Rate and give feedback:  Feedback Received. Thank You!

Rate and give feedback: 

X

This document helped resolve my issue

Yes No

Additional Comments

800 characters remaining

May we contact you if necessary?

Name:  

E-mail: 

Enter a valid Email ID

Need product assistance? Contact Juniper Support

Submit

This site is protected by hCaptcha and its Privacy Policy and Terms of Service apply.

English  

English

Example: Configuring an OSPFv2 Interface on a Nonbroadcast Multiaccess Network

Requirements

Before you begin:

• Configure the router identifiers for the devices in your OSPF network. See Example: Configuring an OSPF Router Identifier.
• Control OSPF designated router election. See Example: Controlling OSPF Designated Router Election.
• Configure a multiarea OSPF network. See Example: Configuring a Multiarea OSPF Network.

Overview

When you configure OSPFv2 on an NBMA network, you can use nonbroadcast mode rather than point-to-multipoint mode. Using this mode offers no advantages over point-to-multipoint mode, but it has more disadvantages than point-to-multipoint mode. Nevertheless, you might occasionally find it necessary to configure nonbroadcast mode to interoperate with other equipment. Because there is no autodiscovery mechanism, you must configure each neighbor.

Nonbroadcast mode treats the NBMA network as a partially connected LAN, electing designated and backup designated routers. All routing devices must have a direct connection to both the designated and backup designated routers, or unpredictable results occur.

When you configure the interface, specify either the IP address or the interface name. Using both the IP address and the interface name produces an invalid configuration. For nonbroadcast interfaces, specify the IP address of the nonbroadcast interface as the interface name.

• interface-type nbma—Sets the interface to run in NBMA mode. You must explicitly configure the interface to run in NBMA mode.
• neighbor address <eligible>—Specifies the IP address of the neighboring device. OSPF routing devices normally discover their neighbors dynamically by listening to the broadcast or multicast hello packets on the network. Because an NBMA network does not support broadcast (or multicast), the device cannot discover its neighbors dynamically, so you must configure all the neighbors statically. To configure multiple neighbors, include multiple neighbor statements. If you want the neighbor to be a designated router, include the eligible keyword.
• poll-interval—Specifies the length of time, in seconds, before the routing device sends hello packets out of the interface before it establishes adjacency with a neighbor. Routing devices send hello packets for a longer interval on nonbroadcast networks to minimize the bandwidth required on slow WAN links. The range is from 1 through 255 seconds. By default, the device sends hello packets out the interface every 120 seconds before it establishes adjacency with a neighbor.

  Once the routing device detects an active neighbor, the hello packet interval changes from the time specified in the poll-interval statement to the time specified in the hello-interval statement.

Configuration

CLI Quick Configuration

To quickly configure an OSPFv2 interface on an NBMA network, copy the following commands and paste them into the CLI.

Step-by-Step Procedure

1. Configure the interface.
   [edit]user@host# set interfaces at-0/1/0 unit 0 family inet address 192.0.2.1
2. Create an OSPF area.
   [edit]user@host# edit protocols ospf area 0.0.0.1
3. Assign the interface to the area.
   In this example, include the eligible keyword to allow the neighbor to be a designated router.
   [edit protocols ospf area 0.0.0.1 ]user@host# set interface at-0/1/0 interface-type nbma neighbor 192.0.2.2 eligible
4. Configure the poll interval.
   [edit protocols ospf area 0.0.0.1 ]user@host# set interface at-0/1/0 poll-interval 130
5. If you are done configuring the device, commit the configuration.
   [edit protocols ospf area 0.0.0.1 ]user@host# commit

Results

Confirm your configuration by entering the show interfaces and the show protocols ospf commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

Verification

Confirm that the configuration is working properly.

Verifying the OSPF Interface

Purpose

Verify the interface configuration. Confirm that the Type field displays NBMA.

Action

From operational mode, enter the show ospf interface detail command.