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Example: Configuring a Filter to Set the DSCP Bit to Zero

 

This example shows how to configure a standard stateless firewall filter based on the Differentiated Services code point (DSCP).

Requirements

No special configuration beyond device initialization is required before configuring this example.

Overview

In this example, you use a stateless firewall filter to match packets on DSCP bit patterns. If the DSCP is 2, the packet is classified to the best-effort forwarding class, and the DSCP is set to 0. If the DSCP is 3, the packet is classified to the best-effort forwarding class.

Configuration

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.

To configure this example, perform the following tasks:

CLI Quick Configuration

To quickly configure this example, copy the following configuration commands into a text file, remove any line breaks, and then paste the commands into the CLI at the [edit] hierarchy level.

Configure the Stateless Firewall Filter

Step-by-Step Procedure

To configure the stateless firewall filter filter1:

  1. Create the stateless firewall filter.

  2. Configure the first term to match a packet with a DSCP of 2, change the DSCP to 0, and classify the packet to the best-effort forwarding class.

  3. Configure the other term to match a packet with a DSCP of 3 and classify the packet to the best-effort forwarding class.

Apply the Stateless Firewall Filter to a Logical Interface

Step-by-Step Procedure

To apply the stateless firewall filter to the logical interface corresponding to the VPN routing and forwarding (VRF) instance:

  1. Configure the logical interface to which you will apply the stateless firewall filter.

  2. Apply the stateless firewall filter to the logical interface.

Confirm and Commit Your Candidate Configuration

Step-by-Step Procedure

To confirm and then commit your candidate configuration:

  1. Confirm the configuration of the stateless firewall filter by entering the show firewall configuration mode command. If the command output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

  2. Confirm the configuration of the interface by entering the show interfaces configuration mode command. If the command output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

  3. If you are done configuring the device, commit your candidate configuration.

Verification

To confirm that the configuration is working properly, enter the following operational mode commands: