Managing a Cisco Router
Router Internals
Router Components
| Component |
Location |
Description |
| Bootstrap |
stored in microcode in ROM |
Boots router and loads IOS |
| P.O.S.T. |
stored in microcode in ROM |
Checks basic functionality of router hardware and determines which
interfaces are present |
| ROM Monitor |
stored in microcode in ROM |
Used for manufacturer testing and troubleshooting |
| Mini IOS |
stored in microcode in ROM |
Also called RXBOOT or bootloader, Small IOS in ROM can be used to bring up
an interface and load a Cisco IOS into flash memory |
| RAM |
hardware |
Holds packet buffers, routing tables, software and data structures that
allow the router to function. running-config is stored in RAM. IOS can be
run from here on some routers |
| ROM |
hardware |
Used to start and maintain the router |
| Flash memory |
hardware |
Used to store the IOS. Not erased when the router is reloaded. An EEPROM
chip. |
| NVRAM |
hardware |
Used to hold router or switch configuration. Not erased when the router or
switch is reloaded. (holds startup-config) usually 32K in size. |
| Configuration Register |
in NVRAM |
Controls how the router boots |
Backing Up and Restoring Cisco IOSs
Before upgrading or restoring an IOS, you should backup the current version
to a TFTP server. By default Flash memory is used to store the Cisco IOS.
Verify Flash
Router3>en
Router3#show flash
File Length Name/status
1 10218508 /c2500-js-l_120-8.bin
[10316471 bytes used, 6460745 available, 16777216 total]
16384K bytes of processor board System flash (Read ONLY)
The last line shows the amount of flash memory on board
(16384K bytes of processor board System flash)
Filename for this IOS is c2500-js-l_120-8.bin
| Filename Explained |
| c2500 |
Platform |
| j |
Enterprise image |
| s |
File contains extended capabilities |
| l |
Indicates file may be moved, not compressed |
| 120-8 |
Revision number |
| .bin |
Executable binary file |
Backup IOS
Use the show version command to determine the version of the IOS on
the router and the filename of the image, you already got the size of flash from
the previous command.
Router_1#show version
ROM: System Bootstrap, Version 12.0, RELEASE SOFTWARE
BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c)XB1,
RELEASE SOFTWARE (fc1)
Router_1 uptime is 11 minutes
System restarted by power-on
System image file is c2500-js-1_120-8.bin, booted via flash
Bridging software.
X.25 software, Version 3.0.0.
1 Ethernet/IEEE 802.3 interface(s)
2 Serial network interface(s)
32K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read ONLY)
Configuration register is 0x2102
Router_1#
Use the following command to copy the IOS from flash to a TFTP server:
Router3#copy flash tftp
System flash directory:
File Length Name/status
1 6078548 c2500-js-l_120-8.bin
[6078612 bytes used, 2309996 available, 8388608 total]
Address or name of remote host [255.255.255.255]? 192.168.1.70
Source file name? c2500-js-l_120-8.bin
Destination file name [c2500-js-l_120-8.bin]?
Verifying checksum for 'c2500-js-l_120-8.bin' (file # 1)... OK
Copy 'c2500-js-l_120-8.bin' from Flash to server
as 'c2500-js-l_120-8.bin'? [yes/no]yes
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[cut for brevity]
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Upload to server done
Flash copy took 0:01:44 [hh:mm:ss]
TFTP doesn't allow directory browsing or user authentication, so the file is
put in the default directory of the TFTP server.
Restoring or Upgrading the IOS
Restoring from a TFTP server.
Make sure that file is in the TFTP's default directory (you won't be prompted
for the directory from the TFTP server, you have to know where it is).
Router3#copy tftp flash
**** NOTICE ****
Flash load helper v1.0
This process will accept the copy options and then terminate
the current system image to use the ROM based image for the copy.
Routing functionality will not be available during that time.
If you are logged in via telnet, this connection will terminate.
Users with console access can see the results of the copy operation.
---- ******** ----
Proceed? [confirm]
The above tells you that the router must reboot.
System flash directory:
File Length Name/status
1 6078548 c2500-js-l_120-8.bin
[6078612 bytes used, 2309996 available, 8388608 total]
Address or name of remote host [192.168.1.70]? 192.168.1.70
If you've used a TFTP server before, it will use it as the default choice.
The next prompt is for the source filename, which must be in the TFTP's root
directory.
Source file name? c2500-js-l_120-8.bin
Destination file name [c2500-d-l_113-5.bin]?
Accessing file 'c2500-d-l_113-5.bin' on 192.168.1.70...
Loading 'c2500-js-l_120-8.bin' from 192.168.1.70 (via Ethernet0): ! [OK]
Next you are prompted three times to confirm that the current flash file will
be erased, you will be prompted to backup the running-config to startup-config
if it has been changed since the router will reboot.
Erase flash device before writing? [confirm]
Flash contains files. Are you sure you want to erase? [confirm]
System Configuration has been modified. Save? [yes/no]: yes
Building configuration...
[OK]
Copy 'c2500-js-l_120-8.bin' from server
as 'c2500-js-l_120-8.bin' into Flash WITH erase? [yes/no]yes
Router reboots and loads the Mini IOS from ROM in order to erase the flash
since the flash can't be erased while it's in use.
%SYS-5-RELOAD: Reload Requested
%FLH: c2500-js-l_120-8.bin from 192.168.1.70 to flash ...
System flash directory:
File Length Name/status
1 6078548 c2500-js-l_120-8.bin
[8121064 bytes used, 8656152 available, 16777216 total]
Accessing file 'c2500-js-l_120-8.bin' on 192.168.1.70...
Loading c2500-js-l_120-8.bin from 192.168.1.70 (via Ethernet0): ! [OK]
New file is copied
Erasing device... eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
eeeeeeeeeeeeeeeeeeeeee
Loading c2500-js-l_120-8.bin from 192.168.1.70 (via Ethernet0):
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[output cut for brevity]
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
After copy
[OK 10935532/16777216 bytes]
Verifying checksum... OK (0x2E3A)
Flash copy took 0:05:45 [hh:mm:ss]
%FLH: Re-booting system after download
Router reboots and new IOS is used
Reload the Router
After upgrading the IOS, you will have to reload the router to use the new
software. Note that some routers reboot automatically when you copy a new
version of software to the router if it doesn't, use the following command.
Router_2#reload
Proceed with reload? [confirm] yes
%SYS-5-RELOAD: Reload requested
Backing Up and Restoring System Configuration
Any changes made to the router configuration are stored in running-config,
copying the running-config to the startup-config in NVRAM will
ensure that changes made to the system configuration are saved in the event that
the router is reloaded. Use the following command to save configuration
changes.
Router#copy running-config startup-config
Building configuration...
[OK]
Router#
Copying running-config to TFTP
Copying the running-config to a TFTP server allows you to maintain a
second copy in the event that you make irreversible errors to running-config
and startup-config. Use the following command and answer the
questions such as server's IP address and destination filename.
Router_2#copy running-config tftp
Remote host []? 192.168.1.70
Name of configuration file to write [router-confg]? < Enter >
Write file router-confg on host 192.168.1.70? [confirm] < Enter >
Building configuration...
Writing router-confg !!!!!!!!!!!!!!!!!!!!!![OK]
Restoring Configuration Files
If you've made changes to the running-config, the easiest way to
undo all of the changes is to copy the startup-config to the
running-config. Providing, of course, that you haven't saved any of
the changes you want to get rid of. If you saved changes to the
startup-config, you can load a config file from a TFTP server as long as
you remembered to back it up before making changes.
From startup
To restore the startup-config file from NVRAM
to the running-config in RAM use the following
command and note that running-config will be
overwritten with the startup-config file
information.
Router3#copy startup-config runnning-config
From TFTP
You can also restore the running-config file
from a TFTP server, providing that you have backed it up
there.
Router_2#copy tftp running-config
Host or network configuration file [host]? < Enter >
Address of remote host [255.255.255.255]? 192.168.1.70
Name of configuration file [router-confg]? router-confg
Configure using router-confg from 192.168.1.70 [confirm]? < Enter >
Loading router-confg from 192.168.1.70 (via serial 0) !!!!!!
[OK - 882/32723]
Erasing the Configuration
Use the following command to erase the startup file and enter setup mode
whenever the router is reloaded.
Router_2#erase startup-config
|
No Prestudy