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Example: Applying Policies to RIP Routes Imported from Neighbors

Understanding RIP Import Policy

The default RIP import policy is to accept all received RIP routes that pass a sanity 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 RIP Routes Imported from Neighbors

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

• Requirements
• Overview
• Configuration
• Verification

Requirements

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

Overview

In this example, Device R1 has an import policy that accepts the 10/8 and 192.168/16 RIP routes and rejects all other RIP routes. This means that the 172.16/16 RIP routes are excluded from Device R1’s routing table.

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

Figure 1 shows the topology used in this example.

Figure 1: RIP Import Policy Network 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 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.

Step-by-Step Procedure

1. Configure the network interfaces.

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

   [edit interfaces]user@R1# set fe-1/2/0 unit 1 family inet address 10.0.0.1/30
   user@R1# set lo0 unit 1 family inet address 172.16.0.1/32user@R1# set lo0 unit 1 family inet address 192.168.1.1/32
2. Create the RIP group and add the interface.

   To configure RIP in Junos OS, you must configure a group that contains the interfaces on which RIP is enabled.

   You do not need to enable RIP on the loopback interface.

   [edit protocols rip group rip-group]user@R1# set neighbor fe-1/2/0.1
3. Create the routing policy to advertise both direct and RIP-learned routes.
   [edit policy-options policy-statement advertise-routes-through-rip term 1]user@R1# set from protocol directuser@R1# set from protocol ripuser@R1# set then accept
4. Apply the routing policy.

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

   [edit protocols rip group rip-group]user@R1# set export advertise-routes-through-rip
5. Configure the import policy.
   [edit policy-options policy-statement rip-import]user@R1# set term 1 from protocol ripuser@R1# set term 1 from route-filter 10.0.0.0/8 orlongeruser@R1# set term 1 from route-filter 192.168.0.0/16 orlongeruser@R1# set term 1 then acceptuser@R1# set term 2 then reject
6. Apply the import policy.
   [edit protocols rip]user@R1# set import rip-import

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 Routes That Device R2 Is Advertising to Device R1
• Looking at the Routes That Device R1 Is Receiving from Device R2
• Checking the Routing Table
• Testing the Import Policy

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 rip command.

inet.0: 11 destinations, 11 routes (11 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.0.0.4/30        *[Direct/0] 2d 01:17:44
                    >    via fe-1/2/0.5
172.16.2.2/32      *[Direct/0] 2d 04:09:52
                    >    via lo0.2
172.16.3.3/32      *[RIP/100] 23:40:02, metric 2, tag 0
                    > to 10.0.0.6 via fe-1/2/0.5
192.168.2.2/32     *[Direct/0] 2d 04:09:52
                    >    via lo0.2
192.168.3.3/32     *[RIP/100] 23:40:02, metric 2, tag 0
                    > to 10.0.0.6 via fe-1/2/0.5

Meaning

Device R2 is sending 172.16/16 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 rip command.

inet.0: 8 destinations, 8 routes (8 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.0.0.4/30        *[RIP/100] 01:06:03, metric 2, tag 0
                    > to 10.0.0.2 via fe-1/2/0.1
192.168.2.2/32     *[RIP/100] 01:06:03, metric 2, tag 0
                    > to 10.0.0.2 via fe-1/2/0.1
192.168.3.3/32     *[RIP/100] 01:06:03, metric 3, tag 0
                    > to 10.0.0.2 via fe-1/2/0.1

Meaning

The output shows that the 172.16/16 routes 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 rip command.

inet.0: 8 destinations, 8 routes (8 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.0.0.4/30        *[RIP/100] 00:54:34, metric 2, tag 0
                    > to 10.0.0.2 via fe-1/2/0.1
192.168.2.2/32     *[RIP/100] 00:54:34, metric 2, tag 0
                    > to 10.0.0.2 via fe-1/2/0.1
192.168.3.3/32     *[RIP/100] 00:54:34, metric 3, tag 0
                    > to 10.0.0.2 via fe-1/2/0.1
224.0.0.9/32       *[RIP/100] 00:49:00, metric 1
                         MultiRecv

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 172.16/16 routes.

Testing the Import Policy

Purpose

By using the test policy command, monitor the number of rejected prefixes.

Action

From operational mode, enter the test policy rip-import 172.16/16 command.

Policy rip-import: 0 prefix accepted, 1 prefix rejected

Meaning

The output shows that the policy rejected one prefix.