Example: Configuring External BGP Point-to-Point Peer Sessions

 

This example shows how to configure BGP point-to-point peer sessions.

Requirements

Before you begin, if the default BGP policy is not adequate for your network, configure routing policies to filter incoming BGP routes and to advertise BGP routes.

Overview

Figure 1 shows a network with BGP peer sessions. In the sample network, Device E in AS 17 has BGP peer sessions to a group of peers called external-peers. Peers A, B, and C reside in AS 22 and have IP addresses 10.10.10.2, 10.10.10.6, and 10.10.10.10. Peer D resides in AS 79, at IP address 10.21.7.2. This example shows the configuration on Device E.

Figure 1: Typical Network with BGP Peer Sessions
Typical Network with
BGP Peer Sessions

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

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To configure the BGP peer sessions:

  1. Configure the interfaces to Peers A, B, C, and D.
  2. Set the autonomous system (AS) number.
  3. Create the BGP group, and add the external neighbor addresses.
  4. Specify the autonomous system (AS) number of the external AS.
  5. Add Peer D, and set the AS number at the individual neighbor level.

    The neighbor configuration overrides the group configuration. So, while peer-as 22 is set for all the other neighbors in the group, peer-as 79 is set for neighbor 10.21.7.2.

  6. Set the peer type to external BGP (EBGP).

Results

From configuration mode, confirm your configuration by entering the show interfaces, show protocols, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Verifying BGP Neighbors

Purpose

Verify that BGP is running on configured interfaces and that the BGP session is active for each neighbor address.

Action

From operational mode, run the show bgp neighbor command.

user@E> show bgp neighbor

Verifying BGP Groups

Purpose

Verify that the BGP groups are configured correctly.

Action

From operational mode, run the show bgp group command.

user@E> show bgp group

Verifying BGP Summary Information

Purpose

Verify that the BGP configuration is correct.

Action

From operational mode, run the show bgp summary command.

user@E> show bgp summary