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CCNA 2 v3. 1 Module 2

CCNA 2 v3. 1 Module 2. CCNA 2. Module 2 Introduction to Routers. Cisco IOS. Cisco Internetwork Operating System is the software that controls routing and switching functions of internetworking devices Network services provided by Cisco IOS : Basic routing and switching functions

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CCNA 2 v3. 1 Module 2

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  1. CCNA 2 v3.1 Module 2

  2. CCNA 2 Module 2 Introduction to Routers

  3. Cisco IOS • Cisco Internetwork Operating System is the software that controls routing and switching functions of internetworking devices • Network services provided by Cisco IOS : • Basic routing and switching functions • Reliable and secure access to networked resources • Network scalability

  4. User Router Interface • Cisco IOS software uses a command-line interface (CLI) • This environment is accessible through several methods. • Console session • Uses a low speed serial connection directly from a computer or terminal to the console connection on the router • No initial configuration necessary

  5. Dialup connection: • Using a modem or null modem connected to the router AUX port. • No initial configuration necessary • Telnet session: • At least one interface must be configured with an IP address, and virtual terminal sessions must be configured for login and passwords.

  6. Router user interface modes • CLI uses a hierarchical structure. • Entry into different modes to accomplish tasks • E.g., To configure a router interface, the user must enter interface configuration mode. • Command executive (EXEC): Validates and executes the entered commands.

  7. IOS software separates the EXEC sessions into two access levels: • User EXEC mode • Privileged EXEC mode (enable) • User EXEC mode (view only) • Limited number of basic monitoring commands • To check and view the router status • Cannot change the configuration of the router • Prompt >

  8. Privileged EXEC mode (enable mode) • Accesses all router commands • Configuration and management • To ensure authorized users access this mode • Configured it to require a password from the user before accessing it & User ID • Provides access to • Global configuration mode and others • Prompt #

  9. Type enable to enter privileged exec mode Type disable to enter privileged exec mode Entering a question mark (?) at the privileged EXEC level will reveal many more command options than those available at the user EXEC level.

  10. IOS Naming Conventions • Platform (Hardware): C1005 • Features: “b”, Appletalk 40 = 40 bit encryption • Format: F = Flash, M = RAM • Compression: Z = Zip compressed

  11. Consideration when selecting a new IOS image • Compatibility with the router flash and RAM memory • i.e., is there enough space • To find this information use show version • router#show version • Displays the amount of available RAM • …cisco 1721 (68380) processor (revision C) with 3584K/512K bytes of memory. • 3584k main memory • 512k shared memory • router#show flash • Displays the amount of flash memory • …15998976 bytes total (10889728 bytes free

  12. Operation of Cisco IOS Software • The startup process of the router normally loads into RAM and executes one of three operating environments/ modes. • ROM monitor • Boot ROM • Cisco IOS • Systems administrator uses the configuration register setting to control the default start up mode for the router

  13. ROM Monitor: • provides low-level functionality and diagnostics • used to • recover from system failures • recover a lost password • Can only be accessed by direct, physical connection through the console port • Prompt: ROMMON> • Boot ROM : • Prompt: Router(boot)> • Offers only limited IOS features • Used for flash image updates • copy tftp flash • copies an IOS image stored on a TFTP server into the flash memory of the router

  14. Cisco IOS • Normal operating mode • Usually stored in Flash but run from RAM • Prompt: router> • show version • Displays • IOS image and version • Configuration register setting • Amount of available RAM • show flash • Displays the amount of flash memory • Used to verify that the system has sufficient memory to load a new Cisco IOS image

  15. Initial startup of Cisco routers If the router cannot find a configuration file, it enters “setup mode”. It is a basic configuration

  16. Startup routines must accomplish 3 things • Make sure that the router hardware is tested and functional. • Find and load the Cisco IOS software • Flash, TFTP Server, ROM • Find and apply the startup configuration fileor enter the setup mode • NVRAM, TFTP Server, Console

  17. Router Startup Sequence • Powers up • Performs a power-on self test (POST) • Executes diagnostics from ROM to check all hardware modules • This verifies basic operation of CPU, memory, network interface ports • Software initialization • The boot field of the configuration register determines the location to be used in loading the IOS. • Flash (0X2102), TFTP Server, ROM • IOS Software is loaded • List of hardware and software is displayed on console screen • If valid configuration file exists • Configuration file from NVRAM is loaded into main memory • start routing processes, supply addresses for interfaces • If no valid configuration file exists • Operating system searches for TFTP server • If no TFTP server the setup dialog is initiated

  18. Setup Mode • Entered only if configuration file cannot be found in NVRAM or TFTP • Permits administrator to enter minimal router configurations • Default answers appear in [ ] • Press Enter to use these defaults • Press Ctrl-C at any time • to terminate the process(setup mode) • all interfaces will be administratively shutdown

  19. Router LED indicators • An interface LED indicates the activity of the corresponding interface. A green OK LED indicates system is initialized correctly

  20. Examining the initial router bootupOutput Output indicates a problem with the “NVRAM”. It could be “Write erased”

  21. Router Output Tells • Bootstrap version • IOS version the router • Router model • Processor • Number of interfaces • Types of interfaces • Amount of NVRAM • Amount of flash memory

  22. Logging into the router

  23. When entering the Privilaged exec mode if the password: prompt is displayed, enter the password that has been set • Password commands to access privileged EXEC mode • Router(config)# Enable password <password> • Not encrypted • Router(config)#Enable secret <password> • Encrypted • Cannot be the same as enable password • Takes precedence over enable password

  24. From the Privileged mode you can enter the “Global Mode” & can configure the following; • Interface • Subinterface • Line • Router • Route-map • To return to the privileged mode type Ctrl Z.

  25. Keyboard help in the router CLI • Typing a question mark (?) displays a handy list of available commands. (user or privileged modes)

  26. “?” can also be used to complete incomplete commands • Eg .. Setting the router clock

  27. The "^" symbol appears at the point in the command string where an incorrect command, keyword, or argument was entered.

  28. Enhanced editing commands “$” sign indicates that the command has scrolled onto the next line.

  29. Router command history The maximum number of commands held is 256.

  30. The show version command • show version command: • IOS version and descriptive information • Bootstrap ROM version • Boot ROM version • Router up time • Last restart method • System image file and location • Router platform • Configuration register setting

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