enabling Interface ge-0/0/3

Purpose

Verify the chassis cluster status, failover status, and redundancy group information.

Action

From operational mode, enter the show chassis cluster status command.

Meaning

Use the show chassis cluster status command to confirm that devices in the chassis cluster are communicating properly, with one device functioning as the primary node and the other as the secondary node.

Verify Chassis Cluster Interfaces After Enabling Interface ge-0/0/3

Purpose

Verify information about chassis cluster interfaces.

Action

From operational mode, enter the show chassis cluster interfaces command.

Meaning

The sample output confirms that monitoring interface ge-0/0/1 is down. Monitoring interfaces ge-0/0/2, and ge-0/0/3 are up after deleting the disable.

Verify Chassis Cluster Information After Enabling Interface ge-0/0/3

Purpose

Verify information about the statistics of the different objects being synchronized, the fabric and control interface hellos, and the status of the monitoring interfaces in the cluster.

Action

From operational mode, enter the show chassis cluster information command.

Meaning

The sample output confirms that in node 0, monitoring interface ge-0/0/1 is down. RG2 on node 0 state is back to primary state (because of the preempt enable) with a healthy weight of 255 when interface ge-0/0/3 is back up.