Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


Example: Configuring Independent Micro BFD Sessions for LAG

This example shows how to configure an independent micro BFD session for aggregated Ethernet interfaces.


This example uses the following hardware and software components:

  • MX Series routers with Junos Trio chipset

  • T Series routers with Type 4 FPC or Type 5 FPC

    BFD for LAG is supported on the following PIC types on T-Series:

    • PC-1XGE-XENPAK (Type 3 FPC),

    • PD-4XGE-XFP (Type 4 FPC),

    • PD-5-10XGE-SFPP (Type 4 FPC),

    • 24x10GE (LAN/WAN) SFPP, 12x10GE (LAN/WAN) SFPP, 1X100GE Type 5 PICs

  • PTX Series routers with 24X10GE (LAN/WAN) SFPP

  • Junos OS Release 13.3 or later running on all devices


The example includes two routers that are directly connected. Configure two aggregated Ethernet interfaces, AE0 for IPv4 connectivity and AE1 for IPv6 connectivity. Configure micro BFD session on the AE0 bundle using IPv4 addresses as local and neighbor endpoints on both routers. Configure micro BFD session on the AE1 bundle using IPv6 addresses as local and neighbor endpoints on both routers. This example verifies that independent micro BFD sessions are active in the output.


Figure 1 shows the sample topology.

Figure 1: Configuring an Independent Micro BFD Session for LAGConfiguring an Independent Micro BFD Session for LAG


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, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

Router R0

Router R1

Configuring a Micro BFD Session for Aggregated Ethernet Interfaces


Step-by-Step Procedure

The following example requires that you navigate various levels in the configuration hierarchy. For information about navigating the CLI, see “Using the CLI Editor in Configuration Mode” in the CLI User Guide.


Repeat this procedure for Router R1, modifying the appropriate interface names, addresses, and any other parameters for each router.

To configure a micro BFD session for aggregated Ethernet interfaces on Router R0:

  1. Configure the physical interfaces.

  2. Configure the loopback interface.

  3. Configure an IP address on the aggregated Ethernet interface ae0 with either IPv4 or IPv6 addresses, as per your network requirements.

  4. Set the routing option, create a static route, and set the next-hop address.


    You can configure either an IPv4 or IPv6 static route, depending on your network requirements.

  5. Configure the Link Aggregation Control Protocol (LACP).

  6. Configure BFD for the aggregated Ethernet interface ae0, and specify the minimum interval, local IP address, and the neighbor IP address.

  7. Configure an IP addresse on the aggregated Ethernet interface ae1.

    You can assign either IPv4 or IPv6 addresses as per your network requirements.

  8. Configure BFD for the aggregated Ethernet interface ae1.


    Beginning with Junos OS Release 16.1, you can also configure this feature with the AE interface address as the local address in a micro BFD session.

    Beginning with Release 16.1R2, Junos OS checks and validates the configured micro BFD local-address against the interface or loopback IP address before the configuration commit. Junos OS performs this check on both IPv4 and IPv6 micro BFD address configurations, and if they do not match, the commit fails.

  9. Configure tracing options for BFD for troubleshooting.


From configuration mode, enter the show interfaces, show protocols, and show routing-options commands and confirm your configuration. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

If you are done configuring the device, commit the configuration.


Confirm that the configuration is working properly.

Verifying That the Independent BFD Sessions Are Up


Verify that the micro BFD sessions are up, and view details about the BFD sessions.


From operational mode, enter the show bfd session extensive command.


The Micro BFD field represents the independent micro BFD sessions running on the links in a LAG. The TX interval item, RX interval item output represents the setting configured with the minimum-interval statement. All of the other output represents the default settings for BFD. To modify the default settings, include the optional statements under bfd-liveness-detection statement.

Viewing Detailed BFD Events


View the contents of the BFD trace file to assist in troubleshooting, if required.


From operational mode, enter the file show /var/log/bfd command.


BFD messages are being written to the specified trace file.