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Slide 1: CCNA – Semester2 Module 5 Managing Cisco IOS Software Objectives • Router boot sequence and verification • Identify the configuration register values • Save and restore configuration files • Save and restore IOS images
Slide 2: Router Boot Sequence and Verification Router Startup Sequence
Slide 3: Locating the Cisco IOS Software Boot IOS from Flash Memory • A system image from flash memory can be loaded. The advantage is that information stored in flash memory is not vulnerable to network failures.
Slide 4: Boot IOS from TFTP • In case flash memory becomes corrupted, a system image can be loaded from a TFTP server. Boot IOS from ROM • If flash memory is corrupted and the network server fails to load the image, booting from ROM (if available) is the final bootstrap option in software.
Slide 5: Configuration register • The order in which the router looks for system bootstrap information depends on the boot field setting in the configuration register. • The configuration register is a 16-bit register in NVRAM. Configuration register • Use a hexadecimal number to express configuration register value . 16-bit register 0x • • • • • • 0000 0000 0000 6 0000 3210 Bit: 16 0 – 3: 6: 8: 11-12: 13: 15: Boot field Ignore NVRAM contents Break disabled Console line speed Boot ROM if network boot fails Diagnostic and ignore NVRAM
Slide 6: Configuration register: Boot field (2) • Router(config)# config-register 0x2102 • Router(config)# exit • Router# show version show version Cisco Internetwork Operating System Software IOS (tm) 2500 Software (C2500-D-L), Version 12.0(10), RELEASE SOFTWARE (fc1) Copyright (c) 1986-2000 by cisco Systems, Inc. Compiled Mon 20-Mar-00 22:33 by phanguye Image text-base: 0x0303882C, data-base: 0x00001000 ROM: System Bootstrap, Version 11.0(10c), SOFTWARE BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWARE (fc1) SGCTT-HCM uptime is 1 week, 1 day, 1 hour, 9 minutes System restarted by power-on System image file is "flash:c2500-d-l.120-10" cisco 2500 (68030) processor (revision N) with 2048K/2048K bytes of memory. Processor board ID 23101339, with hardware revision 00000000 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
Slide 7: The router boot process ROM monitor initializes Stays in ROM monitor 0 What is Boot field? 1 Boots the image in boot ROM or boot flash 2 to F yes Executes boot commands no Router’s Fallback sequence Boot commands in NVRAM ? Password Recovery Start Cold Boot router Ctrl + Break Within 60s In 25xx routers o/r 0x2142 In 26xx routers confreg 0x2142 i
Slide 8: Password Recovery Initial Config? N enable Copy start run Conf term Enable secret cisco Password Recovery Config-register 0x2102 Ctrl-Z Copy Run Start
Slide 9: Troubleshooting IOS boot failure • In the event that the router does not boot properly, there are several things that could be wrong: – – – – Configuration file has missing or incorrect boot system statement Incorrect configuration register value Corrupted flash image Hardware failure Incorrect Boot System Statement • Use the show running-config command and look for a boot system statement near the top of the configuration. • If the boot system statement points to an incorrect IOS image, delete the statement using the “no” version of the command.
Slide 10: Incorrect configuration register value • An incorrect configuration register setting will prevent the IOS from loading from flash. • The value in the configuration register tells the router where to get the IOS. • This can be confirmed by using the show version command Corrupted flash image • If this is the case, an error message should be displayed during boot. That message may take one of several forms. 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.
Slide 11: Hardware failure • If none of the above appears to be the problem, the router could have a hardware failure. • If this is the case, the Cisco Technical Assistance (TAC) center should be contacted. • Although hardware failures are rare, they do occur. Managing the Cisco File System
Slide 12: Software Components in Memory • Routers and switches depend on software for their operation. The two types of software required are operating systems and configuration files. Cisco IOS File System • Beginning with version 12 of the IOS, a single interface to all the file systems that a router uses is provided. This is referred to as the Cisco IOS File System (IFS). • The IFS provides a single method to perform all the file system management that a router uses. • This would include the flash memory file systems, the network file systems (TFTP, rcp, and FTP), and reading or writing data (such as NVRAM, the running configuration, ROM).
Slide 13: IOS Version 12.x commands • The IFS uses the URL convention to specify files on network devices and the network. The URL convention identifies the location of the configuration files following the colon as [[[//location]/directory] /filename] • IOS naming conventions
Slide 14: Managing configuration files using TFTP Managing configuration files using copy and paste • Another way to create a backup copy of the configuration is to capture the output of the show running-config command • Input configuration file using eather Hyper Terminal-Send Text or Windows Buffer (Copy and Paste)
Slide 15: Managing IOS images using TFTP Environment variables • The environmental variables provide a minimal configuration to allow for the TFTP of the IOS. • The ROMmon TFTP transfer works only on the first LAN port so a simple set of IP parameters are set for this interface.
Slide 16: Setting environment variables • Start router and press Ctrl+Break • Configure the environment variables – – – – – – – – – IP_ADDRESS= {ip_address} IP_SUBNET_MASK={ip_subnet_mask} DEFAULT_GATEWAY={default_gateway} TFTP_SERVER={tftpserver_ip_address} TFTP_FILE={IOS_filename} set sync (save environment variables in NVRAM) tftpdnld reset (after download completed) Summary • • • • Identifying stages of the router boot sequence Using the boot system command Identifying the configuration register settings Managing configuration files using copy-andpaste • Managing system files with TFTP
Slide 17: CCNA2 – Module5