CCNA 2 v3.1 Module 5

Module 5 Managing IOS Software CCNA 2 Module 5 Managing IOS Software

Router Boot Sequence and Verification

Stages of the router power-on boot sequence Cisco Router cannot operation without CISCO Internetwork Operating System (IOS) The startup routines must do the following: Test the router hardware Find and load the Cisco IOS software Find and apply configuration statements Including protocol functions and interface addresses

The sequence: Try the interactive media CCNA 2 Module 5 Page 5.1.1

How a device locates and loads IOS Normally the router looks to the NVRAM Router can use fallback sequence to load the software Search for boot system commands in NVRAM If boot system commands are not found Search FLASH for IOS Search for TFTP Server with IOS Limited IOS from ROM Configuration register enable alternatives Try interactive media lab CCNA 2 Module 5 Page 5.1.2

Configuration Register Saved in NVRAM Identify where to boot the IOS image from To set the configuration register manually Router#config terminal Router(config)#boot system flash ios-filename Router(config)#boot system tftp ios-filename tftp-address Router(config)#boot system ROM

To manually boot IOS from Flash Advantage of booting from FLASH Information is not vulnerable to network failures that can occur when loading system images from TFTP servers Steps Router#config terminal Router(config)#boot sytem flash gsnew-image Router(config)#Ctrl-Z Router#copy running-config startup-config

TFTP Network Server Used in case flash memory becomes corrupted Steps Router#config terminal Router(config)#boot system tftp IOS_image 172.16.13.111 Router(config)#Ctrl-Z Router#Copy running-config startup-config

ROM Used when System image in ROM Software may be an older version Flash memory is corrupted And Network server fails to load the image System image in ROM Is a subset of the Cisco IOS Lacks protocols, features and configurations of the full Cisco IOS Software may be an older version Steps router#config t Router(config)#boot system rom Router(config)#Ctrl-Z Router#copy run start

Configuration register 16-bit register in NVRAM The lowest four bits is for the boot field To find the current configuration register values Router#show version To change the boot field in configuration register Use config register command

To set to ROM monitor mode Note When I use nnn it means use the numbers identified when using show version To set to ROM monitor mode Router#config t Router(config)#config register 0Xnnn0 Boot from ROM Router(config)#config register 0Xnnn1 Examine NVRAM for boot system Router(config)#config register 0Xnnn2 to F 2 represents boot from Flash Try interactive lab CCNA 2 Module 5 Page 5.1.4

Troubleshooting IOS boot failure What could be wrong if the Router does not boot: Configuration file has missing or incorrect boot system statement Incorrect configuration register value Corrupted flash image Hardware failure

How to identify problems An incorrect configuration register setting will prevent the IOS from loading from flash Confirm this using show version Correct this by changing the configuration register in the configuration and saving this as the start-up configuration Corrupted flash image file Error message 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

Managing the CISCO File System

Files in Memory Operating system files - IOS…MBs Configuration files - …KBs

Startup configuration (startup config) IOS Stored in Flash memory - non-volatile storage IOS can be upgraded or have multiple copies IOS is copied into RAM and run from RAM Startup configuration (startup config) Stored in Non-volatile RAM - NVRAM Copied into RAM at boot time Running Configuration (running config) Stored in RAM Used to operate the router Try interactive lab CCNA 2 Module 5 Page 5.2.1

IOS naming conventions

First part identifies the hardware platform Second part identifies the features the file contains Basic – A basic feature set for the hardware platform, e.g.IP Plus – Basic features ..IP/FW Plus, and Enterprise Plus Encryption – k8 > Less than or equal to 64-bit encryption in IOS version 12.2 and up k9 > Greater than 64-bit encryption (on 12.2 and up) Third part indicates the file format Is the IOS is stored in flash in a compressed format or not Is the IOS relocatable(can be copied into RAM) or not(run from flash) Fourth part identifies the release of the IOS Try interactive media lab CCNA 2 Module 5 Page 5.2.2

Managing configuration files using TFTP Your configuration file should be backed up on a TFTP server. Router#copy running-config tftp Enter the IP address of the TFTP server Enter the configuration file name or press enter to accept the default name Confirm the choices by typing yes each time

Retrieving or using TFTP config backup: Router#copy tftp running-config Select a host or network configuration file Enter the IP address of the TFTP server Enter configuration file name or press enter to accept the default name

Managing configuration files using copy and paste Another way to create a backup of the configuration Capture the output of show running-config Select the output in the HyperTerminal screen and paste it into a text file. Things that have to be deleted: show running-config Building configuration... Current configuration: - More - Any lines that appear after the word "End" Add comments Use an exclamation mark (!) at the beginning of the line

Note at the end of each of the interface Add the no shutdown command HyperTerminal can be used to restore a configuration. Erase the startup configuration file Router#erase startup-config Restart the router Router#reload Enter router global configuration mode Router#config t Transfer the configuration data From HyperTerminal, click on Transfer > Send Text File. Select the name of the file for the saved backup configuration Observe any errors Return to privilaged mode Ctrl-Z Save running configuration files to backup configuration Router#copy running-config startup-config

Managing IOS images using Xmodem If IOS image in flash is erased or corrupted Restore IOS from the ROM monitor mode (ROMmon) Reasons are a corrupt or missing image Examine flash with the dir flash: command If an image is located that appears to be valid, an attempt should be made to boot from that image.

rommon 1>boot flash:c2600-is-mz.121-5 Why would it boot correctly from ROM not flash? show version checks the configuration register to ensure that it is configured for the default boot sequence If configuration register is correct show startup-config See if there is a boot system command instructing the router to use the IOS for ROM monitor If router will not properly boot from the image or there is no IOS image Download a new IOS using Xmodem to restore the image through the console or TFTP from the ROMmon mode

Download using XModem from ROMmon To restore the IOS through the console PC needs a copy of the IOS file to restore and a terminal emulation program (HyperTerminal) The IOS can be restored using default console speed of 9600 bps baud rate can be changed to 115200 bps to speed up the download Use Xmodem in ROMmon to restore IOS software image from the PC Format xmodem -c image_file_name E.g., xmodem -c c2600-is-mz.122-10a.bin  -c instructs Xmodem to use Cyclic Redundancy Check (CRC) for error checking during the download

Environment variables Fasted way to download IOS image using TFTP from ROMmon ROMmon has very limited functions No configuration file loaded during boot Set environmental variables (set) IP_ADDRESS – The IP address on the LAN interface IP_SUBNET_MASK – The subnet mask for the LAN interface DEFAULT_GATEWAY – Default gateway for the LAN interface TFTP_SERVER – The IP address of the TFTP server TFTP_FILE – The IOS filename on the server Use the tftpdnld command When new image is written to flash restart router using i

File system verification Router#show version checks The current image The total amount of flash. The source of the IOS image the router used to boot and displays the configuration register Configuration register Determines where the router is to load the IOS from

Router#show flash command identifies IOS image(s) in flash The amount of flash memory Used to confirm that there is ample space to store a new IOS image