ROUTER MAINTENANCE AND ADMINISTRATION

 1- Using the boot system command:

The following three examples demonstrate the use of several boot system commands to specify the Cisco IOS software rescue boot sequence.

2-Network server 

If the flash memory is damaged, a system image can be loaded from a TFTP server.

3-ROM 

If the flash memory is damaged and the network server fails to load the image, booting from the ROM is the software's last bootstrap option.  The system image stored in ROM contains some line command

The copy running-config startup-config command saves commands to NVRAM. The router will execute, if necessary, boot system commands in the order in which they were initially entered into configuration mode

4-Troubleshooting an iOS boot failure:

There are several things that can cause a router to boot poorly: 

the configuration file has a missing or incorrect boot system statement. 

 A value in the configuration registry is incorrect. 

 the flash image is corrupted, 

 hardware failure. 

5-Managing configuration files using TFTP:

In a Cisco router, the configuration is loaded into RAM and the boot configuration is stored in NVRAM by default. To prevent possible loss of configuration, this boot configuration must be backed up. One of the backup copies of the configuration can be stored on a TFTP server. The copy running-config tftp command can be used for this. The steps in this process are listed below: 

-Enter the copy running-config tftp command. 

-When prompted, enter the IP address of the TFTP server to store the configuration file. 

-Enter the name you want to give the configuration file or accept the default name. 

-Confirm the choices by typing yes each time. 

The router configuration can be restored by loading the configuration backup file from a TFTP server. The following steps describe this process:

1-Enter the copy tftp running-config command. 

2- When prompted, select a host or network configuration file. 

3-At the system prompt, type the IP address of the TFTP server where the configuration file is located. 

4- At the system prompt, enter the name of the configuration file or accept the default name. 

 Confirm the configuration file name and server address provided by the system .

6-Errors identified at layer 1 can be as follows:    

Broken cables 

Disconnected cables 

Cables connected to inappropriate ports 

Unstable connections 

Cables inappropriate for the task at hand (console cables, crossover cables and straight cables must be used wisely) 

Transceiver problems 

DCE wiring problems 

DTE wiring problems 

Units off 

7-Errors identified at layer 2 can include the following: 

   

Misconfigured serial interfaces 

Incorrectly configured Ethernet interfaces 

Inappropriate encapsulation assembly (HDLC is used by default for serial interfaces) 

Clock Frequency problem  

Network adapter issues 

8-Errors identified at layer 3 level may include:  

  

Routing protocol not enabled 

Invalid routing protocol enabled 

Incorrect IP addresses 

Incorrect subnet masks 

9- Reset password

 This procedure has the advantage of not overwriting the configuration, simply changing the passwords while keeping the existing configuration. The connection must be made by a console cable.

 You must then restart the router with the switch and press the CTRL key and "Pause" or "Break" on the keyboard within 30 seconds after booting. The following screen should then appear:

After rebooting the router asks if you want to enter the SETUP mode, answer "no" to this question.

The next step is to enter the privileged mode with this "blank" configuration.

No password configuration is blank