Bài giảng Mạng máy tính nâng cao - Chapter 03: Managing Cisco IOS software

Chapter03_MANAGING CISCO IOS SOFTWARE Mạng Máy Tính Nâng CaoObjective Identify the stages of the router boot sequence Determine how a Cisco device locates and loads the Cisco IOS Use the boot system command Identify the configuration register values Briefly describe the files used by the Cisco IOS and their functions List the locations on the router of the different file types Briefly describe the parts of the IOS name Save and restore configuration files using TFTP and copy-and-paste Load an IOS image using TFTP Load an IOS image using XModem Verify the file system using show commands Router Boot-up Process There are four major phases to the bootup process:Performing the POST (Power On Seft Test)Loading the bootstrap programLocating and loading the Cisco IOS softwareLocating and loading the startup configuration file or entering setup modeRouter Boot-up Process Router Boot-up ProcessRouter Boot-up ProcessVerify the router boot-up process: The show version command is used to view information about the router during the bootup process. Information includes:Platform model numberImage name & IOS versionBootstrap version stored in ROMImage file name & where it was loaded fromNumber & type of interfacesAmount of NVRAMAmount of flashConfiguration registerRouter Boot-up Process See moreLocating IOS Software Configuration register 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 global configuration mode command config-register. Use a hexadecimal number as the argument for this command Software Components In Memory Fields in the IOS Name See moreManaging conf. files using copy and paste To capture the configuration using the text displayed on the HyperTerminal screen to a text file: Select Transfer Select Capture Text Specify the name for the text file to capture the configuration Select Start to start capturing text Display the configuration to the screen by entering show running-config Press the space bar when each "-More -" prompt appears When the complete configuration has been displayed, stop the capture by: Select Transfer Select Capture Text Select Stop Managing conf. files using copy and paste Restore the configuration using the text file from the HyperTerminal software: Enter router global configuration mode. From HyperTerminal, click on Transfer > Send Text File. Select the name of the file for the saved backup configuration. The lines of the file will be entered into the router as if they were being typed. Observe any errors. After the configuration is entered, press Ctrl-Z key to exit global configuration mode. Restore the startup configuration with copy running-config startup-config. Managing IOS images using TFTP Managing IOS images using Xmodem If the IOS image in flash has been erased or corrupted, the IOS may need to be restored from the ROM monitor mode (ROMmon). To restore the IOS through the console, the local PC needs to have a copy of the IOS file to restore and a terminal emulation program such as HyperTerminal. The IOS can be restored using the default console speed of 9600 bps. The baud rate can be changed to 115200 bps. The console speed can be changed from ROMmon mode using the confreg command Managing IOS images using Xmodem xmodem -c image_file_name For example, to restore an IOS image file with the name “c2600-is-mz.122-10a.bin”:xmodem -c c2600-is-mz.122-10a.binIn HyperTerminal, select Transfer > Send File. Then in the Send File popup specify the image name/location, select Xmodem as the protocol, and start the transfer Before restarting the router, the console speed needs to be set back to 9600 and the config register back to 0x2102 by command config-register 0x2102 at the privileged EXEC prompt See moreEnvironment variables 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 tftpdnld command.The ROMmon TFTP transfer works only on the first LAN port so a simple set of IP parameters are set for this interface.Syntax : VARIABLE_NAME=value Note: All variable names are case sensitiveTo check the ROMmon environment variables, the set command can be used See moreList of Environment variables IP_ADDRESS – The IP address on the LAN interface IP_SUBNET_MASK – The subnet mask for the LAN interface DEFAULT_GATEWAY – The default gateway for the LAN interface TFTP_SERVER – The IP address of the TFTP server TFTP_FILE – The IOS filename on the server File system verification show version show flash