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Example: Configuring IS-IS Flood Group


This example uses the following hardware and software components:

  • Four MX Series routers.

  • Junos OS Release 16.2 or future release.

Before you begin:

  1. Configure IS-IS routing protocol on the routers.

  2. Configure IS-IS interfaces with specific area IDs to modify the flood behavior as per your requirements.


Starting with Junos OS Release 16.2, IS-IS has support for flood-group.


In this topology, flood-group is configured on router R2.

Figure 1: Flood Group Topology


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.






1. commit after every configuration.

2. Following is the output before configuring flood-group on R2. You will see the link-state packets (LSPs) of R1, R2, R3 and R4.

From operational mode, run the show isis database command on router R1.


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 Junos OS CLI User Guide.

Flood-group functionality check:

  1. Deactivate protocol IS-IS on routers R1 and R2

  2. Configure flood-group on interface of router R2: set protocol isis interface interface flood-group flood-group-area-ID

  3. Activate protocol IS-IS on routers R1 and R2 and wait until the adjacency comes up.


Verifying the IS-IS Database


Verify IS-IS database.



Following is the output after configuring flood-group on R2. show isis database on router R1 will show LSPs from router R1 and router R2 only. flood-group is applicable to non self-originated LSPs only.

From operational mode, run the show isis database command on router R1.