Restoring Cisco Router Configuration

In this section we will look at the three methods to restore a Cisco router configuration.

Method 1: Copy and Paste

One method to restore a Cisco router configuration is to copy and paste the configuration commands directly into the console session.

1. Connect to the router via console or telnet/SSH
2. Enter global configuration mode: configure terminal
3. Copy your saved configuration from a text file
4. Paste the configuration commands line by line
5. Exit configuration mode: exit
6. Save the configuration: copy running-config startup-config

Advantages: Simple and doesn't require additional protocols or servers.

Disadvantages: Time-consuming for large configurations and prone to errors if lines are dropped.

Method 2: TFTP Server

Using a TFTP (Trivial File Transfer Protocol) server is the most common method for restoring router configurations.

Prerequisites:

• TFTP server software running on a network-connected computer
• Router must have IP connectivity to the TFTP server
• Configuration file saved on the TFTP server

Steps:

1. Verify connectivity to TFTP server: ping [tftp-server-ip]
2. Save the configuration: copy running-config startup-config

Copy the configuration from TFTP server to running configuration:

Router# copy tftp running-config
Address or name of remote host []? [tftp-server-ip]
Source filename []? [configuration-filename]
Destination filename [running-config]? [press Enter]

You can also copy directly to startup-config:

Router# copy tftp startup-config

Method 3: USB Flash Drive

Modern Cisco routers support USB flash drives, making configuration restoration very convenient.

Steps:

1. Insert the USB flash drive containing your configuration file
2. Verify the USB drive is recognized: show file systems
3. List files on the USB drive: dir usbflash0:
4. Save the configuration: copy running-config startup-config

Copy the configuration file:

Router# copy usbflash0:[filename] running-config

Important Considerations

• Merge vs Replace: When copying to running-config, the new configuration merges with existing settings. To completely replace the configuration, copy to startup-config and reload the router.
• Syntax Errors: If the configuration file contains errors, the router will reject invalid commands and continue with valid ones.
• Memory: Ensure the router has sufficient memory to load the configuration file.
• Access Control: Make sure you have the appropriate privilege level (usually level 15) to perform configuration restoration.

Best Practices

• Always verify the configuration after restoration using show running-config
• Test critical functions like routing, interfaces, and access control
• Keep multiple backup copies in different locations
• Document the date and purpose of each configuration backup
• Use version control for configuration files when possible

Understanding these restoration methods ensures you can quickly recover from configuration loss or corruption, minimizing network downtime and maintaining business continuity.