Distance Vector Routing Protocols
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CCNA 2 v3 – Module 5
Find and load the Cisco IOS software into RAM
Cisco Internetwork Operating System
Boot system flash c4500-p-mz_111-18.bin
The router uses boot system commands saved in NVRAM to locate the IOS.
Different settings in the configuration register enable the several alternatives:
Boot system tftp c4500-1.bin 192.168.1.7
Boot system rom
copy running-config startup-config
After it is reloaded, the router will try these commands in the order they were entered.
The order in which the router looks for system bootstrap information depends on the boot field setting in the configuration register. The default configuration register setting can be changed with the following command:
The lowest four bits of the configuration register form the boot field.
Configuration register is 0x2102Configuration Register – Boot Field
Configuration register is 0x2102
To view the current values of the configuration register:
The configuration register is a 16-bit register in NVRAM.
Note: the notation 0x informs us that the following number is a hexadecimal number.
From the example, Hex 2142 is 0010.0001.0000.0010 in binary.
Enter ROM monitor mode on reload.
Boot automatically from ROM.
Use boot system commands in NVRAM, this is the default.
0x2142: the system will not load the configuration file.
On boot the router checks the configuration file for a boot system statement.
Boot problems are typically caused by any of the following:
To identify the boot image source:
Cisco Internetwork Operating System Software
IOS (tm) C2600 Software (C2600-D-M), Version 12.2(16a), RELEASE SOFTWARE (fc2) ..<output omitted>..
ROM: System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1) Router uptime is 1 minute
System returned to ROM by power-on
System image file is "flash:c2600-d-mz.122-16a.bin"
If the router has a corrupted flash image file an error message should be displayed during boot.
Some examples are:
open: read error...requested 0x4 bytes, got 0x0
trouble reading device magic number
boot: cannot open "flash:"
boot: cannot determine first file name on device "flash:"ú
If the flash image is corrupt, a new IOS should be uploaded into the router.
The router could have a hardware failure.
If so, the Cisco TAC should be contacted.
operating systemIOS File System Overview
route or switch
Cisco IOS File System
Located in Flash
IOS Version numberIOS Naming Convention
System image file is "flash:c2600-d-mz.122-16a.bin"
The file format specifies if the IOS is compressed in flash and if the IOS is relocatable.
A relocatable image is copied from flash into RAM to run.
A non-relocatable image is run directly from flash.
As Cisco develops newer versions of the IOS, the numerical version number increases.
5.2.3 _____________. LabManaging configuration files using TFTP
My# copy running-config tftp
Remote host ? 18.104.22.168
Name of configuration file to write[my-config]? My2
Write file My2 to 22.214.171.124 ? [confirm] y
To store the current configuration on a network TFTP server enter the following command:
A configuration file stored on one of the network servers can be used to configure a router:
Router# copy tftp running-config
Host or network configuration file [host]?
IP address of remote host[255.255.255.255]? 10.0.0.13
Name of configuration file [Router-config] ? My2
Configure using My2 from 10.0.0.13? [confirm] y
Booting My2 from 10.0.0.13:
!!!!!! [OK-180/16000 bytes]
To capture the configuration from HyperTerminal to a text file:
Now all that appears on the screen will be written to the text file.
After the capture is complete, the configuration file needs to be edited to remove extra text, to add commands or to add comments with a !.
HyperTerminal can be used to restore a configuration. The edited backup of the configuration can be copied into the router:
5.2.5 _____________. LabManaging IOS Images using TFTP
Occasionally the router will need to have the IOS upgraded or restored. On a new router the IOS should be backed up.
copy tftp flash
Address or name of remote host ?
Source filename ?
Destination filename [c2600-d-mz.122-16a.bin]?
Erase Flash: before copying? [confirm]
Erasing the flash file system will remove all files
Loading c2600-d-mz.122-16a.bin from 192.168.1.17 (via FastEthernet 0/0):
.. .. .. ..OK
[OK 8906598 bytes]
8906598 bytes copied in 270.12 secs
Recovering IOS Images _____________.
To identify why the IOS image did not load from flash:
If the router will not properly boot from the image or there is no IOS image, a new IOS will need to be downloaded.
The IOS file may be recovered using either:
To restore the IOS through the console you need:
Changing the baud rate from 9600 bps to 115200 bps speeds up the download. To change console speed from rommon:
Console baud: 9600
Boot: the ROM Monitor
Do you wish to change the configuration? y/n [n]:
Enable diagnostic mode y/n [n]:
Change console baud rate? y/n [n]:
Enter rate: 0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400 4 = 19200, 5 = 38400, 6 = 57600, 7 = 115200 :
Note: After changing the console speed and restarting the router in rommon mode, the original terminal session at 9600 bps should be terminated and a new session started to match the 115200 bps console speed.
Use CRC _____________. for error checking during the download
Download using Xmodem from rommon >
The xmodem command can be used from the rommon mode to restore the IOS software image from the PC:
xmodem -c c2600-is-mz.122-10a.bin
Do not start sending program yet…
Warning: All existing data in bootflash will be lost!
Invoke this application only for disaster recovery.
Do you wish to continue? y/n [n]:
Ready to receive file c2600-is-mz.122-10a.bin . . .
Next, In HyperTerminal select Transfer > Send File.
Specify the image name/location
select Xmodem as the protocol
start the transfer.
During the transfer the Sending File popup will display the status of the transfer.
On completion, return config-register and HyperTerminal settings to normal.
Downloading the image using TFTP from rommon is the fastest way to restore an IOS image to the router. This is done by setting environmental variables and then using the tftpdnldcommand:
Receiving GAD/basic0204/c2600-I-mz.12-1.bin from 192.168.1.1
File reception completed