Composition of a CISCO router
A Cisco router is composed of internal and external components
mean interior components not visible from the outside:
- RAM
- NVRAM
- FLASH
- ROM
The external components are:
5. Interfaces
6. AUXILIARY
7. CONSOLE
1) RAM / DRAM
And 'the memory used in normal operation for routing tables, ARP-cache the content of this memory is cleared off with a
2) NVRAM
The startup configuration is stored here and is not lost when a shutdown or reboot the router.
3) FLASH
Contains the IOS (Internetworking Operating System) and other useful files is the permanent memory of the hard disk in a PC.
4) ROM
Memory containing the diagnostic software and to boot (just need to boot). to update replace the internal chip.
5) AUXILIARY
Asynchronous port for remote configuration and / or connecting additional peripherals.
6) CONSOLE
Also asynchronous port used for connecting the router to the PC serial port.
7) INTERFACES
Interfaces on the motherboard add-on modules (NM, WIC, VIC) used to interconnect the routers.
STARTUP OF A ROUTER
The startup phase of a Cisco router can be summarized as:
- Hardware Monitoring
- Research and load the IOS image
- Research and load configuration
The Boot ROM performs unadignostica base that, if successful, allow it to load IOS vienen normally sought in FLASH, man is the only place online where you can load the IOS.
The default search order is: FLASH, TFTP server, ROM.
The command "# Router (config) boot system" is the command to vary the exact location from which to draw the image to load IOS.
Once loaded the IOS identifies the hardware tested by the operation of the boot and conducts an visulizzazione console.
At this point it loads the configuration file in NVRAM. If not found to be a valid installation, operating system starts a process of interactive questions and answers based configuration (Setup dialog).
IF everything is ok with the following commands will see the configuration in RAM:
Router # show running-config
Router # write term
So THAT ain NVRAM:
Router # show startup-config
if we wanted to delete the configuration in NVRAM the command is:
Router # erase startup-config
or
Router # write erase
you can restart the router with the command:
Router # reload
Ilsetup interactive command is invoked by typing
Router # setup
In the configuration of a Cisco router commands entered from time to time, are stored in RAM.
The router makes them immediately operational but their effect would be exhausted in case of shutdown of the equipment.
To make the configuration effective, even after a subsequent reboot, you must save it in NVRAM, where it will be loaded to restart the router.
Router # write memory
abbreviabile in
Router # wr mem
Tags: CISCO , ROUTER
