OSPF Configuration 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, as explained in the steps that follow. To enable OSPF, you must configure one or more interfaces on the device within an OSPF area. Once the interfaces are configured, OSPF link-state advertisements (LSAs) are transmitted on all OSPF-enabled interfaces, and the network topology is shared throughout the network.

To configure the Juniper Networks device as a node in an OSPF network:

1. Configure network interfaces. See Configuring OSPF on Interfaces and the Junos OS Interfaces Configuration Guide for Security Devices.
2. Configure security filters. See Security Policies Overview in 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. Create the backbone area for your OSPF network and add the appropriate interfaces to the area. See Example: Configuring a Single-Area OSPF Network.

   Note: Once you complete this step, OSPF begins sending LSAs. No additional configuration is required to enable OSPF traffic on the network.

5. (Optional) Add additional areas to your network and configure area border routers. See Example: Configuring a Multiarea OSPF Network.
6. Enable dial-on-demand routing backup on the OSPF-enabled interface if you are configuring OSPF across a demand circuit such as an ISDN link. (You must have already configured an ISDN interface.) Because demand circuits do not pass all traffic required to maintain an OSPF adjacency (hello packets, for example), you configure dial-on-demand routing so individual nodes in an OSPF network can maintain adjacencies despite the lack of LSA exchanges. See the Junos OS Interfaces Configuration Guide for Security Devices.
7. (Optional) Reduce the amount of memory that the nodes use to maintain the topology database by configuring stub and not-so-stubby areas. See Example: Configuring OSPF Stub and Not-So-Stubby Areas.
8. (Optional) Ensure that only trusted routers participate in the autonomous system’s (AS’s) routing by enabling authentication. See Example: Enabling Authentication for OSPF Exchanges.
9. (Optional) Control the flow of traffic across the network by configuring path metrics and route selection. SeeExample: Controlling the Cost of Individual OSPF Network Segments and Example: Controlling OSPF Route Selection in the Forwarding Table.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices
• OSPF Overview
• Verifying an OSPF Configuration
• Configuring OSPF in the Junos Routing Protocols Configuration Guide
• Minimum OSPF Configuration in the Junos Routing Protocols Configuration Guide