Cisco IOS & Router Config
Semester 2V2
Chapter 6
Routers boot Cisco IOS software from:
• Flash memory
• TFTP server
• ROM (not full Cisco IOS software)
Cisco IOS software allows you to use several alternatives to loading your
system. (router)
•You can specify other sources for the router to look for software.
•The router can use its own fallback sequence, as necessary, to load the software.
•
•The settings in the configuration register enable the alternatives.
Router Fallback Sequence
• It can use default Cisco IOS in Flash memory.
• If Flash memory is empty, the router can try its
next TFTP alternative.
The router uses the configuration register value to form a filename
from which to boot a default system image stored on a network
server.
• ROM may contain an older version of IOS
To check the boot field setting, and to verify the
config-register command, use the show version command.
[Router(config)# config-register]
Show Version Command
• Displays information about the Cisco IOS software version
that is currently running on the router.
• This includes the configuration register and the boot field
setting .
• The highlighted line at the bottom of the graphic shows the
system image file. You will learn about Cisco IOS software
Release 11.2 image naming conventions later in this lesson.
For now, notice the portion of the filename that indicates that
this image is for a Cisco 4500 platform.
• As it continues to output, the show version command
displays information about the type of platform on which the
version of Cisco IOS software is currently running.
Boot System Commands to Specify the
Fallback Sequence
• Flash memory - You can copy a system image by changing the electrically
erasable programmable read-only memory (EEPROM). The information stored
in Flash memory is not vulnerable to network failures that can occur when
loading system images from TFTP servers.
• Network server - In case Flash memory becomes corrupted, you provide for a
backup by specifying that a system image should be loaded from a TFTP server.
• ROM - If Flash memory is corrupted and the network server fails to load the
image, booting from ROM is the final bootstrap option in software.
However, the system image in ROM will likely be a subset of Cisco IOS
software, that lacks the protocols, features, and configurations of full Cisco IOS
software. Also, if you have updated the software since you purchased the router.
it may bean older version of Cisco IOS software,
Boot system flash “name”
Boot from a Server
Boot from a ROM
First step when preparing to copying between TFTP and Flash
Preparing For TFTP
Copying software between the TFTP host and Flash memory in the router. However,
before you do this, you must prepare for the TF server by checking the following
preliminary conditions:
• On the router, check to make sure that you can see and write into Flash memory.
Verify that the router has sufficient room in Flash memory to accommodate the
Cisco IOS software image.
• From the router, check to make sure that you can access the TFTP server over
the TCP/IP network. The ping command is one method that can help you check
this.
• On the TFTP server, check to make sure you know the file or file space for the
Cisco IOS software image. For upload and download operations, you need to
specify a path or filename.
If there is insufficient free memory, you will not be able to copy
or load the image, which means that you can either try to obtain a
smaller Cisco IOS software image or increase the available
memory on the router.
The naming convention for Cisco IOS Release 11.2 contains three parts:
1. the platform on which the image runs (cpa25)
2. a letter or series of letters identifies the special capabilities and feature sets
supported in the image ( cg )
3. specifies where the image runs and whether it has been zipped, or
compressed
One reason for this upload to the server would be to provide a fallback copy of
the current image prior to updating the image with a new version. Then, if
problems develop with the new version, the administrator can download the
backed-up image and return to the image that was running before the update
attempt.
copy flash tftp -- send image to server
show flash --- to view name of system image file
After you have provided for a backup copy of the current Cisco IOS
software image, you can load a new image.
You download the new image from the TFTP server by using the
command copy tftp flash.
Configuration register for password recovery for a 2500 router? --
0x2142
Command to configure a Ethernet port? --
•Router (config)# int E0 ip address subnet mask
•Routing Protocol -- Router(config)# router rip
8.1.2.1. Make a
flowchart
showing the
router
configuration
process.
8.1.3.1. Describe and perform
the router password recovery
procedure on 1600 and 2500
series routers.