ROUTER COMPONENT(including procedure to configuration the router)

ROUTER:

A router is a device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP's network. Routers are located at gateways, the places where two or more networks connect.

Routers use headers and forwarding tables to determine the best path for forwarding the packets, and they use protocols such as ICMP to communicate with each other and configure the best route between any two hosts.

ROUTER IMAGES:

LINKSYS ROUTER FRONT VIEW

BACK VIEW

BASIC CONNECTION ARE CONNECTED WITH ROUTER:

:

Cisco Router Components:

• Bootstrap

                     – Brings up the router during initialization

• POST

                     – Checks basic functionality; hardware & interfaces

• ROM monitor

                     – Manufacturing testing & troubleshooting

• Mini-IOS

                     – Loads Cisco IOS into flash memory

• RAM

                     – Holds packet buffers, routing tables, & s/w

                     – Stores running-config

• ROM

                     – Starts & maintains the router

• Flash Memory

                     – Holds Cisco IOS

         – Not erased when the router is reloaded

• NVRAM

                    – Holds router (& switch) configurations

                    – Not erased when the router is reloaded

• Configuration Register

                    – Controls how the router boots up

BOOTING SEQUENCE:

 • Router performs a POST

• Bootstrap looks for & loads the Cisco IOS

• IOS software looks for a valid configuration file

• Startup-config file (from NVRAM) is loaded

                      – If startup-config file is not found, the router will start the setup mode

Configuration Registers

• Register

– 16-bit software written into NVRAM

– Loads from flash memory & looks for the startup-config file

• Configuration Register Bits

– 16 bits read 15-0, from left to right

– default setting: 0x2102

Register 2 1 0 2___

Bit number 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Binary 0 0 1 0 0 0 0 1 0 0 0 0 0 0 1 0

NOTE: 0x means the digits that follow are in hexadecimal

Checking the Register Value

Router#sh version

Cisco Internetwork Operating System Software

IOS ™ C2600 Software (C2600-I-M), Version 12.0(3)T3

RELEASE SOFTWARE (fc1)

[output cut]

Configuration register is 0x2102

Changing the Configuration Register

• Force the system into the ROM monitor mode

• Select a boot source & default boot filename

• Enable or disable the Brreak function

• Set the console terminal baud rate

• Load operating software from ROM

• Enable booting from a TFTP server

Router(config)#config-register 0x0101

Router(config)#^Z

Router#sh ver

Configuration register is 0x2102 (will be 0x0101 at next reload)

Recovering Passwords:

1: Boot the router & interrupt the boot sequence by performing a break

2: Change the configuration register to turn on bit 6 (0x2142)

3: Reload the router

4: Enter the privileged mode

5: Copy the startup-config to running-config

6: Change the password

7: Reset the configuration register to the default value

8: Reload the router

STEP BY STEP PROCEDURE:

1. Boot the router & interrupt the boot sequence by performing a

break using the Ctrl+Break key combination.

You may need to upgrade your version of hyper-terminal in

order for this to work successfully.

2. Change the configuration register to turn on bit 6 (0x2142)

rommon>confreg 0x2142

You must reset or power cycle for new config to take effect

3. Reload the router

– Type reset

• The router will reload & ask if you want to enter setup mode

– Answer NO

4. Enter the privileged mode

– Router>enable

– Router#

5. Copy the startup-config to running-config

Router#copy startup-config running-config

Change the password

Router#config t

Router(config)#enable secret ciisco

7. Reset the configuration register to the default value

Router(config)#config-register 0x2102

8. Reload the router