Example: Configuring IS-IS

 

This example shows how to configure IS-IS.

Requirements

No special configuration beyond device initialization is required before configuring this example.

Overview

In this example, you configure the two IS-IS routing devices in a single area. The devices have NET addresses 49.0002.0192.0168.0001.00 and 49.0002.0192.0168.0002.00 on the lo0 interfaces. Additionally, you configure the ISO family on the IS-IS interfaces.

For Junos OS security devices only, you configure the mode packet-based statement at the [edit security forwarding-options family iso] hierarchy level.

Figure 1 shows the topology used in this example.

Figure 1: Simple IS-IS Topology
Simple IS-IS Topology

CLI Quick Configuration shows the configuration for both of the devices in Figure 1. The section Step-by-Step Procedure describes the steps on Device R1.

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

Device R1

Device R2

Step-by-Step Procedure

The following example requires you to 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.

To configure IS-IS:

  1. Enable IS-IS if your router is in secure context.
  2. Create the interface that connects to Device R2, and configure the ISO family on the interface.
  3. Create the loopback interface, set the IP address, and set the NET address.
  4. Enable IS-IS on the interfaces.

Results

From configuration mode, confirm your configuration by entering the show interfaces, show protocols, and show security commands. 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, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Verifying IS-IS Interface Configuration

Purpose

Verify the status of the IS-IS-enabled interfaces.

Action

From operational mode, enter the show isis interface brief command.

user@R1> show isis interface brief

Meaning

Verify that the output shows the intended configuration of the interfaces on which IS-IS is enabled.

Verifying IS-IS Interface Configuration in Detail

Purpose

Verify the details of IS-IS-enabled interfaces.

Action

From operational mode, enter the show isis interface detail command.

user@R1> show isis interface detail

Meaning

Check the following output fields and verify that the output shows the intended configuration of IS-IS-enabled interfaces:

  • Interface—Interface configured for IS-IS.

  • State—Internal implementation information.

  • Circuit id—Circuit identifier.

  • Circuit type—Configured level of IS-IS:

    • 1—Level 1 only

    • 2—Level 2 only

    • 3—Level 1 and Level 2

  • link-state PDU interval—Time between IS-IS information messages.

  • L or Level—Type of adjacency:

    • 1—Level 1 only

    • 2—Level 2 only

    • 3—Level 1 and Level 2

  • Adjacencies—Adjacencies established on the interface.

  • Priority—Priority value established on the interface.

  • Metric—Metric value for the interface.

  • Hello(s)—Intervals between hello PDUs.

  • Hold(s)—Hold time on the interface.

Verifying IS-IS Adjacencies

Purpose

Display brief information about IS-IS neighbors.

Action

From operational mode, enter the show isis adjacency brief command.

user@R1> show isis adjacency brief

Meaning

Verify the adjacent routers in the IS-IS database.

Verifying IS-IS Adjacencies in Detail

Purpose

Display extensive information about IS-IS neighbors.

Action

From operational mode, enter the show isis adjacency extensive command.

user@R1> show isis adjacency extensive

Meaning

Check the following fields and verify the adjacency information about IS-IS neighbors:

  • Interface—Interface through which the neighbor is reachable.

  • L or Level—Configured level of IS-IS:

    • 1—Level 1 only

    • 2—Level 2 only

    • 3—Level 1 and Level 2

    An exclamation point before the level number indicates that the adjacency is missing an IP address.

  • State—Status of the adjacency: Up, Down, New, One-way, Initializing, or Rejected.

  • Event—Message that identifies the cause of a state.

  • Down reason—Reason the adjacency is down.

  • Restart capable—A neighbor is configured for graceful restart.

  • Transition log—List of transitions including When, State, and Reason.