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Chassis Cluster Redundant Ethernet Interfaces

This topic explains that a redundant Ethernet (reth) interface is a pseudo‑interface that includes at least one physical interface from each node in a cluster. In a chassis cluster configuration, the reth interface on the active node is responsible for forwarding traffic.

Use Feature Explorer to confirm platform and release support for specific features.

Review the Platform-Specific Redundant Ethernet Interfaces Behavior section for notes related to your platform.

See the Additional Platform Information section for more information.

Redundant Ethernet Interfaces

A redundant Ethernet (reth) interface must include, at minimum, a pair of Fast Ethernet interfaces or a pair of Gigabit Ethernet interfaces, referred to as child interfaces of the reth interface (the redundant parent). If two or more child interfaces from each node are assigned to the reth interface, a redundant Ethernet link aggregation group can be formed.

A redundant Ethernet (reth) interface provides link redundancy by grouping multiple physical Ethernet interfaces from different cluster nodes into a single logical interface.

A reth interface must include, at minimum, one pair of physical Ethernet interfaces—one from each node in the chassis cluster. These physical interfaces are referred to as child interfaces, and the logical reth interface is referred to as the parent interface.

Interface Requirements and Restrictions

  • A redundant Ethernet interface must be configured using matching interface types and speeds on both nodes.

Supported combinations include:

  • Fast Ethernet interfaces

  • Gigabit Ethernet interfaces

  • Mixing different Ethernet interface types or speeds within a single reth interface is not supported.

  • Firewalls do not support combining Fast Ethernet and Gigabit Ethernet interfaces in the same redundant Ethernet bundle.

  • If two or more child interfaces from each node are assigned to a single reth interface, the configuration operates as a redundant Ethernet link aggregation group.

Configuration Guidelines

  • In configuration statements, a redundant Ethernet interface is referenced using the reth prefix (for example, reth0).
  • Child interfaces are associated with the redundant Ethernet interface as part of the child interface configuration.
  • A child interface inherits most of its configuration parameters from its redundant Ethernet parent interface.

The maximum number of redundant Ethernet interfaces supported varies by device type, as shown in Additional Platform Information. The number of redundant Ethernet interfaces configured on a device determines the number of redundancy groups that can be created on the Firewalls.

Promiscuous Mode Support

  • You can enable promiscuous mode on reth interfaces. On a Layer 3 Ethernet interface, this mode forwards all received packets on the interface to the central point, or Services Processing Unit (SPU), regardless of the packet's destination MAC address. For redundant Ethernet interfaces, enabling promiscuous mode automatically applies it to associated child physical interfaces.

To enable promiscuous mode on a redundant Ethernet interface, use the promiscuous-mode statement at the [edit interfaces] hierarchy.

A redundant Ethernet interface inherits its failover behavior from the redundancy group x to which it is assigned. The redundant Ethernet interface remains active as long as its primary child interface on the active node is operational. For example, if reth0 is associated with redundancy group 1 and redundancy group 1 is active on node 0, reth0 remains operational as long as the node 0 child interface of reth0 is UP.

When deploying Firewalls in chassis cluster mode, it is not recommended to configure local interfaces, or any combination of local interfaces, together with reth interfaces.

For example:

The following configuration shows a chassis cluster with redundant Ethernet interfaces in which some interfaces are configured as local interfaces:

The following configuration of chassis cluster redundant Ethernet interfaces, in which interfaces are configured as part of redundant Ethernet interfaces, is supported:

You can enable promiscuous mode on redundant Ethernet interfaces. When promiscuous mode is enabled on a Layer 3 Ethernet interface, all packets received on the interface are sent to the central point or Services Processing Unit (SPU), regardless of the destination MAC address of the packet. If you enable promiscuous mode on a redundant Ethernet interface, promiscuous mode is then enabled on any child physical interfaces.

To enable promiscuous mode on a redundant Ethernet interface, use the promiscuous-mode statement at the [edit interfaces] hierarchy.

IP-over-IP Tunneling

IP-IP tunneling is supported over the reth interface when firewalls are deploed in a chassis cluster configuration. Tunneling enables the encapsulation of one IP packet over another IP packet.

The tunnel configuration is created on both the primary and secondary devices. The traffic passing through the IP-IP tunnel is synced from primary device to secondary device. In the event of a failure on the primary device, the tunnel on the secondary device becomes active automatically. The traffic resumes on the secondary device in the event of the failure of the primary.

On firewalls, tunneling protocols use predefined internal logical interfaces that are created automatically by Junos OS during system boot:

  • Generic Routing Encapsulation (GRE) tunnels use the gr-0/0/0 interface.
  • IP-IP tunnels use the ip-0/0/0 interface. These internal tunnel interfaces are logical in nature and are not associated with any physical interfaces.

Example: Configure Chassis Cluster Redundant Ethernet Interfaces

This example shows how to configure chassis cluster redundant Ethernet interfaces. A redundant Ethernet interface is a pseudointerface that contains two or more physical interfaces, with at least one from each node of the cluster.

Requirements

Before you begin:

Overview

After you assign physical Ethernet interfaces to a redundant Ethernet interface, you configure all required settings at the redundant Ethernet (reth) interface level. The associated physical interfaces, referred to as child interfaces, automatically inherit the configuration of the reth parent interface.

If multiple child interfaces are configured under a single redundant Ethernet interface, all child interfaces must operate at the same interface speed.

In configuration commands, a redundant Ethernet interface is identified by the reth prefix (for example, reth0).

  • You can enable promiscuous mode on reth interfaces. On a Layer 3 Ethernet interface, this mode forwards all received packets on the interface to the central point, or Services Processing Unit (SPU), regardless of the packet's destination MAC address. For redundant Ethernet interfaces, enabling promiscuous mode automatically applies it to associated child physical interfaces.

To enable promiscuous mode on a redundant Ethernet interface, use the promiscuous-mode statement at the [edit interfaces] hierarchy.

Configuration

Configure Chassis Cluster Redundant Ethernet Interfaces for IPv4 Addresses

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.

Step-by-Step Procedure

To configure redundant Ethernet interfaces for IPv4:

  1. Bind redundant child physical interfaces to reth1.

  2. Bind redundant child physical interfaces to reth2.

  3. Add reth1 to redundancy group 1.

  4. Set the MTU size.

    The maximum transmission unit (MTU) set on the reth interface can be different from the MTU on the child interface.

  5. Assign an IP address to reth1.

  6. Associate reth1.0 to the trust security zone.

Configure Chassis Cluster Redundant Ethernet Interfaces for IPv6 Addresses

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.

Step-by-Step Procedure

To configure redundant Ethernet interfaces for IPv6:

  1. Bind redundant child physical interfaces to reth1.

  2. Bind redundant child physical interfaces to reth2.

  3. Add reth2 to redundancy group 1.

  4. Set the MTU size.

  5. Assign an IP address to reth2.

  6. Associate reth2.0 to the trust security zone.

Step-by-Step Procedure

To set the number of redundant Ethernet interfaces for a chassis cluster:

  1. Specify the number of redundant Ethernet interfaces:

Results

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

For brevity, this show command output includes only the configuration that is relevant to this example. Any other configuration on the system has been replaced with ellipses (...).

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

Verification

Confirm that the configuration is working properly.

Verify Chassis Cluster Redundant Ethernet Interfaces

Purpose

Verify the configuration of the chassis cluster redundant Ethernet interfaces.

Action

From operational mode, enter the show interfaces terse | match reth1 command:

Verify Chassis Cluster Control Links

Purpose

Verify information about the control interface in a chassis cluster configuration.

Action

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

Example: Configure Chassis Cluster Redundant Ethernet Interfaces on SRX4600

This example shows how to configure child links or physical links on SRX4600 device in chassis cluster mode.

Requirements

Before you begin:

Overview

You can configure up to eight number of child links for a reth bundle on SRX4600 devices per chassis.

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.

Configure redundant Ethernet interfaces

Step-by-Step Procedure

To configure redundant Ethernet interfaces:

  1. Bind eight redundant child physical interfaces to reth0.

  2. Bind redundant child physical interfaces to reth1.

  3. Specify the number of redundant Ethernet interfaces:

  4. Add reth0 to redundancy group 1.

  5. Assign an IP address to reth0.

  6. Add reth1 to redundancy group1.

  7. Assign an IP address to reth1.

  8. Associate reth0.0 to the trust security zone.

  9. Associate reth1.0 to untrust security zone.

Results

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

For brevity, this show command output includes only the configuration that is relevant to this example. Any other configuration on the system has been replaced with ellipses (...).

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

Verification

Confirm that the configuration is working properly.

Verify Chassis Cluster Redundant Ethernet Interfaces

Purpose

Verify the configuration of the chassis cluster redundant Ethernet interfaces on SRX4600 device.

Action

From operational mode, enter the show interfaces terse | match reth0 command:

Meaning

You can view the maximum number of configured child link interfaces of a reth bundle from four to eight in one chassis.

Verify Chassis Cluster Control Links

Purpose

Verify information about the control interface in a chassis cluster configuration.

Action

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

Example: Configure IP-over-IP Tunnel on Firewalls

This example shows how to create IP-IP tunnel with a forwarding next-hop to pass IPv4 traffic through the tunnel and synchronize the configuration from primary device to secondary device.

Requirements

Before you begin:

This example uses the following hardware and software components:

  • Junos OS Release 23.1R1 or later version.

  • SRX345 Device

Overview

Packets are routed to an internal interface, where they are encapsulated within an IP packet and forwarded to the destination address of the encapsulated packet. The IP-IP interface is an internal-only interface and is not associated with any physical interface. You must configure the interface to enable IP tunneling.

Topology

Figure 1 Illustrates IP-over-IP scenario with Firewalls operating in chassis cluster mode.

Figure 1: Configure Firewalls using IP-IP Tunnel Juniper SRX-A and SRX-B in HA cluster with control and fabric links for redundancy. IPIP tunnel on reth0 for external connectivity.

Configuration

Configure IP-IP tunnel with Chassis Cluster Redundant Ethernet Interfaces for IPv4 Addresses

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.

Step-by-Step Procedure

To configure redundant Ethernet interfaces for IPv4:

  1. Set up redundancy group 0 for the Routing Engine failover properties, and set up redundancy group 1 (all interfaces are in one redundancy group in this example) to define the failover properties for the redundant Ethernet interfaces.

  2. Set up the redundant Ethernet (reth) interfaces.

  3. Configure tunnel over redundant ethernet interface on both the nodes.

  4. Configure tunnel session on the peer.

  5. Configure routing-options on both the nodes:

  6. Configure fabric interfaces on both the nodes.

Results

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

For brevity, this show command output includes only the configuration that is relevant to this example. Any other configuration on the system has been replaced with ellipses (...).

Verification

Purpose

Display the information about chassis cluster interfaces and status.

Action

From operational mode, enter the show chassis cluster interfaces,show chassis cluster status, and show security flow session command.

Meaning

The chassis cluster configuration displays the reth interface as the bind interface to exchange routes through IP-over-IP tunnel.

Platform-Specific Redundant Ethernet Interfaces Behavior

Use Feature Explorer to confirm platform and release support for specific features.

Use the following table to review platform-specific behaviors for your platform.

Platform

Difference

SRX Series

  • SRX300, SRX320, SRX340, SRX345, SRX380 Firewalls that support redundant ethernet interfaces, the number of child interfaces is restricted to 16 on the reth interface (eight per node).

  • SRX300, SRX320, SRX340, SRX345, SRX380, SRX1500, and SRX1600 Firewalls that support Point-to-Point Protocol over Ethernet (PPPoE) over redundant Ethernet (reth) interface in chassis cluster mode, allows an existing PPPoE session to continue without starting a new PPP0E session in the event of a failover.

Additional Platform Information

Use Feature Explorer to confirm platform and release support for specific features.

Additional Platforms may be supported.

Platform

Redundant Ethernet (reth) interfaces

SRX4100 and SRX4200

10-Gigabit Ethernet (xe)

SRX5600 and SRX5800

10-Gigabit Ethernet (xe)

40-Gigabit Ethernet

100-Gigabit Ethernet

Platform

Logical Interfaces on reth interfaces

SRX300, SRX320, SRX340, SRX345, SRX380, SRX1500, SRX1600, SRX2300, SRX4120, SRX4100, SRX4200, and SRX4300

1024

SRX4600 and SRX5000 line of Firewalls

4096

Platform

Maximum Number of reth Interfaces

SRX300, SRX320, SRX340, SRX345, and SRX380

128

SRX1500

128

SRX1600

128

SRX2300, SRX4120

128

SRX4100, SRX4200, and SRX4300

128

SRX4600

128

SRX5000 line of Firewalls

128

Change History Table

Feature support is determined by the platform and release you are using. Use Feature Explorer to determine if a feature is supported on your platform.

Release
Description
12.1X45-D10
Starting with Junos OS Release 12.1X45-D10 and later, sampling features such as flow monitoring, packet capture, and port mirroring are supported on reth interfaces.