TheKettleMaker

Cisco Files

The sections below will cover the following:

Review some common filesystems managed through the IOS
Discuss image files
Demonstrate some common ways to manage the IOS
Demonstrate how to backup configuration files using both the old & new way
Demonstrate how to filter output using command options and also how to add comments
Q & A to test your knowledge about what you learned
Click the terminal icon to the left and follow the steps under each section
Filesystems

Filesystems are typically structured like a tree, where all files will stem from root "/". The Cisco IOS manages multiple file systems that are identifed using a naming convention that is derived from either the device type or network service, followed by a colon. (Cisco, 2014).

Managed Filesystems

flash:/c1841-advipservicesk9-mz.124-10.bin

nvram:/startup-config    system:/running-config

In this section we will be discussing files on following devices in order to get a basic understanding of how our Cisco device works.

  • flash:
  • nvram:
  • system:
1
 Execute the following commands to view the available filesystems 
Router#show file systems
show file systems command

By default you are managing the root directory of the FAT filesystem on Flash:. This is also the default location that your Cisco device will look to load the Cisco IOS from. When executing the dir command, it will list the files in the current working directory and display it's location.

2
 Execute the following command to view the IOS image file 
Router#dir
dir command
3
 Execute the following command to verify the FAT filesystem is in use on that device 
Router#fsck flash:
fsck flash command

Once the operating system loads, your Cisco device will look to load any persistent configuration from nvram:/startup-config by default. If none exists within this container, then the device will load the default configuration.

4
 Execute the following command to view the startup-config container and any bytes of persistent configuration contained therein 
Router#dir nvram:
dir nvram command

Once the type of configuration is determined (persistent or default), the next step is to load it into system:/running-config.

5
 Execute the following command to view the running-config container and the number of bytes therein 
Router#dir system:
dir system command

Both the running-config and startup-config are considered files. However, you cannot delete them, only the bytes within them.

6
 Execute the following command and press the Enter key twice to delete the persistent bytes 
Router#delete nvram:startup-config
delete nvram:startup-config command

Anytime you see a zero or a five for the number of bytes, this means there is no persistent configuration.

7
 Execute the following command to verify 
Router#dir nvram:
dir nvram command
8
 Execute the following command to save the running configuration to persistent memory 
Router#copy running-config startup-config
copy run start command
9
 Execute the following command to verify 
Router#dir nvram:
dir nvram command

The shortest form of this command is cop ru st. However, an easier way to memorize a short form is displayed below.

10
 Execute the following command to do the same thing using a shorter form of the command 
Router#copy run start
copy run start command

This way of saving is useful in understanding how the process works. But, executing the write command can do the same thing.

11
 Execute the following command to issue a save an even easier way 
Router#write
write command
IOS

Your Cisco device contains a bunch of hardware and software that is capable of many features. However, the majority of these features are disabled by default. The way that you can enable them is through commands afforded by the Cisco IOS image file. However, not all image files are the same. Your Cisco IOS software is going to group commands based on the features that they can enable (Cisco, 2005).

feature-set hierarchy

The Cisco IOS is typically a compressed file that gets decompressed and loaded into RAM during boot-up. Two things when looking at the image descriptions below that may not be apparent to you; Think of the platform as a specific version of hardware and think of the train number as a specific version of software. The commands that are available to you are dependent on the IOS version and feature set.

image file name structure

The default storage location of this file is off root in flash:, which is also the default filesystem and working directory managed by a privilege level 15 user.

1
 Execute the following command to view the working directory, and the IOS image file within it 
Router#dir
dir command
2
 Execute the following command to verify that the IOS is an executable image file 
Router#show file information c1841-advipservicesk9-mz.124-15.T3.bin
show file information command

Commands are made available or retired based on a particular software release. The following commands can be used to verify the IOS version:

  • show flash:
  • show version
  • show running-config
3
 Execute the following command to view the IOS version from the image file 
Router#show flash:
show flash command
4
 Execute the following command to view the IOS version in the showput 
Router#show version
show version command
5
 Execute the following command to view the IOS version inside the configuration file 
Router#show running-config
show run command

A common practice is to search the documentation to see which IOS versions are supported by particular commands. Once this information is gleaned, the documentation will instruct the reader to use Cisco's Feature Navigator to see which images can be used (Click here to see this).

Managing IOS

The sub-sections will walk you through the following:

  • Managing IOS image files
    • USB Flash dongle
    • USB
  • Managing config files

USB Flash dongle

The Cisco IOS is loaded from flash:/ by default. Below will walk you through two ways to transfer the image file. Both of these methods require physical access to the equipment. However, this first method requires no command line knowledge and can be accompished following these steps:

  • Simply pop the flash card out of the 1841
  • Insert the card into the card reader
  • Insert the USB dongle into your workstation
  • Transfer the image to the external device
  • Pop the card out
  • Insert the card back into the 1841
  • Powercycle the device

Some networking devices that use flash will make it ejectable like the 1841.

ejectable flash

Doing so can offload the work of Level 2 & 3 engineers by enabling Level 1 techs to perform this task. Files can be easily transferred from a user's workstation onto flash, which can then be reinserted.

flash memory
flash memory dongle
file explorer

USB

This second method (USB) requires command line knowledge and this device is formatted with FAT-16, which is not compatible with FAT-32 (default).

USB port 1841

Below will walk you through the process of changing the image file.

1
 Issue the following key sequence (Ctrl^a n) to access a different console session. Then execute the following command to view the IOS image file 
Router#dir
dir command
2
 Execute the following command to verify the feature-set 
Router#show version
show version command

A common meaning for an asterisk is everything. The directory below only contains one file and the easiest way to delete it is to use this character.

3
 Execute the following command and press the Enter key twice to delete the image file 
Router#delete *
delete command
4
 Execute the following command to verify 
Router#dir
dir command
5
 Issue the following key sequence (Ctrl^a i) to insert a USB drive
system message
6
 Execute the following command to verify 
Router#show file systems
show file system command
7
 Execute the following command to view the image file stored on the external device 
Router#dir usbflash0:
dir usbflash0 command

Dots are used by filesystems to determine position. A single dot means current position, which in this case is flash:/.

8
 Execute the following command and press Enter to copy this image to flash: 
Router#copy usbflash0:c1841-advsecurityk9-mz.124-11.T3.bin .
copy from USB

Completed copy.

completed copy
9
 Execute the following command to verify 
Router#dir
dir command

The previous feature-set will remain until the system is powercycled.

10
 Execute the following command and press Enter to load the different feature-set 
Router#reload
reload command
11
 Once the device reboots, execute the following command to verify 
Router#show version
show version command
Storing Backups

Local backups are used mostly to correct human error. Below will walk through two methods of backing up configuration locally:

  • Old Way
  • New Way

Old Way

The old way to backup configuration, was to simply copy the contents of the running-config into another file.

1
 Execute the following command and press Enter to create a container used to house backup configuration files 
Router#mkdir BACKUP
make directory
2
 Execute the following command to verify it has been created 
Router#dir
dir command
3
 Execute the following command and press Enter to save the configuration 
Router#copy run BACKUP/R-Conf
storing backup
4
 Execute the following command to verify the backup exists 
Router#dir BACKUP
verifying backup
5
 Execute the following command and press the spacebar multiple times until you are returned to a prompt 
Router#more BACKUP/R-Conf
verifying write

Device hostnames are used for identification and must follow these rules:

  • Must start with a letter
  • Must end with a letter or number
  • Interior can include letters, numbers, and hypens
  • Must be less than 63 characters
6
 Execute the following command to make a configuration change 
Router(config)#hostname R1
configuring hostname
7
 Execute the following command and press Enter to revert the configuration back to a previous state 
R1(config)#do copy BACKUP/R-Conf run
do command

New Way

One part of human error is forgetting. The archive feature was introduced in release 12.3(4) and provides the capability to automate backups.

1
 Execute the following command to enter archive configuration mode 
Router(config)#archive
archive command
2
 Use Cisco's help to view the configuration options 
Router(config-archive)#?
context help
3
 Execute the following command to define the storage location and filename that includes a timestamp 
Router(config-archive)#path flash:/BACKUP/$t
defining backup location and file name
4
 Execute the following command to create a backup each time a save is issued 
Router(config-archive)#write-memory
testing backup
5
 Execute the following command to issue a save 
Router(config-archive)#do copy run start
testing backup
6
 Execute the following command to verify it's working 
Router(config-archive)#do dir BACKUP
verifying backups

Manual backups can also be performed using this feature.

7
 Execute the following command to create a backup without issuing a save 
Router#archive config
manual backup
8
 Execute the following command to verify 
Router#dir BACKUP
verifying backup
Working with Files

Knowing how to filter output and document tasks is key when managing devices. This section will demonstrate:

  • How to use output modifiers when managing files
  • How to add comments to files

Output Modifiers

Output modifiers are commonly used by operating systems to ease administration when working with files. This section will demonstrate some commands that can be used to filter text displayed within the CLI.

1
 Execute the following command to display the first page of the running-config 
Router#show running-config
viewing run conf

In order to view the whole file, both the Enter key and or the Spacebar must be pressed any number of times.

2
 Execute the following command to view some command arguments that can be used to filter what is displayed 
Router#show running-config ?
command options

During your CCNA training, interfaces, vty lines, and the console port (con 0) are common devices that will be configured.

3
 Execute the following command to view the configuration that pertains to FastEthernet0/1 
Router#show running-config interface FastEthernet0/1
show run interface

A pipe is commonly used for interprocess communication, where the output of one process is the input to another. A pipe is also commonly used with some sort of output modifier (ex. find, grep, etc.).

4
 Execute the following command to view some output modifiers available with our image 
Router#show running-config | ?
pipe options
5
 Execute the following command to view only the section of the config file that pertains to FastEthernet0/1 
Router#show running-config | section FastEthernet0/1
filtering parent with child
6
 Execute the following command to view all lines from the config file that match the pattern FastEthernet0/ 
Router#show running-config | include FastEthernet0/
filtering lines
7
 Execute the following command to start viewing the config file once the pattern vty is matched 
Router#show running-config | begin vty
begin at match

Comments

Documenting tasks is a recommended practice in everything IT. This section will demonstrate how to add commments to config files.

Tool Command Language (TCL) scripts are commonly used to automate tasks. But, here we will access a TCL shell to append a note to a configuration file. Below we are opening a channel to a specified file and adjusting the pointer to the end of the file. After the note is written, the channel is closed.

1
 Execute the following commands to append a note 
Router#tclsh
Router(tclsh)#set ch [open "flash:/BACKUP/-Dec-22-17:01:10.824-2" a]
Router(tclsh)#puts $ch "My added notes"
Router(tclsh)#close $ch
Router(tclsh)#tclquit
tcl script

The "end" keyword in the configuration files prevents all preceeding characters from being interpreted as commands.

2
 Execute the following command and press the spacebar multiple times to verify 
Router#more flash:/BACKUP/-Dec-22-17:01:10.824-2
verify write
Questions

Click the start button to review the questions that pertain to this section.