Tài liệu học CCNA kỳ 2 mod5 ManagingIOS

1 Module 5 – Managing Cisco IOS Software NIIT-ICT Hanoi info@niithanoi.vn 2 Overview • 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 2 NIIT-ICT Hanoi info@niithanoi.vn 3 Stages of the router power-on boot sequence • Test the router hardware. • Find and load the Cisco IOS software. • Find and apply configuration statements, including protocol functions and interface addresses. NIIT-ICT Hanoi info@niithanoi.vn 4 1. ROM 1. POST 2. Bootstrap code executed 3. Check Configuration Register value (NVRAM) Forth Hex : 0 = ROM Monitor mode 1 = ROM IOS 2 - 15 = startup-config in NVRAM 2. Check for IOS boot system commands in startup-config file (NVRAM) If boot system commands in startup-config a. Run boot system commands in order they appear in startup-config to locate the IOS b If boot system commands fail, use default fallback sequence to locate the IOS (Flash, TFTP, ROM) 3. Locate and load IOS, Default fallback sequence: No IOS boot system commands in startup-config a. Flash (sequential) b. TFTP server (netboot) - The router uses the configuration register value to form a filename from which to boot a default system image stored on a network server. c. ROM (partial IOS) or keep retrying TFTP depending upon router model - If no IOS located, get partial IOS version from ROM 4. Locate and load startup-config a. If startup-config found, copy to running-config b. If startup-config not found, prompt for setup-mode c. If setup-mode bypassed, create a “skeleton” default running-config (no startup-config) Router Boot Process – At a Glance 1, 2 3 4 3 NIIT-ICT Hanoi info@niithanoi.vn 5 2. Check for IOS boot system commands in startup- config file (NVRAM) NIIT-ICT Hanoi info@niithanoi.vn 6 Configuration register Check Configuration Register value (NVRAM) 0 = ROM Monitor mode 1 = ROM IOS 2 - 15 = startup-config in NVRAM • 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. • The lowest four bits of the configuration register form the boot field. • To ensure that the upper 12 bits are not changed, first retrieve the current values of the configuration register using the show version command. • Then use the config-register command, changing only the value of the last hexadecimal digit. 4 NIIT-ICT Hanoi info@niithanoi.vn 7 show version – Showing the configuration register Gateway-Router>show version Cisco Internetwork Operating System Software IOS (tm) C2600 Software (C2600-DO3S-M), Version 12.0(5)T1, RELEASE SOFTWARE (fc 1) Copyright (c) 1986-1999 by cisco Systems, Inc. Compiled Tue 17-Aug-99 13:18 by cmong Image text-base: 0x80008088, data-base: 0x80CB67B0 ROM: System Bootstrap, Version 11.3(2)XA4, RELEASE SOFTWARE (fc1) NoSmo-Gateway uptime is 5 weeks, 3 days, 20 hours, 33 minutes System returned to ROM by power-on System restarted at 13:30:22 PST Thu Mar 7 2002 System image file is "flash:c2600-do3s-mz.120-5.T1" cisco 2621 (MPC860) processor (revision 0x102) with 39936K/9216K bytes of memory . Processor board ID JAB03520113 (2485375272) M860 processor: part number 0, mask 49 Bridging software. X.25 software, Version 3.0.0. 2 FastEthernet/IEEE 802.3 interface(s) 4 Serial(sync/async) network interface(s) 32K bytes of non-volatile configuration memory. More— Configuration register is 0x2102 Gateway-Router> IOS source configuration register NIIT-ICT Hanoi info@niithanoi.vn 8 Modifying the configuration register To change the boot field in the configuration register, follow these guidelines: • To enter the ROM monitor mode, set the configuration register value to 0xnnn0, where nnn represents the previous value of the non-boot field digits. This value sets the boot field bits to 0000 binary. From ROM monitor, boot the operating system manually by using the b command at the ROM monitor prompt. • To configure the system to boot automatically from ROM, set the configuration register to 0xnnn1, where nnn represents the previous value of the non-boot field digits. This value sets the boot field bits to 0001 binary. • To configure the system to use the boot system commands in NVRAM, set the configuration register to any value from 0xnnn2 to 0xnnnF, where nnn represents the previous value of the non-boot field digits. These values set the boot field bits to a value between 0010 and 1111 binary. Using boot system commands in NVRAM is the default. Router(config)#config-register value 5 NIIT-ICT Hanoi info@niithanoi.vn 9 IOS file system overview RAM IOS (running) running-config startup-config IOS ios • Routers and switches depend on software for their operation. • The two types of software required are operating systems and configuration. – The operating system used in almost all Cisco devices is the Cisco Internetwork Operating System (IOS). – The software a router or switch uses is referred to as the configuration file or the config, running-config and startup-config. NIIT-ICT Hanoi info@niithanoi.vn 10 Cisco IOS File System (IFS) • Beginning with version 12.0 of the IOS, a single interface to all the file systems that a router uses is provided, Cisco IOS File System (IFS). • The IFS provides a single method to perform all the file system management that a router uses, including – the flash memory file systems, – the network file systems (TFTP, rcp, and FTP) – reading or writing data (such as NVRAM, the running configuration, ROM). RAM IOS (running) running-config startup-config IOS ios 6 NIIT-ICT Hanoi info@niithanoi.vn 11 Preparing for TFTP Be sure you can communicate with the TFTP server. Know the name of the IOS file you are going to copy from on the router. NIIT-ICT Hanoi info@niithanoi.vn 12 Cisco Traditional Copy Commands RAM IOS (running) running-config startup-config IOS ios copy tftp running-config copy tftp startup-config copy running-config tftp copy startup-config tftp copy from-file to-file copy flash tftp copy tftp flash 7 NIIT-ICT Hanoi info@niithanoi.vn 13 IOS naming conventions Examples of feature-set categories are: • Basic – A basic feature set for the hardware platform, for example IP and IP/FW • Plus – A basic feature set plus additional features such as IP Plus, IP/FW Plus, and Enterprise Plus • Encryption – The addition of the 56-bit data encryption feature sets, such as Plus 56, to either a basic or plus feature set. Examples include IP/ATM PLUS IPSEC 56 or Enterprise Plus 56. From Cisco IOS Release 12.2 onwards, the encryption designators are k8/k9: • 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) A relocatable image is copied from flash into RAM to run. A non- relocatable image is run directly from flash. NIIT-ICT Hanoi info@niithanoi.vn 14 Example 8 NIIT-ICT Hanoi info@niithanoi.vn 15 Managing configuration files using TFTP NIIT-ICT Hanoi info@niithanoi.vn 16 Managing configuration files using copy and paste Perform the following to capture the configuration using the text displayed on the HyperTerminal screen to a text file: 1. Select Transfer 2. Select Capture Text 3. Specify the name for the text file to capture the configuration 4. Select Start to start capturing text 5. Display the configuration to the screen by entering show running-config 6. Press the space bar when each "- More -" prompt appears 7. When the complete configuration has been displayed, stop the capture by: 8. Select Transfer 9. Select Capture Text 10. Select Stop 9 NIIT-ICT Hanoi info@niithanoi.vn 17 Managing IOS images using TFTP NIIT-ICT Hanoi info@niithanoi.vn 18 Restoring the IOS image from Flash • If the IOS image in flash has been erased or corrupted, the IOS may need to be restored from the ROM monitor mode (ROMmon). 1. ROM 1. POST 2. Bootstrap code executed 3. Check Configuration Register value (NVRAM) 0 = ROM Monitor mode 1 = ROM IOS 2 - 15 = startup-config in NVRAM • In many of the Cisco hardware architectures, the ROMmon mode is identified from the rommon 1 > prompt. • The flash should be examined with the rommon 1 > dir flash: command. • If an image is located that appears to be valid, an attempt should be made to boot from that image. • This is done using boot flash: command. rommon 1>boot flash:c2600-is-mz.121-5 10 NIIT-ICT Hanoi info@niithanoi.vn 19 Restoring the IOS image from Flash RAM IOS (running) running-config startup-config IOS ios • If the router properly boots, determine why the router booted to the ROMmon instead of using IOS from flash. – show version - to check the configuration register to ensure that it is configured for the default boot sequence – show startup-config - to see if there is a boot system command instructing the router to use the IOS for ROM monitor. • If the router will not properly boot from the image or there is no IOS image, a new IOS will need to be downloaded. – The IOS file may be recovered using either: • Xmodem to restore the image through the console • Downloading the image using TFTP from the ROMmon mode. NIIT-ICT Hanoi info@niithanoi.vn 20 Download using Xmodem from ROMmon • Optional – Modifying the console baud rate to speed-up upload. • Requires rebooting of the router and the terminal session (at 9600) should be terminated and a new session started at 115200 bps to match the console speed. console [...]... 0x10EA82C (PC) rommon> NIIT-ICT Hanoi info@niithanoi.vn 27 Password Recovery Step 3 Breaking in - For the 26 00 Series routers, after the “rommon>” prompt type confreg 0x21 42 and press return Then type “boot” and press return Abort at 0x10EA82C (PC) rommon> confreg 0x21 42 rommon> boot • confreg 0x21 42 – This will change the configuration register on the router to ignore the startup-config file during boot-up... info@niithanoi.vn 24 12 Download using TFTP from ROMmon • Once the variables are set for the IOS download, the tftpdnld command is entered with no arguments NIIT-ICT Hanoi info@niithanoi.vn 25 File system verification NIIT-ICT Hanoi info@niithanoi.vn 26 13 Password Recovery Step 1 config-register - At the router type the show version command Record the configuration register setting, which is usually 0x21 02 In... perform this step Step 2 – Entering rommon Within 60 seconds press the Break key (control-break on a PC) You may need to press this more than once You will then see the following prompt: System Bootstrap, Version 5 .2( 8a), RELEASE SOFTWARE Copyright (c) 1986-1995 by cisco Systems 26 00 processor with 81 92 Kbytes of main memory Abort at 0x10EA82C (PC) rommon> NIIT-ICT Hanoi info@niithanoi.vn 27 Password Recovery... info@niithanoi.vn 22 11 Download using Xmodem from ROMmon Router(config)#config-register 0x21 02 Router(config)#line con 0 Router(config-line)#speed 9600 console • • • Once the transfer is complete a message appears that flash is being erased This is followed by the “Download Complete!” message Before restarting the router, the console speed needs to be set back to 9600 and the config register back to 0x21 02 • Enter... this? Router(config)# config-register 0x21 02 Router(config)# exit Copy the running-config with the current privileged password to the startup-config Router# copy running-config startup-config NIIT-ICT Hanoi info@niithanoi.vn 29 Password Recovery Step 5 – Verify • At the router type the show version command • The configuration register setting should be 0x21 02 NIIT-ICT Hanoi info@niithanoi.vn 30 15... speed needs to be set back to 9600 and the config register back to 0x21 02 • Enter the command config-register 0x21 02 at the privileged EXEC prompt • While the router is rebooting, the 11 520 0 bps terminal session needs to be ended and a 9600 bps session begun NIIT-ICT Hanoi info@niithanoi.vn 23 Download using TFTP from ROMmon • The IOS can also be restored from a TFTP session using the tftpdnld command... ignore the startup-config file during boot-up • boot – This will reboot (reload) the router The router will reboot and ask you if you want to go into setup mode Type no NIIT-ICT Hanoi info@niithanoi.vn 28 14 Password Recovery Step 4 – Recovering the password Router> enable Router# config t To recover your previous startup-config file so you do not lose your previous configuration (if needed): Router#... The format of the command is: xmodem -c image_file_name The -c instructs the Xmodem process to use Cyclic Redundancy Check (CRC) for error checking during the download NIIT-ICT Hanoi info@niithanoi.vn 21 Download using Xmodem from ROMmon console • • • • • • The router will prompt not to begin the transfer and present a warning message The warning message informs that the bootflash will be erased and