Steps For Verifying Flash Memory in Cisco iOS

Flash memory is another name for the sort of memory frequently found in routers. It is a memory that can be read and written too, so data can be saved even if the system is restarted or shut down. The Flash contains the IOS (Router Operating System) that is currently in use.

Memory types on a Cisco device:

Four separate types of memory, each employed for a different function, are often included in Cisco devices. These four varieties are:

• A bootstrap software that is used to start the boot process is stored in read-only memory or ROM. This sort of memory is read-only, therefore changes cannot be made to it.
• The device’s routing tables and current configuration are kept in RAM (random access memory). When a device is rebooted, this form of memory loses its data.
• Images of the iOS software are kept in flash memory. It may also be used to store other items, such as configuration files for backups. even after a device restart, it keeps its content.
• Startup configuration files are typically stored in NVRAM (Non-volatile RAM). Even after a device shuts down or restarts, this kind of memory keeps its data.

Memory	Volatile / Non-Volatile	Stores
RAM	Volatile	Running IOS Running configuration file IP routing and ARP tables Packet buffer
ROM	Non-Volatile	Bootup instructions Basic diagnostic software Limited IOS
NVRAM	Non-Volatile	Startup configuration file
Flash	Non-Volatile	IOS Other system files

Steps To Verifying Flash Memory in Cisco iOS:

There are various folders in the Cisco IOS File System (IFS). The directories that are accessible vary by device. The IFS also permits the creation of subdirectories on a disc or in flash memory. 

Flash is the current default file system, the asterisk sign indicates which is placed next to it. The bootable IOS is located in the flash and is indicated by the pound sign (#) attached to the flash.

The following command is used to check or verify the flash memory in Cisco IOS:

Command to check flash memory = dir flash:

Backup and Restoring using Text files:

Backup: We can back up the configuration file using Tera Term and restore the settings from the text file if necessary. The following are the steps for backing up and restoring data using Tera Term:

1. Click Log in Tera Term’s File menu.
2. Choose a location to save the file after that. Tera Term will now begin capturing.
3. Execute the show running-config or show startup-config command at the privileged EXEC prompt once the capture has begun. The selected file will be referenced in the text that is displayed in the Tera Terminal.
4. Select Close in the Tera Term: Log window after the capture is finished.
5. Check that the file is not corrupted by viewing it at the specified location.

Restoring: The Inter Operating System runs each line of a text file’s configuration as it is copied from it and pasted into a terminal window. Therefore, it will be necessary to alter the captured file to ensure that any non-command text is removed and that any encrypted passwords are displayed in plain form.

In order for the device to receive commands from the text file pasted into the terminal window, it must also be in the global configuration mode. The procedures for utilizing Tera Term to restore configuration are listed below.

1. Select Send File from the File menu in Tera Term.
2. To copy a configuration text file into the device, find it and click Open.
3. Once the file is pasted into the device, Tera Term will display the text.

Backup and Restoring Configurations with TFTP:

Backup: On a TFTP (Trivial File Transfer Protocol) server, startup configuration or running configuration files can be kept and restored in the event of an issue. The network documentation should also provide the configuration file.

Use the copy running-config TFTP or copy startup-config TFTP commands to save the running configuration or the startup configuration file to a TFTP (Trivial File Transfer Protocol) server. The steps to backup the active configuration to a TFTP server are as follows:

1. Enter the hostname or IP address where the configuration file will be saved after performing the copy running-config TFTP command in user exec mode.
2. Give the configuration file a name by typing it in.
3. Enter to confirm each selection.

Restoring: Use the copy TFTP running-config or copy TFTP startup-config commands to retrieve the running configuration or the startup configuration from a TFTP (Trivial File Transfer Protocol) server. The methods to restore the active configuration from a TFTP server are as follows:

1. The hostname or IP address of the location where the configuration file is kept should be entered after running the copy TFTP running-config command in user exec mode.
2. Give the configuration file a name by typing it in.
3. Enter to make each selection official.

Backing Up and Restoring Using a USB:

Backup: Use the show file systems command in user exec mode to validate that the USB drive is present and that the drive’s name is correct before backing up to a USB port. Use the copy run usbflash0:/ command to copy the configuration file to the USB flash drive if it is present. Use the exact name of the flash drive as it appears in the file system.

The slash denotes the USB flash drive’s root directory. The IOS will then ask you for the filename. The router will then urge you to overwrite if the file has already been copied and is already present on the USB flash drive. Using the dir command, we can view the files and folders on the USB.

Restore: To restore a running configuration, issue the command copy usbflash0:/Router-Config running-config, where Router-Config is the name of the backup file on the USB.