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

Configure file mirroring

Updated: March 2, 2026

Want to summarize with AI?

Overview

Learn how to enable and configure the file mirroring feature to synchronize files between Route Processors.

Use these steps to configure file mirroring:

Before you begin

File mirroring must be enabled explicitly on the router. It is not enabled by default.

Procedure

Ensure mirroring is enabled.

Example:

Router#show run mirror

Thu Jun 25 10:12:17.303 UTC
mirror enable
mirror checksum

Copy running configuration to harddisk:/mirror location.

Example:

Router#copy running-config harddisk:/mirror/run_config
Wed Jul  8 10:25:51.064 PDT
Destination file name (control-c to abort): [/mirror/run_config]?
Building configuration..
32691 lines built in 2 seconds (16345)lines/sec
[OK]

Verify the syncing of file copied to mirror directory, use the show mirror command.

Example:

Router#show mirror 
Wed Jul  8 10:31:21.644 PDT
% Mirror rsync is using checksum, this show command may take several minutes if you have many files. Use Ctrl+C to abort
MIRROR DIR: /harddisk:/mirror/
% Last sync of this dir ended at Wed Jul  8 10:31:11 2020
Location   |Mirrored |MD5 Checksum                     |Modification Time
--------------------------------------------------------------------------
run_config |yes      |76fc1b906bec4fe08ecda0c93f6c7815 |Wed Jul  8 10:25:56 2020

If..

Then..

the checksum is disabled

use the show mirror command to display the following output:

Router#show mirror
Wed Jul 8 10:39:09.646 PDT
MIRROR DIR: /harddisk:/mirror/
% Last sync of this dir ended at Wed Jul  8 10:31:11 2020
Location   |Mirrored |Modification Time 
-----------------------------------------
run_config |yes         |Wed Jul  8 10:25:56 2020

there is a mismatch during the syncing process

use show mirror mismatch command to verify:

Router# show mirror mismatch
Wed Jul  8 10:31:21.644 PDT
 MIRROR DIR: /harddisk:/mirror/
 % Last sync of this dir ended at Wed Jul  8 10:31:11 2020 
 Location  |Mismatch Reason     |Action Needed 
------------------------------------------------
 test.txt  |newly created item. |send to standby

Need help?

Open a support case

(Requires a Cisco Service Contract)

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.