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RIPng Import Policy

Understanding RIPng Import Policies to Filter Routes

The default RIPng import policy is to accept all received RIPng routes that pass a validity check. To filter routes being imported by the local routing device from its neighbors, include the import statement and list the names of one or more policies to be evaluated. If you specify more than one policy, they are evaluated in order (first to last) and the first matching policy is applied to the route. If no match is found, the local routing device does not import any routes.

Example: Applying Policies to RIPng Routes Imported from Neighbors

This example shows how to configure an import policy in a RIPng network.

Requirements

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

Overview

In this example, Device R2 has several extra loopback interface addresses configured to simulate additional networks.

Device R1 has an import policy that accepts the fe80::/64 and 2001:db8::/64 routes and rejects all other routes. This means that the extra networks advertised by Device R2 are not accepted into Device R1’s routing table.

An export policy is also shown because an export policy is required as part of the minimum configuration for RIPng.

Figure 1 shows the topology used in this example.

Figure 1: RIPng Import Policy Network TopologyRIPng Import Policy Network Topology

Figure 2 shows the configuration for all of the devices in Figure 1. The section ../example/ripng-import.html#configuration256__ripng-import-step-by-step describes the steps on Device R1.

Topology

Configuration

Procedure

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

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 a RIPng import policy:

  1. Configure the network interfaces.

    This example shows multiple loopback interface addresses to simulate attached networks.

  2. Create the RIPng group and add the interface.

    To configure RIPng in Junos OS, you must configure a group that contains the interfaces on which RIPng is enabled. You do not need to enable RIPng on the loopback interface.

  3. Create the routing policy to advertise both direct and RIPng-learned routes.

  4. Apply the routing policy.

    In Junos OS, you can only apply RIPng export policies at the group level.

  5. Configure the import policy.

  6. Apply the import policy.

Results

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

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

Verification

Confirm that the configuration is working properly.

Looking at the Neighbor Addresses for Device R2

Purpose

Determine the neighbor address that Device R2 is using for Device R1.

Action

From operational mode, enter the show ripng neighbor command.

Meaning

Device R2 is using the fe80::2a0:a514:0:24c address to send routes to Device R1.

Looking at the Routes That Device R2 Is Advertising to Device R1

Purpose

Verify that Device R2 is sending the expected routes.

Action

From operational mode, enter the show route advertising-protocol ripng command.

Meaning

Device R2 is sending the extra loopback interface /128 routes to Device R1.

Looking at the Routes That Device R1 Is Receiving from Device R2

Purpose

Verify that Device R1 is receiving the expected routes.

Action

From operational mode, enter the show route receive-protocol ripng command.

Meaning

The output shows that the extra loopback interface addresses are excluded.

Checking the Routing Table

Purpose

Verify that the routing table is populated with the expected routes.

Action

From operational mode, enter the show route protocol ripng command.

Meaning

The output shows that the routes have been learned from Device R2 and Device R3.

If you delete or deactivate the import policy, the routing table contains the extra loopback interface routes.

Example: Testing a Routing Policy with Complex Regular Expressions

This example shows how to test a routing policy using the test policy command to ensure that the policy produces the results that you expect before you apply it in a production environment. Regular expressions, especially complex ones, can be tricky to get right. This example shows how to use the test policy command to make sure that your regular expressions have the intended effect.

Requirements

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

Overview

This example shows two routing devices with an external BGP (EBGP) connection between them. Device R2 uses the BGP session to send customer routes to Device R1. These static routes have multiple community values attached.

To test a complex regular expression, Device R2 has a policy called test-regex that locates routes. The policy is configured like this:

This regular expression matches community values beginning with either 1 or 3.

Topology

Figure 17 shows the sample network.

Figure 2: Routing Policy Test for Complex Regular ExpressionsRouting Policy Test for Complex Regular Expressions

CLI Quick Configuration shows the configuration for all of the devices in Figure 17.

The section ../../routing-policy/topics/example/policy-testing.html#configuration271__policy-test-regex-st describes the steps on Device R2.

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

Procedure

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.

To configure Device R2:

  1. Configure the interfaces.

  2. Configure BGP.

    Apply the import policy to the BGP peering session with Device R2.

  3. Configure the routing policy that sends static routes.

  4. Configure the routing policy that tests a regular expression.

  5. Configure the static routes and attaches community values.

  6. Configure the autonomous system (AS) number and the router ID.

    This affects Device R2’s routing table, and as no impact on Device R1 and Device R3.

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.

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

Verification

Confirm that the configuration is working properly.

Test to See Which Communities Match the Regular Expression

Purpose

You can test the regular expression and its policy by using the test policypolicy-name command.

Action
  1. On Device R2, run the test policy test-regex 0/0 command.

  2. On Device R2, change the regular expression to match a community value containing any number of instances of the digit 2.

  3. On Device R2, rerun the test policy test-regex 0/0 command.

Meaning

The 172.16.1.0 /24 and 172.16.3.0/24 routes both have communities attached that match the ^64510:[13].*$ expression. The 172.16.2.0/24 route has communities that match the ^65020:2+$ expression.