Cisco Router Environment
Dear viewers,
Today we are discuss some important cisco
router mode and some router elements. This information is very
important our professional sector because when we are properly maintain
the cisco router. So, build our knowledge……….
Router>
EXEC (user) mode; LOWEST level of access.
This allows router examination of router status, examination of router
configurable components, see routing tables, and do non-destructive
troubleshooting. However, you cannot change the configuration, view the
configuration files, or control the router in any way.
Router#
Privileged (enable) EXEC mode; FULL
router access. This mode allows you to have all the privileges of EXEC
(user) mode plus commands that enable you to change the configuration,
perform testing that could potentially disrupt traffic, reboot, and view
configuration files.
From here you may enter Global
Configuration Mode (command: ‘CONFIGURE TERMINAL’ to enter and ‘EXIT’ or
‘CTRL-Z’ to exit). The prompt will become Router (config)#. This allows
you to perform tasks that affect the entire router, such as naming the
router, configuration of banner messages, enabling routed protocols, and
generally anything that affects the operation of the entire router.
Setup mode is different from configuration mode in that setup mode
appears when there is no configuration file present. Upon entering setup
mode, Cisco IOS will ask for basic configuration parameters.
Router Elements:
RAM (Random Access Memory);
stores the running configuration, routing tables, and packet buffers.
Some routers, such as the 2500 series, run IOS from Flash, not RAM.
Flash Memory; stores the compressed OS (IOS) image. Flash memory is either EEPROM or PCMCIA card.
NVRAM (Non-Volatile Ram);
memory that does not lose information when power is lost. Stores the
system’s startup configuration file and the configuration register.
NVRAM uses a battery to maintain the data when power is off.
ROM (Read Only Memory);
Memory containing micro-code for basic functions to start and maintain
the router. ROM is not typically used after the IOS is loaded. RXBOOT is
located here.
Configuration Register; a
16 bit register used to contrl how the router boots up, where the IOS
image is, how to deal with the NVRAM configuration, setting the console
baud rate, and enabling or disabling the break function. Changing bit 6
from 0 to 1 will bypass the NVRAM settings and allow access to the
router in the event a password is lost.
The lowest four bits in the configuration
register control the startup sequence. If a router does not find a
valid configuration file when booting, it will enter a setup dialog with
the prompt “Would you like to enter the initial configuration dialog?”
This will allow you to set your router with minimal configuration
(hostname, passwords, protocols, etc). When finished, the router writes
the configuration to NVRAM and RAM.
Interfaces; the physical
connections to the external world. These often include Ethernet
connections. ATM, Token Ring, FDDI, Console, and auxiliary ports. For
the console interface, a communications package (such as HyperTerminal)
may be used. A console cable will be needed (DB-9 serial to RJ-45). Set
the COM port settings to 9600bps, 8 data bits, NO parity, 1 stop bit,
and NO flow control.
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