Example: Configuring a Multiarea OSPF Network

This example shows how to configure a multiarea OSPF network. To reduce traffic and topology maintenance for the devices in an OSPF autonomous system, you can group them into multiple areas.

• Requirements
• Overview
• Configuration
• Verification

Requirements

Before you begin:

1. Configure network interfaces. See the Junos OS Interfaces Configuration Guide for Security Devices.
2. Configure security filters. See the Junos OS Security Configuration Guide.
3. Configure the router identifiers for the devices in your OSPF network. See Example: Configuring an OSPF Router Identifier.
4. Control OSPF designated router election. See Example: Controlling OSPF Designated Router Election.
5. Configure a single-area OSPF network. See Example: Configuring a Single-Area OSPF Network.

Overview

To activate OSPF on a network, you must enable the protocol on all interfaces within the network on which OSPF traffic is to travel. To enable OSPF, you must configure one or more interfaces on the device within an OSPF area. Once the interfaces are configured, OSPF LSAs are transmitted on all OSPF-enabled interfaces, and the network topology is shared throughout the network.

In Figure 1, router B resides in the backbone area of the AS. The backbone area is always assigned area ID 0.0.0.0. (All area IDs must be unique within an AS.) All other networks or areas in the AS must be directly connected to the backbone area by a router that has interfaces in more than one area. In this example, these area border routers are A, C, D, and E. You create an additional area (area 2) and assign it unique area ID 0.0.0.2, and then add interface ge-0/0/0 to the OSPF area.

To reduce traffic and topology maintenance for the devices in an OSPF autonomous system, you can group them into multiple areas as shown in Figure 1.

Configuration

Step-by-Step Procedure

To configure a multiarea OSPF network:

1. Configure the multiarea OSPF network.
   [edit]user@host# set protocols ospf area 0.0.0.2 interface ge-0/0/0
2. If you are done configuring the device, commit the configuration.
   [edit]user@host# commit

Verification

To verify the configuration is working properly, enter the show protocols ospf command.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices

• Understanding OSPF Areas, Area Border Routers, and Backbones

• OSPF Overview

• OSPF Configuration Overview

• Verifying an OSPF Configuration