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Example: Redistributing OSPF Routes into IS-IS

 

This example shows how to redistribute OSPF routes into an IS-IS network.

Requirements

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

Overview

Export policy can be applied to IS-IS to facilitate route redistribution.

Junos OS does not support the application of import policy for link-state routing protocols like IS-IS because such policies can lead to inconsistent link-state database (LSDB) entries, which in turn can result in routing inconstancies.

In this example, OSPF routes 192.168.0/24 through 192.168.3/24 are redistributed into IS-IS area 49.0002 from Device R2.

In addition, policies are configured to ensure that Device R1 can reach destinations on the 10.0.0.44/30 network, and that Device R3 can reach destinations on the 10.0.0.36/30 network. This enables end-to-end reachability.

Figure 1 shows the topology used in this example.

Figure 1: IS-IS Route Redistribution Topology
IS-IS Route Redistribution Topology

CLI Quick Configuration shows the configuration for all of the devices in Figure 1. The section Step-by-Step Procedure describes the steps on Device R2. Step-by-Step Procedure describes the steps on Device R3.

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

Device R3

Step-by-Step Procedure

To configure Device R2:

  1. Configure the network interfaces.
  2. Configure IS-IS on the interface facing Device R1 and the loopback interface.
  3. Configure the policy that enables Device R1 to reach the 10.0.0.44/30 network.
  4. Apply the policy that enables Device R1 to reach the 10.0.0.44/30 network.
  5. Configure OSPF on the interfaces.
  6. Configure the OSPF route redistribution policy.
  7. Apply the OSPF route redistribution policy to the IS-IS instance.
  8. Configure the policy that enables Device R3 to reach the 10.0.0.36/30 network.
  9. Apply the policy that enables Device R3 to reach the 10.0.0.36/30 network.

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 multi-level IS-IS:

  1. Configure the network interfaces.

    Multiple addresses are configured on the loopback interface to simulate multiple route destinations.

  2. Configure static routes to the loopback interface addresses.

    These are the routes that are redistributed into IS-IS.

  3. Configure OSPF on the interfaces.
  4. Configure the OSPF policy to export the static routes.
  5. Apply the OSPF export policy.

Results

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

Device R2

Device R3

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

Verification

Confirm that the configuration is working properly.

Verifying OSPF Route Advertisement

Purpose

Make sure that the expected routes are advertised by OSPF.

Action

From operational mode on Device R2, enter the show route protocol ospf command.

user@R2> show route protocol ospf

Meaning

The 192.168/16 routes are advertised by OSPF.

Verifying Route Redistribution

Purpose

Make sure that the expected routes are redistributed from OSPF into IS-IS.

Action

From operational mode on Device R1, enter the show route protocol isis command.

user@R1> show route protocol isis

Meaning

The 192.168/16 routes are redistributed into IS-IS.

Verifying Connectivity

Purpose

Check that Device R1 can reach the destinations on Device R3.

Action

From operational mode, enter the ping command.

user@R1> ping 192.168.1.1

Meaning

These results confirm that Device R1 can reach the destinations in the OSPF network.