3584K/512K bytes of memory. This line shows how much main and shared memory is installed in the router. Some platforms use a fraction of DRAM as shared memory. The memory requirements take this into account, so both numbers have to be added together to find the amount of DRAM installed on the router. To find out the amount of flash memory, issue the show flash command: GAD#show flash
… <output omitted>…
15998976 bytes total (10889728 bytes free)
Content 2.1 Operating Cisco IOS Software 2.1.5 Operation of Cisco IOS Software The Cisco IOS devices have three distinct operating environments or modes: The startup process of the router normally loads into RAM and executes one of these operating environments. The configuration register setting can be used by the system administrator to control the default start up mode for the router. The ROM monitor performs the bootstrap process and provides low-level functionality and diagnostics. It is used to recover from system failures and to recover a lost password. The ROM monitor cannot be accessed through any of the network interfaces. It can only be accessed by way of a direct, physical connection through the console port. When the router is running in boot ROM mode, only a limited subset of the Cisco IOS feature set is available. Boot ROM allows write operations to flash memory and is used primarily to replace the Cisco IOS image that is stored in flash. The Cisco IOS image can be modified in boot ROM by using the copy tftp flash command, which copies an IOS image stored on a TFTP server into the flash memory of the router. The normal operation of a router requires use of the full Cisco IOS image as stored in flash. In some devices, the IOS is executed directly from flash. However, most Cisco routers require a copy of the IOS to be loaded into RAM and also executed from RAM. Some IOS images are stored in flash in a compressed format and have to be expanded when copied to RAM. To see the IOS image and version that is running, use the show version command, which also indicates the configuration register setting. The show flash command is used to verify that the system has sufficient memory to load a new Cisco IOS image. Lab Activity e-Lab Activity: Operation of the Cisco IOS This lab demonstrates how to put a new Cisco IOS image onto the router. Web Links Cisco IOS Technologies http://www.cisco.com/warp/ public/732/Tech/
Content 2.2 Starting a Router 2.2.1 Initial startup of Cisco routers A router initializes by loading the bootstrap, the operating system, and a configuration file. If the router cannot find a configuration file, it enters setup mode. Upon completion of the setup mode a backup copy of the configuration file may be saved to nonvolatile RAM (NVRAM). The goal of the startup routines for Cisco IOS software is to start the router operations. To do this, the startup routines must accomplish the following: When a Cisco router powers up, it performs a power-on self test (POST). During this self test, the router executes diagnostics from ROM on all hardware modules. These diagnostics verify the basic operation of the CPU, memory, and network interface ports. After verifying the hardware functions, the router proceeds with software initialization. After the POST, the following events occur as the router initializes: Step 1 The generic bootstrap loader in ROM executes. A bootstrap is a simple set of instructions that tests hardware and initializes the IOS for operation. Step 2 The IOS can be found in several places. The boot field of the configuration register determines the location to be used in loading the IOS. If the boot field indicates a flash or network load, boot system commands in the configuration file indicate the exact name and location of the image. Step 3 The operating system image is loaded. When the IOS is loaded and operational, a listing of the available hardware and software components is output to the console terminal screen. Step 4 The configuration file saved in NVRAM is loaded into main memory and executed one line at a time. The configuration commands start routing processes, supply addresses for interfaces, and define other operating characteristics of the router. Step 5 If no valid configuration file exists in NVRAM, the operating system searches for an available TFTP server. If no TFTP server is found, the setup dialog is initiated. Setup is not intended as the mode for entering complex protocol features in the router. The purpose of the setup mode is to permit the administrator to install a minimal configuration for a router, unable to locate a configuration from another source. In the setup mode, default answers appear in square brackets [ ] following the question. Press the Enter key to use these defaults. During the setup process, Ctrl-C can be pressed at any time to terminate the process. When setup is terminated using Ctrl-C, all interfaces will be administratively shutdown. When the configuration process is completed in setup mode, the following options will be displayed: [0] Go to the IOS command prompt without saving this config.
[1] Return back to the setup without saving this config.
[2] Save this configuration to nvram and exit.
Enter your selection [2]: Lab Activity Lab Exercise: Router Configuration Using Setup In this lab the students will use the System Configuration Dialog (setup) to establish some basic router configuration. Web Links The Typical Boot Process http://csc.colstate.edu/summers/ NOTES/CS458/ chap11/tsld051.htm
Content 2.2 Starting a Router 2.2.2 Router LED indicators Cisco routers use LED indicators to provide status information. Depending upon the Cisco router model, the LED indicators will vary.An interface LED indicates the activity of the corresponding interface. If an LED is off when the interface is active and the interface is correctly connected, a problem may be indicated. If an interface is extremely busy, its LED will always be on. The green OK LED to the right of the AUX port will be on after the system initializes correctly. Web Links Reading the LEDs http://www.cisco.com/en/US/products/ hw/routers/ps259/products_installation_ guide_chapter09186a008007e022.html#34028
Content 2.2 Starting a Router 2.2.3 Examining the initial router bootup The examples in Figures - show information and messages displayed during initial bootup. This information will vary, depending on the interfaces in the router and the Cisco IOS release. The screens displayed in this graphic are for reference only and may not exactly reflect what the screen displays on the console. In Figure , the statement “NVRAM invalid, possibly due to write erase”, tells the user that this router has not been configured yet or that the NVRAM has been erased. A router must be configured, the configuration file saved to NVRAM, and then configured to use the NVRAM configuration file. The factory-default setting for the configuration register is 0x2102, which indicates that the router should attempt to load a Cisco IOS image from flash memory. In Figure , the user can determine the bootstrap version and the IOS version the router is using as well as the router model, processor, and the amount of memory the router contains. Other information listed in this graphic includes: In Figure , the user has the option to enter setup mode. Remember, the primary purpose of the setup mode is to permit the administrator to install a minimal