# OSPF Virtual Router Settings

The Open Shortest Path First (OSPF) routing protocol is an Interior Gateway Protocol (IGP) that is used for routing within a single Autonomous System (AS). A router running OSPF distributes its state information by periodically flooding link-sate advertisements (LSAs) throughout the AS. Each OSPF router maintains a link-state database. The router uses the information from this database to determine the best path to any destination within the AS. You can create and configure an OSPF routing instance on your NetScreen device.

### To Create or Edit an OSPF Routing Instance

1. Enter the necessary information:

Advertising Default Route: Enable this feature if you want the current OSPF routing instance to advertise its default route.

Metric: Specifies the cost of the default route.

Metric-type: Select a metric type that indicates whether the method for evaluating a path into the current OSPF routing instance is a Type 1 or Type 2. A Type 1 route is a comparable route, with a lower cost than a Type 2 route. A Type 2 route is a non-comparable route, with a higher cost than a Type 1 route.

Always: Select this check box to indicate you want the current OSPF routing instance to always advertise its default route.

Automatically Generate Virtual Links: Select this check box to indicate you want the current OSPF routing instance to create a way of reaching another routing instance on the other side of the routing backbone when the current instance does not connect to the backbone. This connection is a virtual link.

Do Not Add Default-Route Learned in OSPF: Select this check box to indicate you want the current OSPF routing instance to retain its default route.

Prevent Hello Packet Flooding Attack: Select On to indicate you want to block streams of hello packets from the same router entering the current OSPF routing instance.

Max hello packet: Enter a value that indicates the maximum number of hello packets allowed to enter the current OSPF routing instance within a specified amount of time.

Prevent LSA Flooding Attack: Select On to indicate you want to block streams of LSA packets from the same router entering the current OSPF routing instance.

LSA Packet Threshold Time: Enter a value that indicates a time interval in seconds for which the current OSPF routing instance will evaluate how many LSAs enter the current OSPF routing instance.

Maximum LSAs: Enter a value that indicates the maximum number of LSAs allowed to enter the current OSPF routing instance within the amount of time specified in the LSA Packet Threshold Time box.

RFC-1583 compatible: Select this check box to ensure that the current OSPF routing instance operates within the routing environment specified by the Request for Comments 1583 document.

OSPF Enabled: Select whether the current OSPF routing instance is in the enabled state. OSPF routing instances can be in one of two states: enabled or disabled. The default is disabled. To have an active OSPF routing instance, you must enable it.

2. Click OK to save your changes and return to the Virtual Router Basic Configuration page. Click Apply to continue configuring the OSPF routing instance.

If you clicked Apply, the following links appear at the top of the page: Area, Summary Import, Redistributable Rules, and Virtual Link.

## Other Configurations

After you create an OSPF routing instance, you can perform the following configurations:

### To Configure OSPF Areas

To configure an OSPF area, click Area. For more information, see OSPF Areas.

### To Summarize Imported Routes into an OSPF Domain

To summarize imported routes into an OSPF domain, click Summary Import. For more information, see OSPF Summary Route Importation.

### To Configure Redistribution Rules for an OSPF Routing Instance

To configure OSPF redistribution rules, click Redistributable Rules. For more information, see OSPF Redistribution Rules.

### To Configure an OSPF Virtual Link

To configure virtual links, click Virtual Link. For more information, see OSPF Virtual Links.