Basic Device Configuration
When you buy a switch or a router, it will always come in a default state. As a network admin, you need full management and control of the devices in the network.
You will need to configure switches and routers so that the network does exactly what is required and works the way you want it to.
Of course the default configuration will be in its simplest form and will not comply to the network’s requirements unless configured properly.
Switch Boot Sequence
When you power on a Cisco Switch it goes through whats called “The Switch Boot Sequence” which is split into 5 steps as follows:
| The Switch Boot Sequence |
|---|
| Step 1 (Power-On Self-Test / POST) |
| When powered on, the switch loads the Power-On Self-Test (POST) software which is stored in its ROM. This checks the CPU subsystem. It tests the CPU, DRAM, and the portion of the flash device that makes up the flash file system. |
| Step 2 (Loads the Bootloader) |
| After the POST is complete, the switch loads the boot loader software. The boot loader is a small program which is also stored in ROM. |
| Step 3 (CPU Initialization) |
| The boot loader performs low-level CPU initialization. It initializes the CPU registers, which control where physical memory is mapped, the quantity of memory, and the speed. |
| Step 4 (Flash File System Initialization) |
| The boot loader then initializes the flash file system on the device’s board. |
| Step 5 (Locate and Load IOS) |
| Finally, the boot loader locates and loads the default IOS operating system software image into the memory and gives control of the switch over to the IOS. |
Boot System Command
A switch will automatically attempt to boot by using the information in the BOOT environment variable. If this variable is not set, the switch then attempts to load and execute the first executable file it can find. On switches, this image file is normally found in a directory that has the same name as the image file (excluding the .bin ext).
After such image file is located, then the IOS initializes the interfaces using the IOS commands found in the startup-config file. The startup-config file is called config.text and is located in the flash.
Command to boot IOS manually
S1(config)# boot system flash:/c2960-lanbasek9-mz.150-2.SE/c2960-lanbasek9-mz.150-2.SE.bin