Traffic Mirroring Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

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Configure forward-drop packets

Updated: March 2, 2026

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Overview

Learn how to configure a global session on the router to mirror forward-drop packets to a destination interface.

Perform the these steps on the router to configure a global session for mirroring forward-drop packets:

Procedure

1.

Configure the tunnel mode.

Example:

Router(config)# interface tunnel-ip 2
Router(config-if)# tunnel mode gre ipv4
2.

Configure the tunnel source.

Example:

Router(config-if)# tunnel source 20.20.20.20
3.

Configure the tunnel destination.

Example:

Router(config-if)# tunnel destination 192.1.1.3 
Router(config-if)# exit
4.

Configure a traffic mirroring session.

Example:

Router(config)# monitor-session mon2 ethernet
5.

Associate a destination interface with the traffic mirroring session.

Example:

Router(config)# destination interface tunnel-ip2
6.

Run drops command to start mirroring forward-drop packets.

Example:

Router(config)# drops packet-processing rx
Router(config)# commit
7.

Verify the forward-drop packets are mirrored using the show monitor-session command.

Example:

Router# show monitor-session mon2 status detail
Mon Aug 15 19:14:31.975 UTC
Monitor-session mon2
   Destination interface tunnel-ip2
   All forwarding drops:
      Direction: Rx
Source Interfaces
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